Dissertations / Theses: 'Multibody Dynamics Simulation'

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Yamashita, Hiroki. "Flexible multibody dynamics approach for tire dynamics simulation." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2297.

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The objective of this study is to develop a high-fidelity physics-based flexible tire model that can be fully integrated into multibody dynamics computer algorithms for use in on-road and off-road vehicle dynamics simulation without ad-hoc co-simulation techniques. Despite the fact detailed finite element tire models using explicit finite element software have been widely utilized for structural design of tires by tire manufactures, it is recognized in the tire industry that existing state-of-the-art explicit finite element tire models are not capable of predicting the transient tire force characteristics accurately under severe vehicle maneuvering conditions due to the numerical instability that is essentially inevitable for explicit finite element procedures for severe loading scenarios and the lack of transient (dynamic) tire friction model suited for FE tire models. Furthermore, to integrate the deformable tire models into multibody full vehicle simulation, co-simulation technique could be an option for commercial software. However, there exist various challenges in co-simulation for the transient vehicle maneuvering simulation in terms of numerical stability and computational efficiency. The transient tire dynamics involves rapid changes in contact forces due to the abrupt braking and steering input, thus use of co-simulation requires very small step size to ensure the numerical stability and energy balance between two separate simulation using different solvers. In order to address these essential and challenging issues on the high-fidelity flexible tire model suited for multibody vehicle dynamics simulation, a physics-based tire model using the flexible multibody dynamics approach is proposed in this study. To this end, a continuum mechanics based shear deformable laminated composite shell element is developed based on the finite element absolute nodal coordinate formulation for modeling the complex fiber reinforced rubber tire structure. The assumed natural strain (ANS) and enhanced assumed strain (EAS) approaches are introduced for alleviating element lockings exhibited in the element. Use of the concept of the absolute nodal coordinate formulation leads to various advantages for tire dynamics simulation in that (1) constant mass matrix can be obtained for fully nonlinear dynamics simulation; (2) exact modeling of rigid body motion is ensured when strains are zero; and (3) non-incremental solution procedure utilized in the general multibody dynamics computer algorithm can be directly applied without specialized updating schemes for finite rotations. Using the proposed shear deformable laminated composite shell element, a physics-based flexible tire model is developed. To account for the transient tire friction characteristics including the friction-induced hysteresis that appears in severe maneuvering conditions, the distributed parameter LuGre tire friction model is integrated into the flexible tire model. To this end, the contact patch predicted by the structural tire model is discretized into small strips across the tire width, and then each strip is further discretized into small elements to convert the partial differential equations of the LuGre tire friction model to the set of first-order ordinary differential equations. By doing so, the structural deformation of the flexible tire model and the LuGre tire friction force model are dynamically coupled in the final form of the equations, and these equations are integrated simultaneously forward in time at every time step. Furthermore, a systematic and automated procedure for parameter identification of LuGre tire friction model is developed. Since several fitting parameters are introduced to account for the nonlinear friction characteristics, the correlation of the model parameters with physical quantities are not clear, making the parameter identification of the LuGre tire friction model difficult. In the procedure developed in this study, friction parameters in terms of slip-dependent friction characteristics and adhesion parameter are estimated separately, and then all the parameters are identified using the nonlinear least squares fitting. Furthermore, the modified friction characteristic curve function is proposed for wet road conditions, in which the linear decay in friction is exhibited in the large slip velocity range. It is shown that use of the proposed numerical procedure leads to an accurate prediction of the LuGre model parameters for measured tire force characteristics under various loading and speed conditions. Furthermore, the fundamental tire properties including the load-deflection curve, the contact patch lengths, contact pressure distributions, and natural frequencies are validated against the test data. Several numerical examples for hard braking and cornering simulation are presented to demonstrate capabilities of the physics-based flexible tire model developed in this study. Finally, the physics-based flexible tire model is further extended for application to off-road mobility simulation. To this end, a locking-free 9-node brick element with the curvature coordinates at the center node is developed and justified for use in modeling a continuum soil with the capped Drucker-Prager failure criterion. Multiplicative finite strain plasticity theory is utilized to consider the large soil deformation exhibited in the tire/soil interaction simulation. In order to identify soil parameters including cohesion and friction angle, the triaxial soil test is conducted. Using the soil parameters identified including the plastic hardening parameters by the compression soil test, the continuum soil model developed is validated against the test data. Use of the high-fidelity physics-based tire/soil simulation model in off-road mobility simulation, however, leads to a very large computational model to consider a wide area of terrains. Thus, the computational cost dramatically increases as the size of the soil model increases. To address this issue, the component soil model is proposed such that soil elements far behind the tire can be removed from the equations of motion sequentially, and then new soil elements are added to the portion that the tire is heading to. That is, the soil behavior only in the vicinity of the rolling tire is solved in order to reduce the overall model dimensionality associated with the finite element soil model. It is shown that use of the component soil model leads to a significant reduction in computational time while ensuring the accuracy, making the use of the physics-based deformable tire/soil simulation capability feasible in off-road mobility simulation.

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Wong, Darrell. "Parallel implementation of multibody dynamics for real-time simulation." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/32391.

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A multibody dynamics formulation has been developed for the purposes of real-time simulation of large scale robotic mechanisms such as excavators. The formulation models the rigid body dynamics of any arbitrary tree structured mechanism, although at present the formulation is restricted to single degree of freedom rotational joints. This formulation is an example of the orthogonal complement approach, which describes the dynamics by projecting an initial description of the primitive equations of motion (the derivatives of translational and angular momentum plus the kinematic equations) from angular and translational Cartesian coordinates to relative angles. In this thesis the approach was developed from Newtonian and Eulerian principles. Novel single cpu algorithms for inertia matrix and force vector formation have been implemented. Novel multiprocessor algorithms were implemented for the inertia matrix and the force vector on a 2d [formula omitted] triangular mesh architecture. A feedforward systolic matrix solution technique was also implemented. These algorithms are of O(n) complexity, and together they form a parallel formulation which is more efficient than other parallel formulations in the literature for mechanisms with fewer than 15 degrees of freedom. A Caterpillar 215B excavator was simulated in real-time using an array of transputers, and teleoperation experiments were conducted to verify the formulation. Single cpu simulations of the PUMA 600 and a human torso were also conducted. Applied Science, Faculty of Electrical and Computer Engineering, Department of Graduate

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Choi, Jou-Young. "Flexible multibody analysis of thin structures with actuated components." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12532.

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Rodriguez, Jesus. "Modeling of complex systems using nonlinear, flexible multibody dynamics." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12344.

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Sumer, Yalcin Faik. "Predictive Control of Multibody Systems for the Simulation of Maneuvering Rotorcraft." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6940.

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Simulation of maneuvers with multibody models of rotorcraft vehicles is an important research area due to its complexity. During the maneuvering flight, some important design limitations are encountered such as maximum loads and maximum turning rates near the proximity of the flight envelope. This increases the demand on high fidelity models in order to define appropriate controls to steer the model close to the desired trajectory while staying inside the boundaries. A framework based on the hierarchical decomposition of the problem is used for this study. The system should be capable of generating the track by itself based on the given criteria and also capable of piloting the model of the vehicle along this track. The generated track must be compatible with the dynamic characteristics of the vehicle. Defining the constraints for the maneuver is of crucial importance when the vehicle is operating close to its performance boundaries. In order to make the problem computationally feasible, two models of the same vehicle are used where the reduced model captures the coarse level flight dynamics, while the fine scale comprehensive model represents the plant. The problem is defined by introducing planning layer and control layer strategies. The planning layer stands for solving the optimal control problem for a specific maneuver of a reduced vehicle model. The control layer takes the resulting optimal trajectory as an optimal reference path, then tracks it by using a non-linear model predictive formulation and accordingly steers the multibody model. Reduced models for the planning and tracking layers are adapted by using neural network approach online to optimize the predictive capabilities of planner and tracker. Optimal neural network architecture is obtained to augment the reduced model in the best way. The methodology of adaptive learning rate is experimented with different strategies. Some useful training modes and algorithms are proposed for these type of applications. It is observed that the neural network increased the predictive capabilities of the reduced model in a robust way. The proposed framework is demonstrated on a maneuvering problem by studying an obstacle avoidance example with violent pull-up and pull-down.

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Ricci, Stefano <1982&gt. "Model reduction techniques in flexible multibody dynamics with application to engine cranktrain simulation." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5882/.

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The development of a multibody model of a motorbike engine cranktrain is presented in this work, with an emphasis on flexible component model reduction. A modelling methodology based upon the adoption of non-ideal joints at interface locations, and the inclusion of component flexibility, is developed: both are necessary tasks if one wants to capture dynamic effects which arise in lightweight, high-speed applications. With regard to the first topic, both a ball bearing model and a journal bearing model are implemented, in order to properly capture the dynamic effects of the main connections in the system: angular contact ball bearings are modelled according to a five-DOF nonlinear scheme in order to grasp the crankshaft main bearings behaviour, while an impedance-based hydrodynamic bearing model is implemented providing an enhanced operation prediction at the conrod big end locations. Concerning the second matter, flexible models of the crankshaft and the connecting rod are produced. The well-established Craig-Bampton reduction technique is adopted as a general framework to obtain reduced model representations which are suitable for the subsequent multibody analyses. A particular component mode selection procedure is implemented, based on the concept of Effective Interface Mass, allowing an assessment of the accuracy of the reduced models prior to the nonlinear simulation phase. In addition, a procedure to alleviate the effects of modal truncation, based on the Modal Truncation Augmentation approach, is developed. In order to assess the performances of the proposed modal reduction schemes, numerical tests are performed onto the crankshaft and the conrod models in both frequency and modal domains. A multibody model of the cranktrain is eventually assembled and simulated using a commercial software. Numerical results are presented, demonstrating the effectiveness of the implemented flexible model reduction techniques. The advantages over the conventional frequency-based truncation approach are discussed.

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Komodromos, Petros I. (Petros Ioannis). "Development and implementation of a combined discrete and finite element multibody dynamics simulation environment." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/31102.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001. Includes bibliographical references (p. [195]-198) and index. Some engineering applications and physical phenomena involve multiple bodies that undergo large displacements involving collisions between the bodies. Considering the difficulties and cost associated when conducting physical experiments of such systems, there is a demand for numerical simulation capabilities. The discrete element methods (DEM) are numerical techniques that have been specifically developed to facilitate simulations of distinct bodies that interact with each other through contact forces. In DEM the simulated bodies are typically assumed to be infinitely rigid. However, there are multibody systems for which it is useful to take into account the deformability of the simulated bodies. The objective of this research is to incorporate deformability in DEM, enabling the evaluation of the stress and strain distributions within simulated bodies during simulation. In order to achieve this goal, an Updated Lagrangian (UL) Finite Element (FE) formulation and an explicit time integration scheme have been employed together with some simplifiying assumptions to linearize this highly nonlinear contact problem and obtain solutions with realistic computational cost. An object-oriented extendable computational tool has been built specifically to allow us to simulate multiple distinct bodies that interact through contact forces allowing selected bodies to be deformable. Database technology has also been utilized in order to efficiently handle the huge amounts of computed results. by Petros Komodromos. Ph.D.

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Aghaei, Shayan. "Acoustic Radiation Of An Automotive Component Using Multi-Body Dynamics." Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288710.

