Academic literature on the topic 'Variable pitch spring'
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Journal articles on the topic "Variable pitch spring"
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Qiu, Donghai, Manuel Paredes, and Sébastien Seguy. "Variable pitch spring for nonlinear energy sink: Application to passive vibration control." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 2 (2018): 611–22. http://dx.doi.org/10.1177/0954406218761485.
Full textAbstract:
This paper aims to propose a generalized methodology for designing a novel nonlinear energy sink with variable pitch springs. To this end, a generic model of the nonlinear energy sink system providing the nonlinearity of pure cubic stiffness is introduced. Key features of the model include: (i) specifically sizing two variable pitch springs to provide the force polynomial components with only linear and cubic terms; (ii) pre-compressing two springs at the transition point to produce smooth nonlinear force characteristics; (iii) adding a negative stiffness mechanism to counterbalance the linear term. To generate the variable pitch spring, design parametrization is implemented. The type of shape and the pitch distribution adopted for the spring are shown to fit the objective force–displacement function well. To validate the concept, a special sized nonlinear energy sink system is developed. Identification of the force–displacement relation and experiments for the whole system embedded on an electrodynamic shaker are studied. The results show that this nonlinear energy sink can not only output the anticipated nonlinearity, but can also produce energy pumping to protect the primary system in a large band of frequencies, thus making it practical for the application of passive vibration control.
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Lin, Yuyi, and Albert P. Pisano. "General Dynamic Equations of Helical Springs With Static Solution and Experimental Verification." Journal of Applied Mechanics 54, no. 4 (1987): 910–17. http://dx.doi.org/10.1115/1.3173138.
Full textAbstract:
The general dynamic equations of helical compression springs with circular wire cross section, variable pitch angle, and variable helix radius are derived. The equations are formulated by Hamilton’s principle and a variational method. In contrast to previous studies, the effects of coil flexure bending, variable pitch angle and variable helix radius are taken into account. The general equations are shown to agree with dynamic equations found in literature when the general equations are reduced to simplified forms. For a specific helical spring and static loading, the equations are solved with both the predicted radial expansion and the predicted longitudinal spring compression force in excellent agreement with experimental data.
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Lin, Yuyi, and Albert P. Pisano. "The Differential Geometry of the General Helix as Applied to Mechanical Springs." Journal of Applied Mechanics 55, no. 4 (1988): 831–36. http://dx.doi.org/10.1115/1.3173729.
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In order to improve the performance of helical springs, such as increasing the fatigue life and suppressing resonance, variable pitch angle and variable helix radius may be incorporated into the helical spring geometry. Employing the tool of differential geometry, new and complete formulae of curvature, torsion, and spring force are derived. It is shown that these formulae are more general and accurate than Kelvin’s curvature and torsion formulae, than commonly used force formulae (Wahl, 1963). Possible simplifications to the complete formulae and the corresponding errors introduced are both discussed and compared with experimental data.
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Ji, Jie, Yun Wu Li, and Jin Dou Zhao. "Reverse Analysis for Determining the Stiffness Characteristics of Suspension Spring with Variable Pitch and Wire Diameter." Advanced Materials Research 421 (December 2011): 783–87. http://dx.doi.org/10.4028/www.scientific.net/amr.421.783.
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A reverse analysis method for determining the stiffness characteristics of nonlinear suspension spring with variable pitch and wire diameter is developed by introducing the ideas of dispersion. Meanwhile, the reverse analysis of a nonlinear suspension spring used in truck is completed as an example, and the progressive force-displacement curves obtained by theoretical and experimental analysis are compared in order to verify the validity of the reverse analysis method used for nonlinear suspension spring.
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Adamchuk, V., V. Bulgakov, I. Holovach, and Z. Ruzhylo. "Theoretical studies of oscillations of the cleaning working bodies spiral potato separator." Mehanization and electrification of agricultural, no. 10(109) (2019): 11–22. http://dx.doi.org/10.37204/0131-2189-2019-10-1.