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An important facet of creating high-quality vehicles is to create components that are quiet and smooth under operation. In reality, however, it is challenging to measure the sound that some automotive components make under load because it requires specialist facilities and equipment which are expensive to acquire. Furthermore, the motors used in testbeds drown out the noise emitted from much quieter components, such as a Power Transfer Unit (PTU). This thesis aims to solve these issues by outlining the steps required to virtually estimate the acoustic radiation of a PTU using the Transmission Error (TE) as the input excitation via multi-body dynamics (MBD). MBD is used to estimate the housing vibrations, which can then be coupled with an acoustic tool to create a radiation analysis. Thus, creating a viable method to measure the acoustic performance without incurring significant expenses. Furthermore, it enables noise and vibration analyses to be incorporated more easily into the design stage. This thesis analysed the sound radiated due to gear whine which arises due to the TE and occurs at the gear mesh frequency and its multiples. The simulations highlighted that the TE can be accurately predicted using the methods outlined in this thesis. Similarly, the method can reliably obtain the vibrations of the housing. The results from this analysis show that at 2000 rpm the PTU was sensitive to vibrations at 500, 1000 and 1500 Hz, the largest amplitude being at 1000 Hz. Furthermore, the Sound Power Level (SWL) was proportional to the vibration amplitudes in the system. Analytical calculations were conducted to verify the methods and showed a strong correlation. However, it was concluded that experiments are required to further verify the findings in this thesis. En viktig aspekt i att skapa fordon av hög kvalitet är att skapa komponenter som är tysta och smidiga under drift. I verkligheten är det dock svårt att mäta ljudet som vissa fordonskompo- nenter ger under belastning eftersom det kräver specialanläggningar och utrustning, vilket är dyrt att skaffa. Dessutom maskerar motorerna som används i testbäddar ut bullret från mycket tystare komponenter, till exempel en kraftöverföringsenhet (PTU). Detta examensar- bete syftar till att lösa dessa problem genom att beskriva de steg som krävs för att virtuellt uppskatta den akustiska strålningen av en PTU med hjälp av transmissionsfelet (TE) som ingångsexcitation via flerkroppsdynamik (multi-body dynamics, MBD). MBD används för att uppskatta kåpans vibrationer, som sedan kan kopplas till ett akustiskt verktyg för att skapa en ljudutstrålningsanalys. Således skapas en genomförbar metod för att mäta den akustiska pre- standan utan att medföra betydande kostnader. Dessutom möjliggör det att lättare integrera ljud- och vibrationsanalyser i designfasen. Detta examensarbete analyserade ljudet som utstrålats på grund av kugghjulsljud, som uppstår på grund av TE och uppträder vid kuggingreppsfrekvensen och dess multiplar. Simuleringarna belyste att TE kan förutsägas exakt med de metoder som beskrivs i detta examensarbete. På samma sätt kan metoden på ett tillförlitligt sätt uppnå kåpans vibrationer. Resultaten från denna analys visar att vid 2000 rpm var PTU känslig för vibrationer vid 500, 1000 och 1500 Hz, den största amplituden var vid 1000 Hz. Dessutom var ljudeffektsnivån (SWL) proportionell mot vibrationsamplituderna i systemet. Analytiska beräkningar genomfördes för att verifiera metoderna och visade en stark korrelation. Dock drogs slutsatsen att experiment krävs för att ytterligare verifiera resultaten i detta arbete.

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Oral, Gokhan. "Flexible Multibody Dynamic Modeling And Simulation Of Rhex Hexapod Robot With Half Circular Compliant Legs." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610137/index.pdf.

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The focus of interest in this study is the RHex robot, which is a hexapod robot that is capable of locomotion over rugged, fractured terrain through statically and dynamically stable gaits while stability of locomotion is preserved. RHex is primarily a research platform that is based on over five years of previous research. The purpose of the study is to build a virtual prototype of RHex robot in order to simulate different behavior without manufacturing expensive prototypes. The virtual prototype is modeled in MSC ADAMS software which is a very useful program to simulate flexible multibody dynamical systems. The flexible half circular legs are modeled in a finite element program (MSC NASTRAN) and are embedded in the main model. Finally a closed loop control mechanism is built in MATLAB to be able to simulate real autonomous RHex robot. The interaction of MATLAB and MSC ADAMS softwares is studied.

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Schmitt, Alexander Georg [Verfasser], and Robert [Akademischer Betreuer] Seifried. "Real-time simulation of flexible multibody systems in vehicle dynamics / Alexander Georg Schmitt ; Betreuer: Robert Seifried." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2019. http://d-nb.info/1200058712/34.

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Lurgo, Alessandromaria [Verfasser]. "Multibody-CFD Co-Simulation of the Dynamics of the High-Lift System of Transport Aircraft / Alessandromaria Lurgo." München : Verlag Dr. Hut, 2019. http://d-nb.info/1200755200/34.

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Nelkov, Nyagolov Dimitar, Bashir Abbas, and Genovski Filip Valentinov. "Simulation of the Geometry Influence on Curvic Coupled Engagement." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-27291.

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The thesis is performed in order to improve the curvic coupled engagement of a dog clutch situated in the transfer case of a truck. The dog clutch is used to engage the so called all-wheel-drive system of the truck. If the driver tries to engage the all-wheel-drive when truck’s rear wheels already skid, due to a slippery surface a relative rotational speed in the dog clutch will occur. This relative rotational speed will cause the dog clutch to bounce back of itself before engagement, or to not engage at all. The dog clutch has been redesigned to prevent this. Dynamic simulations using MD Adams have been made for the existing model, for the models created in previous works, and for the new model in order to figure out which of them will show the most stable engagement, at high relative rotational speed. The implemented simulations show that better results can be obtained. Separation into two parts of the disc pushed by the fork, shows that dog clutch’s engagement is faster and more stable, comparing to the original model and the other created models. The new model shows better coupling in the whole range of the relative rotational speed from 50 up to 120rpm.

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Mehdi, Pour Reza. "Transmission Dynamics Modelling : Gear Whine Simulation Using AVL Excite." Thesis, KTH, Fordonsdesign, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234817.

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Nowadays, increasing pressure from legislation and customer demands in the automotive industryare forcing manufacturers to produce greener vehicles with lower emissions and fuel consumption.As a result, electrified and hybrid vehicles are a growing popular alternative to traditional internalcombustion engines (ICE). The noise from an electric vehicle comes mainly from contact betweentyres and road, wind resistance and driveline. The noise emitted from the driveline is for the mostpart related to the gearbox. When developing a driveline, it is a factor of importance to estimatethe noise radiating from the gearbox to achieve an acceptable design.Gears are used extensively in the driveline of electric vehicles. As the gears are in mesh, a mainintrusive concern is known as gear whine noise. Gear whine noise is an undesired vibroacousticphenomenon and is likely to originate through the gear contacts and be transferred through themechanical components to the housing where the vibrations are converted into airborne andstructure-borne noise. The gear whine noise originates primarily from the excitation coming fromtransmission error (TE). Transmission error is defined as the difference between the ideal smoothtransfer of motion of a gear and what is in practice due to lack of smoothness.The main objective of this study is to simulate the vibrations generated by the gear whine noise inan electric powertrain line developed by AVL Vicura. The electric transmission used in this studyprovides only a fixed overall gear ratio, i.e. 9.59, under all operation conditions. It is assumed thatthe system is excited only by the transmission error and the mesh stiffness of the gear contacts. Inorder to perform NVH analysis under different operating conditions, a multibody dynamics modelaccording to the AVL Excite program has been developed. The dynamic simulations are thencompared with previous experimental measurements provided by AVL Vicura.Two validation criteria have been used to analyse the dynamic behaviour of the AVL Excite model:signal processing using the FFT method and comparison with the experimental measurements.The results from the AVL Excite model show that the FFT criterion is quite successful and allexcitation frequencies are properly observed in FFT plots. Nevertheless, when it comes to thesecond criterion, as long as not all dynamic parameters of the system such as damping or stiffnesscoefficients are provided with certainty in the model, it is too difficult to investigate the accuracy ofthe AVL Excite model.Another investigation is a numerical design study to analyses how the damping coefficientsinfluence the response. After reducing the damping parameters, the results show that the housingand bearings have the highest influence on the response. If more acceptable results are desired,future studies must be concentrated on these to obtain more acceptable damping values. För närvarande tvingar ökat tryck från lagstiftning och kundkrav inom bilindustrin tillverkarna attproducera grönare fordon med lägre utsläpp och bränsleförbrukning. Som ett resultat ärelektrifierade och hybridfordon ett växande populärt alternativ till traditionellaförbränningsmotorer (ICE). Bullret från ett elfordon kommer främst från kontakten mellan däckoch väg, vindmotstånd och drivlinan. Bullret från drivlinan är i huvudsak relaterat till växellådan.Vid utveckling av en drivlina är det av betydelse att uppskatta bullret från växellådan för att uppnåen acceptabel design.Utväxlingar används i stor utsträckning i elfordons drivlina. Eftersom kugghjulen är i kontaktuppstår ett huvudproblem som är känt som ett vinande ljud från kugghjulskontakten.Kugghjulsljud är ett oönskat vibro-akustiskt fenomen och uppstår sannolikt på grund avkugghjulkontakterna och överförs via de mekaniska komponenterna till växellådshuset därvibrationerna omvandlas till luftburet och strukturburet ljud. Kugghjulsljudet härstammarhuvudsakligen från exciteringen som kommer från transmissionsfel (TE) i kugghjulskontakten.Överföringsfelet definieras som skillnaden mellan den ideala smidiga rörelseöverföringen hoskugghjulen och rörelsen som sker i verkligheten på grund av ojämnheter.Huvudsyftet med denna studie är att simulera vibrationerna som genereras avkugghjulskontakterna i en elektrisk drivlina utvecklad av AVL Vicura. Den elektriska drivlinan somanvänds i denna studie har endast ett fast utväxlingsförhållande, dvs 9,59, för alladriftsförhållanden. Det antas att systemet är exciterat endast av överföringsfelet och kugghjulensstyvhet i kuggkontakterna. För att kunna utföra NVH-analys under olika driftsförhållanden har enstelkroppsdynamikmodell utvecklats med hjälp av programmet AVL Excite. De dynamiskasimuleringarna jämförs sedan med tidigare experimentella mätningar som tillhandahålls av AVLVicura.Två valideringskriterier har använts för att analysera det dynamiska beteendet hos AVL Excitemodellen:signalbehandling med FFT-metoden och jämförelse med experimentella mätningar.Resultaten från AVL Excite-modellen visar att FFT-kriteriet är ganska framgångsrikt och allaexcitationsfrekvenser observeras korrekt i FFT-diagrammen. Men när det gäller det andra kriteriet,så länge som inte alla dynamiska parametrar i systemet, såsom dämpnings- ellerstyvhetskoefficienter, är tillförlitliga i modellen, är det för svårt att undersöka exaktheten hos AVLExcite-modellen.En annan undersökning som utförts är en numerisk designstudie för att analysera hurdämpningskoefficienterna påverkar responsen. Efter minskning av dämpningsparametrarna visarresultaten att växellådshus och lager har störst inflytande på resultatet. Om mer acceptabla resultatär önskvärda måste framtida studier koncentreras på dessa parametrar för att uppnå mer acceptabladämpningsvärden.

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Wang, Da. "Accelerated granular matter simulation." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-110164.

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Modeling and simulation of granular matter has important applications in both natural science and industry. One widely used method is the discrete element method (DEM). It can be used for simulating granular matter in the gaseous, liquid as well as solid regime whereas alternative methods are in general applicable to only one. Discrete element analysis of large systems is, however, limited by long computational time. A number of solutions to radically improve the computational efficiency of DEM simulations are developed and analysed. These include treating the material as a nonsmooth dynamical system and methods for reducing the computational effort for solving the complementarity problem that arise from implicit treatment of the contact laws. This allow for large time-step integration and ultimately more and faster simulation studies or analysis of more complex systems. Acceleration methods that can reduce the computational complexity and degrees of freedom have been invented. These solutions are investigated in numerical experiments, validated using experimental data and applied for design exploration of iron ore pelletising systems. This work has been generously supported by Algoryx Simulation, LKAB (dnr 223-2442-09), Umeå University and VINNOVA (2014-01901).

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Telecký, Vojtěch. "Vliv aerodynamických sil na jízdní komfort vozidla a polohu karoserie." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254388.

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Wuillaume, Pierre-Yves. "Simulation numérique des opérations d’installation pour les fermes d’éoliennes offshore." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0003/document.

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L’éolien offshore est l’énergie marine la plus avancée et utilisée dans le monde. Afin d’accroître l’énergie extraite du vent, les dimensions des éoliennes deviennent plus importantes et les parcs éoliens sont installées de plus en plus loin des côtes, où les mers sont plus agitées et les vents plus forts. De fait, les opérations marines sont plus complexes et plus chères et les fenêtres météo sont écourtées et se raréfient. Dans le cadre de cette thèse, un logiciel de simulation numérique des opérations marines est développé, en particulier pour des applications de descentes et de remontées de colis lourds. L’Algorithme aux Corps Rigides Composites, implémenté dans le logiciel InWave, est utilisé pour modéliser le système multicorps. Un modèle de câble et de treuil est développé, suivant la théorie multicorps utilisée, et comparé à la théorie câble classique dite « lumped mass ». Les efforts hydrodynamiques ainsi que les interactions hydrodynamiques sont modélisés par une théorie potentiel instationnaire satisfaisant l’hypothèse de faible perturbation, dite « weak-scatterer ». L’approche « weak-scatterer » du logiciel WS_CN est étendue aux simulations multi-flotteurs et validée par comparaison avec des données expérimentales. InWave et WS_CN sont couplés afin de résoudre l’interaction houle-structure pour des systèmes multicorps articulés en mer. Un couplage fort est adopté pour sa robustesse. L’équation de couplage est établie et validée via des comparaisons avec WS_CN. Le logiciel ainsi crée se nomme InWaveS_CN et utilise un code d’intégration en Python. Une nouvelle stratégie de maillage, basée sur un algorithme de découpe de maillages et une méthode par avance de front, est développée dans WS_CN. Enfin, des essais en bassin d’une opération de redressement ont été menés à l’ECN. La comparaison entre les simulations numériques et les données expérimentales offre une première et prometteuse validation d’InWaveS_CN Offshore wind represents the most advanced and used marine energy in the world. To increase the wind power extraction, turbines grow in size and wind farms are installed further offshore in presence of rough seas and strong winds. Marine operations become more challenging and expensive, weather windows are shorter and less frequent. This PhD work focuses on the development of a numerical tool to simulate marine operations with consistency, in particular lowering and lifting operations. The Composite-Rigid-Body Algorithm, implemented in the numerical tool InWave, is used to model multibody systems. A cable model and a winch model are developed following this multibody approach and compared to the classical low-order lumped mass theory. Hydrodynamic loads and hydrodynamic interactions are simulated using an unsteady potential flow theory based on the weakscatterer hypothesis, implemented in the numerical tool WS_CN. This approach is extended to multibody simulations and validated with comparisons to experimental data. InWave and WS_CN are coupled to solve wavestructure interaction for articulated multibody systems with large relative motions in waves. A tight coupling is selected for its robustness. The coupling equation is derived and validated from comparisons with WS_CN. This leads to the creation of a new numerical tool, InWaveS_CN, using Python as glue code language. A new mesh strategy, based on the coupling between a panel cutting method and an advance front method, is developed in WS_CN. Experiments of an upending operation were conducted at Ecole Centrale de Nantes. The comparison between the numerical simulations and the experimental data leads to a first and promising validation of InWaveS_CN

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Nakhimovski, Iakov. "Contributions to the Modeling and Simulation of Mechanical Systems with Detailed Contact Analyses." Doctoral thesis, Linköpings universitet, PELAB - Laboratoriet för programmeringsomgivningar, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6342.

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The motivation for this thesis was the need for further development of multibody dynamics simulation packages focused on detailed contact analysis. The thesis makes contributions in three different areas: Part I summarizes the equations, algorithms and design decisions necessary for dynamics simulation of flexible bodies with moving contacts. The assumed general shape function approach is presented. Additionally, the described technique enables studies of the residual stress release during grinding of flexible bodies. The proposed set of mode shapes was also successfully applied for modeling of heat flow. Part II is motivated by the need to reduce the computation time. The availability of the new cost-efficient multiprocessor computers triggered the development of the presented hybrid parallelization framework. The framework is designed to be easily portable and can be implemented without any system level coding or compiler modifications. Part III is motivated by the need for inter-operation with other simulation tools. A co-simulation framework based on the Transmission Line Modeling (TLM) technology was developed. The framework enables integration of several different simulation components into a single time-domain simulation. The framework has been used for connecting MSC.ADAMS and SKF BEAST simulation models. Throughout the thesis the approach was to present a practitioner roadmap. The detailed description of the theoretical results relevant for a real software implementation is put in focus. The software design decisions are discussed and the results of real industrial simulations are presented. This work has been supported by SKF, SSF/ProViking, ECSEL, KK-stiftelsen.

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Gollee, Christian, and Clemens Troll. "Mehrkörpersimulation eines ebenen Koppelgetriebes mittels Matlab / ADAMS -Co-Simulation." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-225922.

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Mit Hilfe der Matlab/ADAMS-Co-Simulation wird ein ebenes Koppelgetriebe (5- Gelenk) untersucht und anschließend die Wirkpaarung mit einem Stückgut betrachtet. Dabei werden verschiedene Modellierungsstufen angewendet und die Simulationsergebnisse Messergebnissen vom Versuchsstand gegenübergestellt. Daneben wird die grundlegende Herangehensweise beim Einsatz dieser Simulationswerkzeuge erläutert.

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Viganico, Carlos Eduardo Henke. "Avaliação dinâmica de veículos ferroviários através de um sistema multicorpos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/27936.

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Os acidentes com veículos ferroviários podem ter origem em muitos fatores, mas os principais são relacionados com a dinâmica do veículo e carga, via permanente em péssimas condições e operações inseguras nos trens. Os acidentes causam mortes, danos materiais e ao meio ambiente e prejuízos para as operadoras e seus clientes. Para avaliar a dinâmica dos veículos ferroviários, um sistema multicorpos foi desenvolvido (programa computacional) para representar matematicamente um típico veículo ferroviário com seus principais graus de liberdade. As equações de movimento foram desenvolvidas utilizando a equação de Lagrange de movimento, a qual considera princípios da mecânica como: energia cinética, energia potencial e a dissipação de energia do sistema. As equações acopladas e desacopladas são programadas e resolvidas para acelerações, estas são integradas duas vezes, obtendo-se as velocidades e deslocamentos. A partir das repostas do sistema o comportamento do veículo pode ser avaliado em várias condições de operação. A verificação do programa é realizada através de comparações com resultados de outros programas publicados na literatura, onde se verifica uma adequada correlação. Avaliações nos principais regimes de operação são realizadas de forma a simular condições determinadas pela norma AAR e condições extras originadas por irregularidades aperiódicas da via do tipo cusp e jog. Dois tipos de veículos são simulados para representar as condições típicas das ferrovias brasileiras: veículos operando em bitola métrica e em bitola larga. Os resultados das simulações apresentam valores de amplitude e fase que estão de acordo com resultados expostos nas normas e na literatura ferroviária de referência utilizada neste trabalho. A avaliação dinâmica de veículos ferroviários através de um programa computacional é importante, pois considera as principais características dos veículos e via permanente. A possibilidade de representar o veículo com uma configuração simples em relação a programas comerciais permite uma simulação rápida e confiável para determinar respostas em regimes como: hunting, twist e roll, pitch e bounce e yaw e sway. The accidents with rail vehicles has origin due to many factors, but the main ones are related to the dynamics of the vehicle and load, the spoiled railway and unsafe operations on the trains. Accidents causing deaths, damage to property and the environment and damage to operators and their customers. In order to evaluate the railway vehicles dynamics, it was developed a multibody system (computer program) to mathematically represent a typical railway vehicle with its main degrees of freedom. The motion equations were developed using Lagrange's equation of motion, which takes into consideration the principles of mechanical, as: kinetic energy, potential energy and energy dissipation of the system. The coupled and uncoupled equations are programmed and solved for accelerations, which are twice integrated, in order to have the speeds and displacements. From the system’s responses, the vehicle behavior can be evaluated in several operating conditions. The comparison of the program is accomplished through confrontations with results from other programs in the literature, in which a good correlation is verified. The evaluations in the main regimes of operation are made in a way simulate the conditions determined by the standard conditions and extra conditions caused by aperiodic irregularities of the track. Two types of vehicles are simulated to represent the typical conditions of Brazilian railways: vehicles operating on meter gauge and large gauge. The simulation results show that amplitude and phase values are consistent with results presented in the standards and in the railway literature of reference of this work. The rail vehicles dynamic evaluation through a computer program was important because it considers the main characteristics of vehicles and permanent way. The possibility of representing the vehicle with a simple configuration in relation to commercial softwares allows a fast and reliable simulation to determine responses in regimes as: hunting, twist and roll, pitch and bounce and yaw and sway.

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Mehdi, Pour Reza. "Transmission DynamicsModelling : Gear Whine Simulation Using AVL Excite." Thesis, KTH, Fordonsdynamik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-243090.

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Nowadays, increasing pressure from legislation and customer demands in the automotive industry are forcing manufacturers to produce greener vehicles with lower emissions and fuel consumption.As a result, electrified and hybrid vehicles are a growing popular alternative to traditional internal combustion engines (ICE). The noise from an electric vehicle comes mainly from contact between tyres and road, wind resistance and driveline. The noise emitted from the driveline is for the mostpart related to the gearbox. When developing a driveline, it is a factor of importance to estimate the noise radiating from the gearbox to achieve an acceptable design.Gears are used extensively in the driveline of electric vehicles. As the gears are in mesh, a main intrusive concern is known as gear whine noise. Gear whine noise is an undesired vibroacoustic phenomenon and is likely to originate through the gear contacts and be transferred through themechanical components to the housing where the vibrations are converted into airborne and structure-borne noise. The gear whine noise originates primarily from the excitation coming from transmission error (TE). Transmission error is defined as the difference between the ideal smoothtransfer of motion of a gear and what is in practice due to lack of smoothness.The main objective of this study is to simulate the vibrations generated by the gear whine noise in an electric powertrain line developed by AVL Vicura. The electric transmission used in this study provides only a fixed overall gear ratio, i.e. 9.59, under all operation conditions. It is assumed thatthe system is excited only by the transmission error and the mesh stiffness of the gear contacts. In order to perform NVH analysis under different operating conditions, a multibody dynamics model according to the AVL Excite program has been developed. The dynamic simulations are thencompared with previous experimental measurements provided by AVL Vicura.Two validation criteria have been used to analyse the dynamic behaviour of the AVL Excite model: signal processing using the FFT method and comparison with the experimental measurements.The results from the AVL Excite model show that the FFT criterion is quite successful and all excitation frequencies are properly observed in FFT plots. Nevertheless, when it comes to the second criterion, as long as not all dynamic parameters of the system such as damping or stiffnesscoefficients are provided with certainty in the model, it is too difficult to investigate the accuracy of the AVL Excite model. Another investigation is a numerical design study to analyses how the damping coefficients influence the response. After reducing the damping parameters, the results show that the housing and bearings have the highest influence on the response. If more acceptable results are desired,future studies must be concentrated on these to obtain more acceptable damping values. För närvarande tvingar ökat tryck från lagstiftning och kundkrav inom bilindustrin tillverkarna attproducera grönare fordon med lägre utsläpp och bränsleförbrukning. Som ett resultat ärelektrifierade och hybridfordon ett växande populärt alternativ till traditionellaförbränningsmotorer (ICE). Bullret från ett elfordon kommer främst från kontakten mellan däckoch väg, vindmotstånd och drivlinan. Bullret från drivlinan är i huvudsak relaterat till växellådan.Vid utveckling av en drivlina är det av betydelse att uppskatta bullret från växellådan för att uppnåen acceptabel design.Utväxlingar används i stor utsträckning i elfordons drivlina. Eftersom kugghjulen är i kontaktuppstår ett huvudproblem som är känt som ett vinande ljud från kugghjulskontakten.Kugghjulsljud är ett oönskat vibro-akustiskt fenomen och uppstår sannolikt på grund avkugghjulkontakterna och överförs via de mekaniska komponenterna till växellådshuset därvibrationerna omvandlas till luftburet och strukturburet ljud. Kugghjulsljudet härstammarhuvudsakligen från exciteringen som kommer från transmissionsfel (TE) i kugghjulskontakten.Överföringsfelet definieras som skillnaden mellan den ideala smidiga rörelseöverföringen hoskugghjulen och rörelsen som sker i verkligheten på grund av ojämnheter.Huvudsyftet med denna studie är att simulera vibrationerna som genereras avkugghjulskontakterna i en elektrisk drivlina utvecklad av AVL Vicura. Den elektriska drivlinan somanvänds i denna studie har endast ett fast utväxlingsförhållande, dvs 9,59, för alladriftsförhållanden. Det antas att systemet är exciterat endast av överföringsfelet och kugghjulensstyvhet i kuggkontakterna. För att kunna utföra NVH-analys under olika driftsförhållanden har enstelkroppsdynamikmodell utvecklats med hjälp av programmet AVL Excite. De dynamiskasimuleringarna jämförs sedan med tidigare experimentella mätningar som tillhandahålls av AVLVicura.Två valideringskriterier har använts för att analysera det dynamiska beteendet hos AVL Excitemodellen:signalbehandling med FFT-metoden och jämförelse med experimentella mätningar.Resultaten från AVL Excite-modellen visar att FFT-kriteriet är ganska framgångsrikt och allaexcitationsfrekvenser observeras korrekt i FFT-diagrammen. Men när det gäller det andra kriteriet,så länge som inte alla dynamiska parametrar i systemet, såsom dämpnings- ellerstyvhetskoefficienter, är tillförlitliga i modellen, är det för svårt att undersöka exaktheten hos AVLExcite-modellen.En annan undersökning som utförts är en numerisk designstudie för att analysera hurdämpningskoefficienterna påverkar responsen. Efter minskning av dämpningsparametrarna visarresultaten att växellådshus och lager har störst inflytande på resultatet. Om mer acceptabla resultatär önskvärda måste framtida studier koncentreras på dessa parametrar för att uppnå mer acceptabladämpningsvärden.

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Neto, Alaor Jose Vieira. "Metodologia de aperfeiçoamento de suspensões veiculares através de modelo virtual em ambiente multicorpos." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-11112013-162224/.

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Entre as etapas do desenvolvimento de automóveis pode-se apontar a definição das características de suas suspensões. A fase de definição da suspensão pode ser dividida dentro do seguinte cenário: a escolha de um determinado tipo de suspensão, os pontos (geometria) e quais os valores de rigidez/amortecimento para todo o sistema irá resultar em um comportamento dinâmico desejado para o veículo, bem como a viabilidade de produção. Além disso, o entendimento da interação entre os parâmetros de suspensão, é crucial para a otimização do desempenho. Este trabalho pretende propor um método para aperfeiçoar a fase de \"tuning\" da suspensão, com foco principal no conforto. O veículo considerado é um caminhão comercial, e entre os seus parâmetros considerados estão rigidezes de molas da cabine e suspensão, amortecimento da suspensão de cabine e curvas do amortecedor da suspensão primária. O modelo virtual do veículo foi desenvolvido em ambiente ADAMS, o qual, previamente à otimização, foi validado contra dados experimentais. Métricas foram especialmente desenvolvidas levando em consideração aspectos subjetivos de conforto veicular, para dessa forma eliminar a variabilidade entre as avaliações subjetivas e análises das simulações. Os resultados mostraram expressivas melhorias no conforto e através de dados experimentais essas melhorias foram confirmadas. Among the development phases of an automotive vehicle one can point out the definition of the characteristics of its suspensions. Suspension definition phase can be understood as the following scenario: given a suspension type, which hard points (geometric) and what values of stiffness/damping for the whole system will result in a desired dynamic behavior for the vehicle as well as production feasibility. Moreover, understanding the iteration among the suspension parameters, even considering just the tuning ones, is crucial for performance optimization. This work intends to propose a method for vehicle tuning characteristics optimization, having as a target the ride comfort. The vehicle considered here is a commercial truck, and among its parameters one considers cabin and suspension springs, cabin dampers and suspension damper curves. A vehicle model was developed in ADAMS environment and prior to the optimization the vehicle was validated against experimental data. Metrics were specially developed to take into account subjective aspects of ride, and, in this way, eliminating the gap between subjective evaluations and simulations analysis. Results showed improvements in ride comfort. The resulting setup was measured and the improvements were confirmed with experimental data.

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Huttenlocher, Luciana de Moraes Gamba. "Estudo do esterçamento nas quatro rodas de um veículo automotivo baseado em duas estratégias de controle da literatura." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-11072018-103217/.

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O comportamento da dinâmica lateral de veículos automotivos com esterçamento nas quatro rodas é estudado com o auxílio de uma ferramenta computacional de modelagem e simulação de sistemas multicorpos. São utilizadas duas estratégias de controle do esterçamento das rodas traseiras para a avaliação de suas principais características. Uma das estratégias esterça as rodas traseiras em função do ângulo de esterçamento do volante, e a outra esterça as rodas traseiras em função do ângulo de esterçamento do volante e da velocidade longitudinal do veículo. O teste utilizado para as análises é a entrada degrau de esterçamento, onde é avaliada a resposta transitória e de regime da aceleração lateral, da velocidade de guinada e do ângulo de rolagem dos veículos. Os resultados das simulações mostram que os veículos com esterçamento nas quatro rodas têm o tempo de resposta da velocidade de guinada maior, e da aceleração lateral e do ângulo de rolagem menores que o veículo convencional. Também apresentam uma diminuição no ganho da aceleração lateral, da velocidade de guinada e do ângulo de rolagem. Além disso apresentam uma característica subesterçante mais acentuada. Essas características são mais evidentes no veículo com estratégia de controle função do esterçamento do volante. Os resultados obtidos correspondem ao comportamento dos veículos com esterçamento nas quatro rodas apresentado na literatura. The lateral dynamic behavior of the automotive vehicles is studied with the aid of a computational tool for multibody systems modeling and simulation. Two rear wheel steering control strategies are used for evaluation of the main four wheel steering characteristics. One strategy steer the rear wheels as a function of the steering wheel angle, and the other one, steer the rear wheels as a function of the steering wheel angle and the speed. The steer step input is the test used, where the lateral acceleration, the yaw rate and the roll angle transient and stead state response are evaluated. The simulation results show that the four wheel steering vehicles have a slower yaw rate time response, and a fast lateral acceleration and roll angle time response than the conventional vehicle. Also four wheel vehicles show a reduction in lateral acceleration, yaw rate a.nd roll angle gain. Moreover they are more understeer than the conventional vehicle. These characteristics are particularly more evident on the vehicle with steer dependent system. The obtained results correspond with four wheel steering vehicles behavior founded in literature.

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Larsson, Tobias. "Multibody dynamic simulation in product development." Doctoral thesis, Luleå, 2001. http://epubl.luth.se/1402-1544/2001/07/index.html.

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Kazemi, Omid. "Comprehensive Tire Model For Multibody Simulations." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338760.

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Tires serve as important components of wheeled vehicles and their analytical modeling has drawn the attention of many researches in the past decades. A high-resolution finite element (FE) tire model contains detailed structural and material characteristics of a tire that exhibit degrees-of-freedom (DoF) in the order of 10⁵ or greater. However, such high-resolution models in their full detail are not practically applicable in multibody dynamic analysis of vehicles and a reduction in their order becomes necessary. In this research different formulations to construct condensed FE tire models suitable for multibody simulations are developed and their characteristics are discussed. In addition, two new and novel forms of substructuring are presented that aim at isolating the contact region of a tire without the need for keeping the boundary DoF which otherwise remain in the reduced system in the standard substructuring procedures. The new substructuring methods provide a great tool in constructing condensed FE tire models with much less total number of DoF compared to cases where a standard substructuring is used. In order to increase the computational efficiency of the condensed FE tire models even further, the possibility of model condensation in the contact region is studied. This research also addresses the applicability of available friction models into the condensed FE tire models. Different formulations of a condensed tire model presented in this research are used to construct several computational models. These models are utilized to simulate certain scenarios and the results are discussed.

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Sun, Yi. "On efficiency of multibody approach in granular dynamics simulations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq20898.pdf.

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Li, Yuwei. "Coupled computational fluid dynamics/multibody dynamics method with application to wind turbine simulations." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4681.

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A high fidelity approach coupling the computational fluid dynamics method (CFD) and multi-body dynamics method (MBD) is presented for aero-servo-elastic wind turbine simulations. The approach uses the incompressible CFD dynamic overset code CFDShip-Iowa v4.5 to compute the aerodynamics, coupled with the MBD code Virtual.Lab Motion to predict the motion responses to the aerodynamic loads. The IEC 61400-1 ed. 3 recommended Mann wind turbulence model was implemented in this thesis into the code CFDShip-Iowa v4.5 as boundary and initial conditions, and used as the explicit wind turbulence for CFD simulations. A drivetrain model with control systems was implemented in the CFD/MBD framework for investigation of drivetrain dynamics. The tool and methodology developed in this thesis are unique, being the first time with complete wind turbine simulations including CFD of the rotor/tower aerodynamics, elastic blades, gearbox dynamics and feedback control systems in turbulent winds. Dynamic overset CFD simulations were performed with the benchmark experiment UAE phase VI to demonstrate capabilities of the code for wind turbine aerodynamics. The complete turbine geometry was modeled, including blades and approximate geometries for hub, nacelle and tower. Unsteady Reynolds-Averaged Navier-Stokes (URANS) and Detached Eddy Simulation (DES) turbulence models were used in the simulations. Results for both variable wind speed at constant blade pitch angle and variable blade pitch angle at fixed wind speed show that the CFD predictions match the experimental data consistently well, including the general trends for power and thrust, sectional normal force coefficients and pressure coefficients at different sections along the blade. The implemented Mann wind turbulence model was validated both theoretically and statistically by comparing the generated stationary wind turbulent field with the theoretical one-point spectrum for the three components of the velocity fluctuations, and by comparing the expected statistics from the simulated turbulent field by CFD with the explicit wind turbulence inlet boundary from the Mann model. The proposed coupled CFD/MBD approach was applied to the conceptual NREL 5MW offshore wind turbine. Extensive simulations were performed in an increasing level of complexity to investigate the aerodynamic predictions, turbine performance, elastic blades, wind shear and atmospheric wind turbulence. Comparisons against the publicly available OC3 simulation results show good agreements between the CFD/MBD approach and the OC3 participants in time and frequency domains. Wind turbulence/turbine interaction was examined for the wake flow to analyze the influence of turbulent wind on wake diffusion. The Gearbox Reliability Collaborative project gearbox was up-scaled in size and added to the NREL 5MW turbine with the purpose of demonstrating drivetrain dynamics. Generator torque and blade pitch controllers were implemented to simulate realistic operational conditions of commercial wind turbines. Interactions between wind turbulence, rotor aerodynamics, elastic blades, drivetrain dynamics at the gear-level and servo-control dynamics were studied, showing the potential of the methodology to study complex aerodynamic/mechanic systems.

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Eiselt, Uwe, and Thomas Kelichhaus. "Dynamische Auslegung von Zahnradgetrieben mittels Mehrkörpersimulation." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21398.

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Auf Grund wachsender Nachfrage der simulativen Beurteilung von Getrieben hinsichtlich Geräuschentwicklung, Vibration und Belastbarkeit, kommt den Berechnungsmethoden immer größere Bedeutung zu. Hier spielen nicht nur die Steifigkeit der Verzahnung, sondern auch die Steifigkeiten der Wellen, Lagerungen und Gehäuse eine wichtige Rolle. Dazu werden unterschiedliche Simulationsmethoden vorgestellt und diese hinsichtlich Genauigkeit, Effizienz und Limitierung bewertet. Ein wichtiger Aspekt ist in diesem Zusammenhang auch die Modellbildung, insbesondere die Ermittlung der Eingabedaten für die Beschreibung der einzelnen Komponenten und deren Verbindungselemente. Die Koppelung des Mehrkörpersystems mit einem speziellen Auslegungstool für Getriebekomponenten ist neben der Multi-Physics-Simulation und der klassischen Mehrkörperdynamik eine Methode, die die Stärken beider Tools verbindet.

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Epple, Alexander. "Methods for increased computational efficiency of multibody simulations." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26532.

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Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2009. Committee Chair: Olivier A. Bauchau; Committee Member: Andrew Makeev; Committee Member: Carlo L. Bottasso; Committee Member: Dewey H. Hodges; Committee Member: Massimo Ruzzene. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Tisell, Claes. "Integration of database technology and multibody system analysis." Doctoral thesis, Stockholm, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3041.

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Burger, Michael [Verfasser]. "Optimal Control of Dynamical Systems: Calculating Input Data for Multibody System Simulation / Michael Burger." München : Verlag Dr. Hut, 2011. http://d-nb.info/1018982701/34.

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Zháňal, Lubor. "Simulace kinematiky a dynamiky vozidlových mechanismů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234269.

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This paper focuses on the kinematic and dynamic numerical simulation of mechanisms by applying a numerical method, and a complex simulation programme built on it, developed by the author. Described are mathematical principles of the numerical method used and also the programming progression of the important parts of the application and its optimization. The final part includes comparative measuring of the accuracy and performance.

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Lacoursière, Claude. "Ghosts and machines : regularized variational methods for interactive simulations of multibodies with dry frictional contacts." Doctoral thesis, Umeå University, Computing Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1143.

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A time-discrete formulation of the variational principle of mechanics is used to provide a consistent theoretical framework for the construction and analysis of low order integration methods. These are applied to mechanical systems subject to mixed constraints and dry frictional contacts and impacts---machines. The framework includes physics motivated constraint regularization and stabilization schemes. This is done by adding potential energy and Rayleigh dissipation terms in the Lagrangian formulation used throughout. These terms explicitly depend on the value of the Lagrange multipliers enforcing constraints. Having finite energy, the multipliers are thus massless ghost particles. The main numerical stepping method produced with the framework is called SPOOK.Variational integrators preserve physical invariants globally, exactly in some cases, approximately but within fixed global bounds for others. This allows to product realistic physical trajectories even with the low order methods. These are needed in the solution of nonsmooth problems such as dry frictional contacts and in addition, they are computationally inexpensive. The combination of strong stability, low order, and the global preservation of invariants allows for large integration time steps, but without loosing accuracy on the important and visible physical quantities. SPOOK is thus well-suited for interactive simulations, such as those commonly used in virtual environment applications, because it is fast, stable, and faithful to the physics.New results include a stable discretization of highly oscillatory terms of constraint regularization; a linearly stable constraint stabilization scheme based on ghost potential and Rayleigh dissipation terms; a single-step, strictly dissipative, approximate impact model; a quasi-linear complementarity formulation of dry friction that is isotropic and solvable for any nonnegative value of friction coefficients; an analysis of a splitting scheme to solve frictional contact complementarity problems; a stable, quaternion-based rigid body stepping scheme and a stable linear approximation thereof. SPOOK includes all these elements. It is linearly implicit and linearly stable, it requires the solution of either one linear system of equations of one mixed linear complementarity problem per regular time step, and two of the same when an impact condition is detected. The changes in energy caused by constraints, impacts, and dry friction, are all shown to be strictly dissipative in comparison with the free system. Since all regularization and stabilization parameters are introduced in the physics, they map directly onto physical properties and thus allow modeling of a variety of phenomena, such as constraint compliance, for instance.Tutorial material is included for continuous and discrete-time analytic mechanics, quaternion algebra, complementarity problems, rigid body dynamics, constraint kinematics, and special topics in numerical linear algebra needed in the solution of the stepping equations of SPOOK.The qualitative and quantitative aspects of SPOOK are demonstrated by comparison with a variety of standard techniques on well known test cases which are analyzed in details. SPOOK compares favorably for all these examples. In particular, it handles ill-posed and degenerate problems seamlessly and systematically. An implementation suitable for large scale performance and accuracy testing is left for future work.

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Beersing-Vasquez, Kiran. "Suturing in Surgical Simulations." Thesis, KTH, Numerisk analys, NA, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-260254.

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The goal of this project is to develop virtual surgical simulation software in order to simulate the suturing and knot tying processes associated with surgical thread. State equations are formulated using Lagrangian mechanics, which is useful for the conservation of energy. Solver methods are developed with theory based in Differential Algebraic Equations (DAEs) which concern governing Ordinary Differential Equations (ODEs) that are constraint with Algebraic Equations (AE). An implicit integration scheme and Newton's method is used to solve the system in each step. Furthermore, a collision response process based on the Linear Complementarity Problem (LCP) is implemented to handle collisions and measure their forces. Models have been developed to represent the different types of objects. A spline model is used to represent the suture and mass-spring model for the tissue. They were both selected for their efficiency and base on real physical properties. The spline model was also chosen as it is continuous and can be evaluated at any point along the length. Other objects are also defined such as rigid bodies. The Lagrangian multiplier method is used to define the constraints in the model. This allows for the construction of complex models. An important constraint is the suturing constraint, which is created when a sufficient force is applied by the suture tip on to the tissue. This constraint allows only a sliding point along the suture to pass through a specific point on the tissue. This results in a virtual suturing model which can be built on for use in surgical simulations. Further investigations would be interesting to increase performance, accuracy and scope of the simulator. Det här projektet syftar till att utveckla mjukvara för virtuell simulering av kirurgi som involverar knytande av suturtråd. Lagranges ekvationer används för att härleda energibevarande tillståndsekvationer. Lösningsmetoderna grundar sig i teori från området Differential-Algebraiska Ekvationer (DAEer), som avser att kontrollera Ordinära Differentialekvationer (ODEer) med algebraiska bivillkor. Ett implicit integrationsschema och Newtons metod används för att lösa systemet i varje steg. Utöver det så implementeras en kollisionsrespons-process baserad på det linjära komplementaritetsproblemet (LCP) för att hantera kollisioner och mäta deras krafter. Modeller har utvecklats för att representera olika typer av objekt. En spline-modell används för att representera suturtråden och ett mass-fjäder system för vävnaden. Valet baserades på deras höga prestanda samt starka anknytning till objektens fysiska egenskaper. Spline-modellen valdes också då dess kontinuitet innebär att den går att evaluera för en godtycklig punkt inom dess domän. Andra objekt, såsom stela kroppar, finns också definierade. Lagrangemultiplikator används för att definiera bivillkor i modellen. Detta tillåter konstruktionen av komplexa modeller. Ett viktigt bivillkor är sutur-bivillkoret som uppstår när tillräcklig kraft från spetsen på den kirurgiska nålen appliceras på vävnaden. Detta bivillkor tillåter att endast en glidande punkt längsmed suturen passerar genom en specifik punkt på vävnaden. Detta resulterar i en virtuell modell för stygn som kan byggas vidare på för användning i kirurgiska simulationer. Det vore intressant med ytterligare undersökningar för att förbättra prestandan, precisionen och simulatorns omfattning.

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Jönsson, Per-Anders. "Dynamic Vehicle-Track Interaction of European Standard Freight Wagons with Link Suspension." Doctoral thesis, KTH, Järnvägsteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4461.

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The link suspension is the most prevailing suspension system for freight wagons in Central and Western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis investigates the dynamic performance of freight wagons and comprises five parts: In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed. The second part focuses on the lateral force-displacement characteristics of the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve the understanding of various mechanisms and phenomena in link suspension systems, a simulation model is developed. In the third part the multibody dynamic simulation model is discussed. The previous freight wagon model developed at KTH is able to explain many of the phenomena observed in tests. In some cases, however, simulated and measured running behaviour differ. Therefore, a new simulation model is presented and validated against on-track test results. The performance of standard two-axle freight wagons is investigated. The most important parameters for the running behaviour of the vehicle are the suspension characteristics. The variation in characteristics between different wagons is large due to geometrical tolerances of the components, wear, corrosion, moisture or other lubrication. The influence of the variation in suspension characteristics and other parameters on the behaviour of the wagon, on tangent track and in curves, is discussed. Finally, suggestions for improvements of the system are made. A majority of the traffic related track deterioration cost originates from freight traffic. With heavier and faster freight trains the maintenance cost is likely to increase. In the fourth part the possibility to improve ride comfort and reduce track forces on standard freight wagons with link suspension is discussed. The variation of characteristics in link suspension running gear is considerable and unfavourable conditions leading to hunting are likely to occur. Supported by on-track tests and multibody dynamic simulations, it is concluded that the running behaviour of two-axled wagons with UIC double-link suspension as well as wagons with link suspension bogies (G-type) can be improved when the running gear are equipped with supplementary hydraulic dampers. Finally in the fifth part the effects of different types of running gear and operational conditions on the track deterioration marginal cost — in terms of settlement in the ballast, component fatigue, wear and RCF — is investigated. Considerable differences in track deterioration cost per produced ton-km for the different types of running gear are observed. Axle load is an important parameter for settlement and component fatigue. Also the height of centre of gravity has significant influence on track deterioration, especially on track sections with high cant deficiency or cant excess. QC 20100802

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Martz, Yannick. "Modélisation et commande de systèmes d'entraînement de bandes flexibles : nouvelles approches à l'aide des éléments finis." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAD016.

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Les systèmes d'entraînement de bandes flexibles sont utilisés dans la production d'une très grande variété de produits du quotidien mais également dans la métallurgie et dorénavant pour la production des nouvelles technologies. L'amélioration des systèmes industriels d'entraînement de bandes est un problème difficile car ils sont de grande dimension, non-linéaires, à paramètres variant et incertains. Ils possèdent un fort couplage entre les différentes parties (mécanique et commande) à cause de la bande qui relie les éléments. Il faut donc améliorer la chaîne de production par une approche pluridisciplinaire. Les objectifs sont de maîtriser les paramètres clés de ces systèmes afin de garantir les cadences de production et les précisions demandées de plus en plus importantes. Il faut également réduire les défauts les plus récurrents, notamment les plis de bande. Or jusqu'à présent seuls des modèles 1D étaient utilisés. Ils sont indispensables pour la synthèse de commande et les études fréquentielles mais ne permettent pas d'étudier des phénomènes complexes tels que les plis de bande. Une nouvelle approche d'étude de ces systèmes est développée. Dans un premier temps, des améliorations de structures de commandes sont proposées. Dans un second temps un modèle 3D par éléments finis utilisant un algorithme de dynamique multicorps flexibles est développé et utilisé pour étudier les plis de bande par comparaison à la théorie classique de prédiction de ces défauts. Dans un troisième temps un simulateur complet est développé comprenant le modèle 3D mécanique par élément finis couplé à la partie commande (co-simulation) Roll-to-Roll systems are used in the manufacturing of a wide variety of everyday products as well as in metallurgy and for the manufacturing of new technologies. The improvement of Roll-to-Roll systems is a difficult problem because they are large, non-linear, with varying and uncertain parameters. They have a coupling between the different parts (mechanical and control) with the help of the web connecting the elements. It is therefore necessary to improve the process line through a multidisciplinary approach. The objectives are to master the key parameters of these systems in order to guarantee the manufacturing rates and the more important accuracies requested. It is also necessary to reduce or remove the most recurring defects such as web wrinkles. Until now, only 1D models were used. They are essential for control synthesis and frequency studies but they do not allow to study complex phenomena such as web wrinkles. A new approach for studying these systems is developed. First, improvements of control structures are proposed. Secondly, a 3D finite element model using a flexible multibody dynamics algorithm is developed, used in this work to study web wrinkles and compared to the classical prediction theory of these defects. Finally, a complete simulator is developed including the mechanical 3D model by finite element coupled to the control part (co-simulation)

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El, Azzouzi Khalid. "Modélisation et simulation numérique à l’échelle des fibres du comportement dynamique d’un multifilament unidirectionnel en placement de fibres robotisé." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0027.

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Le comportement mécanique d’un fil de carbone en compression transverse est caractérisé par des déplacements relatifs importants entre fibres, ce qui lui confère un comportement fortement non-linéaire lié aux contacts inter-fibres. Le caractère multi-échelle de la structure fibreuse rend problématique la caractérisation du comportement mécanique du fil de carbone utilisé dans le procédé de placement de fibres sèches automatisé. La complexité de la modélisation mécanique de ce milieu fibreux à l’échelle des fibres est due au fait que la forte non-linéarité mécanique dépend en grande partie de la configuration géométrique des fibres, des interactions de contact-frottement entre elles et le contexte dynamique de la dépose. Le couplage fort entre chargements et modes de déformation dans les différentes directions et l’évolution de la microstructure, qu’il est bien difficile d’appréhender, accentuent fortement la complexité de la modélisation d’une telle structure fibreuse. Le travail de la thèse s’inscrit dans le cadre de l’optimisation du moyen de dépose robotisé de fils secs avec une source de chaleur par laser. Afin de comprendre le comportement thermo-mécanique du fil au cours de la dépose, un modèle dynamique a été développé pour simuler un milieu fibreux en interaction. Le but est de pouvoir prédire le réarrangement des fibres dans un fil sous sollicitation, ainsi que l’évolution des points de contact entre fibres. Ce travail est une première étape vers l’objectif final qui est de définir les paramètres procédés par rapport à la nature des fils secs déposés permettant d’obtenir une préforme de bonne qualité avec une vitesse de dépose élevée The mechanical behavior of the carbon tow in lateral pressure characterized by the relative movement between fibers giving it a non-linear behavior because of the contact inter-fibers. The fact that the fibrous structure of the tow makes it difficult to characterize its mechanical behavior during the automated placement. The complexity of the mechanical modeling of this fibrous media at fiber scale is due to the fact that the mechanical non-linearity depends in large part to the geometric configuration of fibers, the friction between fibers and also the dynamic environment of the placement. The mechanical modeling complexity is a consequence of the tight coupling between loading and deformation directions modifying the microstructure. This thesis is in keeping with the parameter optimization of the Automated Dry Fiber Placement process with a laser heat source. In order to improve understanding the thermos-mechanical behavior of tow during placement, a dynamic model has been developed to simulate the interaction between fibers. The aim is to be able to predict the geometric configuration of fibers under loading, as well as the position of the contact points. These works are the first step to achieving the objective of identifying and optimizing process parameters in order to increase the lay down speed as well as the quality of the preform

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"Numerical simulations of constrained multibody systems." Thesis, 2005. http://library.cuhk.edu.hk/record=b6073984.

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As the second task of this thesis, we shall propose some mathematical model to simulate the movement of a floating bridge under some moving loadings. The floating bridge system consists of three parts, i.e. river (fluid), floating bridge (multibody system) and vehicles (load) which pass the bridge. Our objective is to find the motion and dynamical responses of the floating bridge with a truck or tracklayer passing on it. The floating bridge is a system of steel rectangular boxes which can be seen as rigid bodies connected by some kinematic joints. In fact, such system is a fluid-structure coupled system and one must treat the governing equations for the floating bridge and fluid, i.e. Euler-Lagrange equations and Navier-Stokes equations, simultaneously. In our work, we apply the one-leg method and operator splitting arbitrary Lagrangian-Eulerian method to solve the coupled system. When performing dynamical analysis of a constrained mechanical system, a set of index-3 differential algebraic equations, i.e. Euler-Lagrange equations, are often needed to describe the time evolution of the mechanical system. In this thesis, we apply one-leg multi-step methods to integrate the DAEs directly. To overcome some difficulties leading to certain numerical instabilities, a velocity elimination technique is applied to generate a framework that the position and velocity profiles can be obtained in two separate stages: only the position variables and Lagrange multipliers take part in the convergent nonlinear iterations at each time step while the velocity is calculated by the multi-step formula directly without any iteration. The framework is constructed in a manner such that it satisfies all the constraints at the position level and involves variables as few as possible during the iteration. Some convergence analysis are presented and good stability and high efficiency can be seen through the experiments of some benchmark problems. Zhao Yubo. "July 2005." Adviser: Zou Jun. Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0310. Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. Includes bibliographical references (p. 244-276). Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. Abstracts in English and Chinese. School code: 1307.

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Marques, Pedro Filipe Lima. "Frictional contacts in multibody dynamics." Master's thesis, 2015. http://hdl.handle.net/1822/37625.

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Dissertação de mestrado integrado em Engenharia Mecânica This work has as primary goal to study the influence of friction modeling on the dynamic behavior of mechanical systems. In this sense, an extensive literature review was conducted in order to present the main phenomena due to friction generated between two contacting surfaces. Furthermore, a comprehensive study of different friction modeling approaches was carried in order to explain the main characteristics of the most relevant static and dynamic friction models. The comparison between different methodologies of friction modelling is presented in two distinct phases. The first consists in a simple system with one degree of freedom where friction plays a major role in the behavior of the system. The second phase involves more complex three-dimensional mechanical systems, where just a small part of the presented models is employed. In the latter phase, it is analyzed a kinematic translational joint with friction, where the friction force is implicitly calculated in the resolution of the equations of motion, and a spatial revolute joint with axial and radial clearance where friction is treated as an external force acting on the system. Due to the use of multibody systems in the mentioned examples, it was necessary to introduce the three-dimensional formulation for their dynamic analysis, which in this case is based on the Newton-Euler equations. Some methods for solving the equations of motion are also discussed, as well as their efficiency and accuracy. The dynamic simulations of multibody systems performed in the context of this work were carried out using MUBODYNA (Flores, 2012). The main conclusion of this study is that friction plays a key role in the behavior of multibody systems due to its energy dissipation properties. The main differences between the existing models are in the vicinity of zero relative velocity, thus the disparities occur during motion reversal. Este trabalho tem como objetivo principal estudar a influência da modelação do atrito no comportamento dinâmico de sistemas mecânicos com múltiplos corpos. Nesse sentido, uma vasta pesquisa bibliográfica foi efetuada, de modo a apresentar quais os principais fenómenos produzidos devido ao atrito gerado entre duas superfícies em contacto. Para além disso, um estudo abrangente sobre diferentes abordagens para o cálculo da força de atrito foi realizado de modo a explanar as características dos modelos de atrito mais importantes. A comparação entre as diferentes metodologias de modelação de atrito é apresentada em duas fases distintas. A primeira consiste na utilização de um sistema simples com um grau de liberdade onde o atrito tem papel preponderante no comportamento sistema. A segunda fase considera sistemas mecânicos tridimensionais mais complexos, onde apenas é estudada uma pequena parte dos modelos apresentados. Nesta fase, analisa- se uma junta cinemática de translação com atrito, onde o atrito é calculado implicitamente na resolução das equações do movimento, e uma junta de revolução com folga radial e axial onde o atrito é tratado como uma força externa que atua no sistema. Devido à utilização de sistemas multicorpo nos exemplos apresentados, foi necessário introduzir a formulação tridimensional para a sua análise dinâmica, que neste caso tem por base as equações Newton-Euler. Alguns métodos para a resolução das equações do movimento também são discutidos, bem como as suas eficiência e precisão. As simulações dinâmicas realizadas no âmbito deste trabalho foram executadas usando o código MUBODYNA (Flores, 2012). A principal conclusão deste trabalho é de que o atrito tem um papel fundamental no comportamento de sistemas multicorpo devido às suas propriedades de dissipação de energia. As principais diferenças entre os modelos existentes encontram-se na vizinhança da velocidade relativa nula, posto isto, estas acontecem durante inversões de sentido.

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Gonthier, Yves. "Contact Dynamics Modelling for Robotic Task Simulation." Thesis, 2007. http://hdl.handle.net/10012/3416.

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This thesis presents the theoretical derivations and the implementation of a contact dynamics modelling system based on compliant contact models. The system was designed to be used as a general-purpose modelling tool to support the task planning process space-based robot manipulator systems. This operational context imposes additional requirements on the contact dynamics modelling system beyond the usual ones of fidelity and accuracy. The system must not only be able to generate accurate and reliable simulation results, but it must do it in a reasonably short period of time, such that an operations engineer can investigate multiple scenarios within a few hours. The system is easy to interface with existing simulation facilities. All physical parameters of the contact model can be identified experimentally or can be obtained by other means through analysis or theoretical derivations based on the material properties. Similarly, the numerical parameters can be selected automatically or by using heuristic rules that give an indication of the range of values that would ensure that the simulations results are qualitatively correct. The contact dynamics modelling system is comprised of two contact models. On one hand, a point contact model is proposed to tackle simulations involving bodies with non-conformal surfaces. Since it is based on Hertz theory, the contacting surfaces must be smooth and without discontinuity, i.e., no corners or sharp edges. The point contact model includes normal damping and tangential friction and assumes the contact surface is very small, such that the contact force is assumed to be acting through a point. An expression to set the normal damping as a function of the effective coefficient of restitution is given. A new seven-parameter friction model is introduced. The friction model is based on a bristle friction model, and is adapted to the context of 3-dimensional frictional impact modelling with introduction of load-dependent bristle stiffness and damping terms, and with the expression of the bristle deformation in vectorial form. The model features a dwell-time stiction force dependency and is shown to be able to reproduce the dynamic nature of the friction phenomenon. A second contact model based on the Winkler elastic foundation model is then proposed to deal with a more general class of geometries. This so-called volumetric contact model is suitable for a broad range of contact geometries, as long as the contact surface can be approximated as being flat. A method to deal with objects where this latter approximation is not reasonable is also presented. The effect of the contact pressure distribution across the contact surface is accounted for in the form of the rolling resistance torque and spinning friction torque. It is shown that the contact forces and moments can be expressed in terms of the volumetric properties of the volume of interference between the two bodies, defined as the volume spanned by the intersection of the two undeformed geometries of the colliding bodies. The properties of interest are: the volume of the volume of interference, the position of its centroid, and its inertia tensor taken about the centroid. The analysis also introduces a new way of defining the contact normal; it is shown that the contact normal must correspond to one of the eigenvectors of the inertia tensor. The investigation also examines how the Coulomb friction is affected by the relative motion of the objects. The concept of average surface velocity is introduced. It accounts for both the relative translational and angular motions of the contacting surfaces. The average surface velocity is then used to find dimensionless factors that relate friction force and spinning torque caused by the Coulomb friction. These latter factors are labelled the Contensou factors. Also, the radius of gyration of the moment of inertia of the volume of interference about the contact normal was shown to correlate the spinning Coulomb friction torque to the translational Coulomb friction force. A volumetric version of the seven-parameter bristle friction model is then presented. The friction model includes both the tangential friction force and spinning friction torque. The Contensou factors are used to control the behaviour of the Coulomb friction. For both contact models, the equations are derived from first principles, and the behaviour of each contact model characteristic was studied and simulated. When available, the simulation results were compared with benchmark results from the literature. Experiments were performed to validate the point contact model using a six degrees-of-freedom manipulator holding a half-spherical payload, and coming into contact with a flat plate. Good correspondence between the simulated and experimental results was obtained.

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Suryakumar, Vishvas Samuel. "A Finite Element-Multibody Dynamics Co-simulation Methodology Applied to FAST." Thesis, 2013. http://hdl.handle.net/1969.1/149585.

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A co-simulation methodology is explored whereby a finite element code and a multi-body dynamics code featuring flexible cantilevered beams can be coupled and interactively executed. The floating frame of reference formulation is used to develop the equations of motion. The floating frame is fixed at the blade root. Such a formulation results in ordinary differential equations without added algebraic constraints. A variety of loose coupling and tight coupling schemes are examined for this problem. To synchronize the coupling variables, a Gauss-Seidel type iterative algorithm is used. The resulting fixed-point iterations are accelerated using Aitken’s adaptive relaxation technique. The methodology is evaluated for FAST, a wind turbine aeroelastic simulation code developed by NREL. As with FAST, many multi-body codes which can model flexibility employ modal methods. A proposed addition for FAST to simulate flexible effects using a finite element method module offers a potential to include a variety of non-linearities and also provides possibilities for using a high-fidelity aerodynamics module. The coupling schemes are compared and their applicability and limitations for different scenarios are pointed out. Results validating the approach are provided.

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Chen, Chi-Chuan, and 陳啟專. "Multibody dynamics Simulation of 3-D human Gait during swing Phase." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/77770651006144105062.

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Carvalho, André Rui Dantas. "Multibody dynamics modelling and analysis of the human hand." Thesis, 2007. http://hdl.handle.net/1828/248.

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This thesis presents a simulation model for the dynamics of the human hand for application to an anthropomorphic prosthesis. The Articulated Body Algorithm (ABA) algorithm was selected to model the dynamics of a tree type robotic structure. The ABA is a numerical Newton-Euler based algorithm that solves the forward dynamics (obtaining the joint accelerations from the applied torques and forces) for a joint-link model. The main advantage of this algorithm resides in the analysis of the system link by link rather than the entire system analysis. This feature enables the implementation of a computationally efficient code and makes the algorithm generic enough to be applied to almost any robotic structure, with minimal additional effort. Furthermore, as the basic algorithm only handles serial structures, it was modified to include the effect of the gravity, loads on the end-effector, elasticity and damping at the joints, the generalization to tree-type structures, and, finally, the inclusion of impact analysis.

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"Multibody dynamics based simulation studies of escapement mechanisms in mechanical watch movement." 2008. http://library.cuhk.edu.hk/record=b5893587.

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Fu, Kin Chung Denny. Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. Includes bibliographical references (leaves 119-123). Abstracts in English and Chinese. Abstract --- p.i 摘要 --- p.iii Acknowledgements --- p.iv Table of Contents --- p.v List of Figures --- p.viii List of Tables --- p.xi Chapter Chapter 1 --- Introduction --- p.1 Chapter 1.1 --- Objective --- p.1 Chapter 1.2 --- Fundamental knowledge of multibody dynamics --- p.2 Chapter 1.3 --- Escapement mechanisms --- p.5 Chapter 1.3.1 --- Time keeping accuracy and stability factors --- p.7 Chapter 1.3.2 --- Estimations of moment of inertia --- p.9 Chapter 1.3.3 --- Other simulations and analyses --- p.15 Chapter 1.4 --- Thesis outlines --- p.15 Chapter 1.5 --- Chapter summary --- p.17 Chapter Chapter 2 --- Multibody Dynamics --- p.18 Chapter 2.1 --- The unilateral corner law of impact --- p.18 Chapter 2.2 --- The Coulomb's friction --- p.19 Chapter 2.3 --- "Slip, stick, and slip reversal phenomena" --- p.20 Chapter 2.4 --- The coefficients of restitution --- p.20 Chapter 2.5 --- Ways of formulating multiple contacts --- p.22 Chapter 2.6 --- Integration procedure --- p.22 Chapter 2.7 --- The P. Pfeiffer and Ch. Glocker's approach --- p.23 Chapter 2.7.1 --- Kinematics calculation --- p.23 Chapter 2.7.2 --- Configuration index --- p.26 Chapter 2.7.3 --- Motion without contact --- p.27 Chapter 2.7.4 --- Motion for detachment and slip-stick transition and LCP formulation --- p.27 Chapter 2.7.5 --- Motion for impact and LCP formulation --- p.37 Chapter 2.8 --- Solving LCP --- p.50 Chapter 2.9 --- Chapter summary --- p.52 Chapter Chapter 3 --- Development of the Simulation Tool --- p.54 Chapter 3.1 --- Kinematics calculation --- p.54 Chapter 3.1.1 --- Geometric definitions --- p.55 Chapter 3.1.2 --- Line-to-line contact --- p.59 Chapter 3.1.3 --- Arc-to-line contact --- p.62 Chapter 3.1.4 --- Kinematics calculation procedures --- p.67 Chapter 3.2 --- Obtaining the solutions --- p.72 Chapter 3.3 --- Revised numerical treatment for LCP solving --- p.73 Chapter 3.4 --- Integration procedure of simulation --- p.74 Chapter 3.5 --- Verification example --- p.76 Chapter 3.5.1 --- Classical mechanics approach --- p.76 Chapter 3.5.2 --- Pre-calculation before application --- p.79 Chapter 3.5.3 --- Simulation results --- p.81 Chapter 3.6 --- Chapter summary --- p.83 Chapter Chapter 4 --- Application to Swiss Lever Escapement --- p.84 Chapter 4.1 --- Working principle of Swiss lever escapement --- p.84 Chapter 4.2 --- Simulation of Swiss lever escapement --- p.87 Chapter 4.2.1 --- Pre-calculation of kinematics --- p.88 Chapter 4.2.2 --- Simulation results --- p.89 Chapter 4.3 --- More simulations --- p.102 Chapter 4.3.1 --- Theoretical optimal peak amplitudes --- p.102 Chapter 4.3.2 --- Simulation of coaxial escapement --- p.103 Chapter 4.3.3 --- Simulations with different simulation parameters --- p.109 Chapter 4.3.4 --- Relation of input complexity and computational time --- p.111 Chapter 4.4 --- Chapter summary --- p.113 Chapter Chapter 5 --- Conclusions and Future works --- p.114 Chapter 5.1 --- Conclusions --- p.114 Chapter 5.2 --- Future works --- p.117 Bibliography --- p.119

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Khakpour, Zahra. "Multibody dynamics model of a full human body for simulating walking." Thesis, 2017. https://doi.org/10.7912/C29S86.

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Indiana University-Purdue University Indianapolis (IUPUI) Khakpour, Zahra M.S.M.E., Purdue University, May 2017. Multibody Dynamics Model of A Full Human Body For Simulating Walking, Major Professor: Hazim El-Mounayri. Bipedal robotics is a relatively new research area which is concerned with creating walking robots which have mobility and agility characteristics approaching those of humans. Also, in general, simulation of bipedal walking is important in many other applications such as: design and testing of orthopedic implants; testing human walking rehabilitation strategies and devices; design of equipment and facilities for human/robot use/interaction; design of sports equipment; and improving sports performance & reducing injury. One of the main technical challenges in that bipedal robotics area is developing a walking control strategy which results in a stable and balanced upright walking gait of the robot on level as well as non-level (sloped/rough) terrains. In this thesis the following aspects of the walking control strategy are developed and tested in a high-fidelity multibody dynamics model of a humanoid body model: 1. Kinematic design of a walking gait using cubic Hermite splines to specify the motion of the center of the foot. 2. Inverse kinematics to compute the legs joint angles necessary to generate the walking gait. 3. Inverse dynamics using rotary actuators at the joints with PD (Proportional-Derivative) controllers to control the motion of the leg links. The thee-dimensional multibody dynamics model is built using the DIS (Dynamic Interactions Simulator) code. It consists of 42 rigid bodies representing the legs, hip, spine, ribs, neck, arms, and head. The bodies are connected using 42 revolute joints with a rotational actuator along with a PD controller at each joint. A penalty normal contact force model along with a polygonal contact surface representing the bottom of each foot is used to model contact between the foot and the terrain. Friction is modeled using an asperity-based friction model which approximates Coulomb friction using a variable anchor-point spring in parallel with a velocity dependent friction law. In this thesis, it is assumed in the model that a balance controller already exists to ensure that the walking motion is balanced (i.e. that the robot does not tip over). A multi-body dynamic model of the full human body is developed and the controllers are designed to simulate the walking motion. This includes the design of the geometric model, development of the control system in kinematics approach, and the simulation setup.

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Vlasenko, Dmitry [Verfasser]. "Komponentenorientierende Methode zur Simulation von Mehrkörpersystemen = Component oriented method for simulation of multibody dynamics / von: Vlasenko Dmitry." 2006. http://d-nb.info/97878944X/34.

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Uchida, Thomas Kenji. "Real-time Dynamic Simulation of Constrained Multibody Systems using Symbolic Computation." Thesis, 2011. http://hdl.handle.net/10012/5844.

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The main objective of this research is the development of a framework for the automatic generation of systems of kinematic and dynamic equations that are suitable for real-time applications. In particular, the efficient simulation of constrained multibody systems is addressed. When modelled with ideal joints, many mechanical systems of practical interest contain closed kinematic chains, or kinematic loops, and are most conveniently modelled using a set of generalized coordinates of cardinality exceeding the degrees-of-freedom of the system. Dependent generalized coordinates add nonlinear algebraic constraint equations to the ordinary differential equations of motion, thereby producing a set of differential-algebraic equations that may be difficult to solve in an efficient yet precise manner. Several methods have been proposed for simulating such systems in real time, including index reduction, model simplification, and constraint stabilization techniques. In this work, the equations of motion are formulated symbolically using linear graph theory. The embedding technique is applied to eliminate the Lagrange multipliers from the dynamic equations and obtain one ordinary differential equation for each independent acceleration. The theory of Gröbner bases is then used to triangularize the kinematic constraint equations, thereby producing recursively solvable systems for calculating the dependent generalized coordinates given values of the independent coordinates. For systems that can be fully triangularized, the kinematic constraints are always satisfied exactly and in a fixed amount of time. Where full triangularization is not possible, a block-triangular form can be obtained that still results in more efficient simulations than existing iterative and constraint stabilization techniques. The proposed approach is applied to the kinematic and dynamic simulation of several mechanical systems, including six-bar mechanisms, parallel robots, and two vehicle suspensions: a five-link and a double-wishbone. The efficient kinematic solution generated for the latter is used in the real-time simulation of a vehicle with double-wishbone suspensions on both axles, which is implemented in a hardware- and operator-in-the-loop driving simulator. The Gröbner basis approach is particularly suitable for situations requiring very efficient simulations of multibody systems whose parameters are constant, such as the plant models in model-predictive control strategies and the vehicle models in driving simulators.

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47

Ahmadi, Ghoohaki Shahriar. "High-fidelity modeling of a backhoe digging operation using an explicit multibody dynamics finite element code with integrated discrete element method." Thesis, 2013. http://hdl.handle.net/1805/3650.

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Indiana University-Purdue University Indianapolis (IUPUI) In this thesis, a high- fidelity multibody dynamics model of a backhoe for simulating the digging operation is developed using the DIS (Dynamic Interactions Simulator)multibody dynamics software. Sand is used as a sample digging material to illustrate the model. The backhoe components (such as frame, manipulators links,track segments, wheels and sprockets) are modeled as rigid bodies. The geometry of the major moving components of the backhoe is created using the Pro/E solid modeling software. The components of the backhoe are imported to DIS and connected using joints (revolute, cylindrical and prismatic joints). Rotary and linear actuators along with PD (Proportional-Derivative) controllers are used to move and steer the backhoe and to move the backhoes manipulator in the desired trajectory. Sand is modeled using cubic shaped particles that can come into contact with each other, the backhoes bucket and ground. A cubical sand particle contact surface is modeled using eight spheres that are rigidly glued to each other to form a cubical shaped particle, The backhoe and ground surfaces are modeled as polygonal surfaces. A penalty technique is used to impose both joint and normal contact constraints (including track-wheels, track-terrain, bucket-particles and particles-particles contact). An asperity-based friction model is used to model joint and contact friction. A Cartesian Eulerian grid contact search algorithm is used to allow fast contact detection between particles. A recursive bounding box contact search algorithm is used to allow fast contact detection for polygonal contact surfaces and is used to detect contact between: track and ground; track and wheels; bucket and particles; and ground and particles. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The sand model is validated using a conical hopper sand flow experiment in which the sand flow rate during discharge and the angle of repose of the resulting sand pile are experimentally measured. The results of the conical hopper simulation are compared with previously published experimental results. Parameter studies are performed using the sand model to study the e ffects of the particle size and the orifi ces diameter of the hopper on the sand pile angle of repose and sand flow rate. The sand model is integrated with the backhoe model to simulate a typical digging operation. The model is used to predict the manipulators actuator forces needed to dig through a pile of sand. Integrating the sand model and backhoe model can help improving the performance of construction equipment by predicting, for various vehicle design alternatives: the actuator and joint forces, and the vehicle stability during digging.

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Silva, Ivo Miguel Monteiro. "Co-simulation of the lumbar intervertebral discs through finite element method and multibody systems dynamics." Master's thesis, 2014. http://hdl.handle.net/1822/34487.

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Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Biomateriais, Reabilitação e Biomecânica) Degenerative disc disease is the most common cause of low back pain, affecting about 70-85% of the general population at some time in life. This evidence became the motivation for this work, whose purpose is to analyze the geometric sensibility of a finite element model of the lumbar intervertebral disc, and to optimize a three-dimensional multibody lumbar spine model. Throughout the years, the development of mathematical spine models using finite element and multibody system formulations have evolved greatly. Nowadays, human spine models are able to reproduce with accuracy the biomechanical response of the different anatomical features of the spine. At an initial stage, a lumbar partial motion segment model and respective finite element formulation are briefly described. The model is composed by two partial vertebrae connected by an intervertebral disc. A geometric sensibility analysis of the model is performed by varying its wedge angle and average height, and simulating the models under different types of incremental loads, using a home-developed finite element solver. From this analysis, different mechanical aspects of the intervertebral disc’s behavior are obtained, such as volume and pressure variations of both nucleus pulposus and annulus fibrosus, quantity and grade of annulus’ fibers stretching, and range of angular motion. The respective results prove that both wedge angle and average height variations have significant influence on the intervertebral discs’ behavior under loading. Thereafter, a general concept of multibody system is defined, and a description of a multibody lumbar spine model is presented. The model is composed by six rigid bodies, representing the lumbar vertebrae and the sacrum, and fifty spring/damper sets, modeling the intervertebral discs and lumbar ligaments. Based on the angles of the different lumbar levels, the model is optimized by implementing the results of the previous geometric sensibility analysis. The model is validated using experimental data found in the literature, revealing identical behavior during lateral flexion and axial rotation. Subsequently, the application of the model is performed by applying different types of loads and analyze their distribution along the lumbar spine levels. The results indicate that the last two lumbar levels are more susceptible to mechanical stresses, being the tendency to degeneration of these discs probably related to this fact. A doença degenerativa dos discos intervertebrais é a causa mais comum de dor lombar, afetando cerca de 70-85% de toda a população em alguma altura durante a vida. Esta evidência tornou-se a motivação para a realização deste trabalho, cujo objetivo é analisar a sensibilidade geométrica de um modelo de elementos finitos de um disco intervertebral lombar, e otimizar um modelo multi-corpo tridimensional da coluna lombar. Ao longo dos anos, o desenvolvimento de modelos matemáticos da coluna usando formulações de elementos finitos e sistemas multi-corpo tem evoluído bastante. Atualmente, os modelos da coluna humana são capazes de reproduzir com precisão as respostas biomecânicas dos diferentes componentes anatómicos da coluna. Numa fase inicial, é sucintamente descrito um modelo de um segmento móvel lombar parcial e a respetiva formulação de elementos finitos. O modelo é composto por duas vértebras parciais conectadas por um disco intervertebral. Uma análise da sensibilidade geométrica do modelo é realizada através da variação do seu ângulo e da sua altura média, e, recorrendo a um programa de elementos finitos desenvolvido internamente, os modelos foram simulados com a aplicação de diferentes tipos de cargas. Desta análise, os diferentes aspetos mecânicos do comportamento do disco são obtidos, como a variação de volume e pressão do anel fibroso e do núcleo pulposo, bem como a quantidade e grau de alongamento das fibras do anel, e a amplitude de movimento. Os respetivos resultados provam que a variação do ângulo e da altura média têm influência considerável no comportamento dos discos intervertebrais quando sujeitos a cargas. Após isso, é definido o conceito geral de sistema multi-corpo, e é apresentada uma descrição do modelo multi-corpo da coluna lombar. O modelo é composto por seis corpos rígidos, representando as vértebras lombares e o sacro, e cinquenta conjuntos mola/amortecedor, modelando os discos intervertebrais e os ligamentos lombares. Com base nos ângulos dos diferentes níveis lombares, o modelo é otimizado através da implementação dos resultados da análise da sensibilidade geométrica, obtidos anteriormente. O modelo é validado usando resultados experimentais encontrados na literatura, revelando comportamento idêntico na flexão lateral e rotação axial. Subsequentemente, a aplicação do modelo é realizada através da aplicação de diferentes tipos de cargas e analisando a sua distribuição ao longo dos níveis da coluna lombar. Os resultados indicam que os últimos níveis lombares são mais suscetíveis a esforços mecânicos, podendo estar a tendência para a degeneração destes discos relacionada com este fato.

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49

Wang, Lei. "Multibody Dynamics Using Conservation of Momentum with Application to Compliant Offshore Floating Wind Turbines." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11740.

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Environmental, aesthetic and political pressures continue to push for siting off-shore wind turbines beyond sight of land, where waters tend to be deeper, and use of floating structures is likely to be considered. Savings could potentially be realized by reducing hull size, which would allow more compliance with the wind thrust force in the pitch direction. On the other hand, these structures with large-amplitude motions will make dynamic analysis both more challenging and more critical. Prior to the present work, there were no existing dynamic simulation tools specifically intended for compliant wind turbine design. Development and application of a new computational method underlying a new time-domain simulation tool is presented in this dissertation. The compliant floating wind turbine system is considered as a multibody system including tower, nacelle, rotor and other moving parts. Euler's equations of motion are first applied to the compliant design to investigate the large-amplitude motions. Then, a new formulation of multibody dynamics is developed through application of the conservation of both linear momentum and angular momentum to the entire system directly. A base body is prescribed within the compliant wind turbine system, and the equations of motion (EOMs) of the system are projected into the coordinate system associated with this body. Only six basic EOMs of the system are required to capture 6 unknown degrees of freedom (DOFs) of the base body when mechanical DOFs between contiguous bodies are prescribed. The 6 x 6 mass matrix is actually composed of two decoupled 3 x 3 mass matrices for translation and rotation, respectively. Each element within the matrix includes the inertial effects of all bodies. This condensation decreases the coupling between elements in the mass matrix, and so minimizes the computational demand. The simulation results are verified by critical comparison with those of the popular wind turbine dynamics software FAST. The new formulation is generalized to form the momentum cloud method (M- CM), which is particularly well suited to the serial mechanical N-body systems connected by revolute joints with prescribed relative rotation. The MCM is then expanded to multibody systems with more complicated joints and connection types.

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50

Deepak, R. Sangamesh. "A New Insight Into Recursive Forward Dynamics Algorithm And Simulation Studies Of Closed Loop Systems." Thesis, 2006. http://hdl.handle.net/2005/449.

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Rigid multibody systems have been studied extensivley due to its direct application in design and analysis of various mechanical systems such as robots and spacecraft structures. The dynamics of multibody system is governed by its equations of motion and various terms associated with it, such as the mass matrix, the generalized force vector, are well known..Forward dynamics algorithms play an important role in the simulation of multibody systems and the recursive forward dynamics algorithm for branched multibody systems is very popular. The recursive forward dynamic algorithm is highly eﬃcient algorithm with O(n) computational complexity and scores over other algorithms when number of rigid bodies n in the system is very large. The algorithm involves ﬁnding an important mass matrix, which has been popularly termed as articulated body inertia (AB inertia). To ﬁnd ijth term of any general mass matrix, we separately give virtual change to ith and jth generalized coordinates. At each point of the multibody system, the dot product of the resulting virtual displacements are taken with each other and eventually integrated over the entire multibody system, weighted by the mass. This quantity divided by the virtual changes in ith and jth coordinates gives the ijth element of the mass matrix. This is one of the fundamental ways of looking at the mass matrix. However, in literature, the AB inertia is obtained as a result of mathematical manipulation and its physical or geometrical signiﬁcance from the above view point is not clear. In this thesis we present a more geometric and physical explanation for the AB inertia. The main step is to obtain a new set of generalized coordinates which relate directly to the AB inertia. We have also shown the equivalence of our method with existing methods. A comprehensive treatement on change of generalized coordinates and its eﬀect on equations of motion has also been presented as preliminaries. The second part of the thesis deals with closed loop multibody systems.A few years ago an iterative algorithm called the sequential regularization method (SRM) was proposed for simulation of closed loop multibody systems with attractive claims on its eﬃciency. In literature we ﬁnd that this algorithm has been implemented and studied only for planar multibody systems. As a part of the thesis work, we have developed a C-programming language code which can simulate 3-dimensional spatial multibody systems using the SRM algorithm. The programme can also perform simulation using a relatively eﬃcient Conventional algorithm having O(n+m3) complexity, where m denotes number of closed loop constraints. Simulation studies have been carried out on a few multibody systems using the two algorithms. Some of the results have been also been validated using the commercial simulation package -ADAMS. As a result of our simulation studies, we have detected certain points, after which the solution from SRM loses it convergence. More study is required to understand this lack of convergence.

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Dissertations / Theses on the topic 'Multibody Dynamics Simulation'

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