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Purpose. Increase of efficiency of potato tubers cleaning process from impurities of new construction of spiral separator taking into account and activation of vibrating process of its cleaning spiral springs. Methods. The research was carried out with the use of higher mathematics, theoretical mechanics, elasticity theory and methods of programming and numerical calculations with the help of PC. Results. For the developed construction of the spiral separator of potato heap, which consists of cantilever mounted cleaning spiral springs, the mathematical model of free ends of spiral oscillations under the influence of external load is developed. An equivalent bending scheme of the cantilever spiral under the action of uniformly distributed load, selected corresponding axes of coordinates and parameters characterizing the vibrational process of the spiral end are determined. For such an equivalent scheme, a differential equation of cleaning spiral oscillations in partial derivatives is made for the first time. After the corresponding transformations, the differential equation was numerically solved according to the program, by means of a PC. This made it possible to find the dependence of the change in the winding pitch of the cleaning spiral spring as a result of its deformation, in particular, the simultaneous longitudinal stretching and transverse deflection, on its length. Also new analytical dependences of the reduced moment of inertia of the section of the cantilever spring are received, on the basis of which graphic dependences of change of its value on length of a spiral spring at the set diameter, pitch of skills, angle of rise of a coil and angular speed of rotation have been received on the PC. Conclusions 1.The calculated mathematical model of vibrations of the working bodies of the spiral separator of potato heap is constructed, as a result the differential equation of transverse bending vibrations of its console cleaning spiral spring is made. 2.On the basis of the differential equation solution of transverse bending oscillations of the cleaning spiral spring the analytical expressions describing the law of vibrational process and deflection of the spiral spring at any moment of time for any point of its longitudinal axis are received. 3.Analytical dependencies are obtained to determine the variable pitch of a curved coil spring at any given time and for any inter-turn lumen during this oscillatory process. 4.At the angular velocity of the spiral spring, which is equal to ω = 30 rad∙s-1, the density of the material of which the spring is made, = 7700 kg∙m-3, modulus of elasticity Е = 2∙1011 Pa, the radius of the bar = 8.5 mm, uniformly distributed spiral spring load by potato heap intensity 1000 Н∙m-1 the total spring deflection along its length varies from 0 to 0.25 m. 5.The obtained analytical expressions of restriction on the maximum change of the cleaning spiral spring pitch at its fluctuations from the condition that potato tubers do not fall into the spring inter-turn space taking into account structural and kinematic parameters of the cleaning spiral spring, the material from which it is made, technological modes of operation and tubers' sizes. 6.As the numerical calculations on the PC show, a cleaning spiral spring with the above parameters and an initial winding pitch S = 48 mm at the considered transverse oscillations at the expense of deformation can change a step up to 54 mm that will provide not falling out of a potato tuber outside of a separator of a potato heap. Keywords: potatoes, digging, impurities, cantilever spiral spring, oscillations, differential equation, numerical calculations on PC.
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Yigit, Cihat Bora, and Pinar Boyraz. "Design and Modelling of a Cable-Driven Parallel-Series Hybrid Variable Stiffness Joint Mechanism for Robotics." Mechanical Sciences 8, no. 1 (2017): 65–77. http://dx.doi.org/10.5194/ms-8-65-2017.
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Abstract. The robotics, particularly the humanoid research field, needs new mechanisms to meet the criteria enforced by compliance, workspace requirements, motion profile characteristics and variable stiffness using lightweight but robust designs. The mechanism proposed herein is a solution to this problem by a parallel-series hybrid mechanism. The parallel term comes from two cable-driven plates supported by a compression spring in between. Furthermore, there is a two-part concentric shaft, passing through both plates connected by a universal joint. Because of the kinematic constraints of the universal joint, the mechanism can be considered as a serial chain. The mechanism has 4 degrees of freedom (DOF) which are pitch, roll, yaw motions and translational movement in z axis for stiffness adjustment. The kinematic model is obtained to define the workspace. The helical spring is analysed by using Castigliano's Theorem and the behaviour of bending and compression characteristics are presented which are validated by using finite element analysis (FEA). Hence, the dynamic model of the mechanism is derived depending on the spring reaction forces and moments. The motion experiments are performed to validate both kinematic and dynamic models. As a result, the proposed mechanism has a potential use in robotics especially in humanoid robot joints, considering the requirements of this robotic field.
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Zhang, Jian, Zhaohui Qi, Gang Wang, and Shudong Guo. "High-Efficiency Dynamic Modeling of a Helical Spring Element Based on the Geometrically Exact Beam Theory." Shock and Vibration 2020 (June 19, 2020): 1–14. http://dx.doi.org/10.1155/2020/8254606.
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This paper presents a modeling study of the dynamics of a helical spring element with variable pitch and radius considering both the static stiffness and dynamic response by using the geometrically exact beam theory. The geometrically exact beam theory based on the Euler–Bernoulli beam hypothesis is described, of which the shear deformations are ignored. Unlike the traditional spliced curved beam element method, the helical spring element is described with curvature vector and axial strain by establishing and spline-interpolating a function of the radius, the height, the polar angle, and the torsion angle of the whole spring. In addition, a model smoothing method is developed and applied in the numerical analysis to filter the high-frequency oscillation component of the flexible multibody systems, so as to correct the system dynamic equations and improve the calculation efficiency when solving the static equilibrium of the spring. This study also carries out five numerical trials to validate the above dynamic procedure of the helical spring element. The example of the spring static stiffness design shows that the proposed helical spring procedure enables one to deal with practical engineering applications.
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Orlowski, Kazimierz A., Michal Dobrzynski, Grzegorz Gajowiec, Marcin Lackowski, and Tomasz Ochrymiuk. "A Critical Reanalysis of Uncontrollable Washboarding Phenomenon in Metal Band Sawing." Materials 13, no. 20 (2020): 4472. http://dx.doi.org/10.3390/ma13204472.
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The article analyzes the cutting process of hard bars. Investigations conducted in industrial conditions demonstrated the presence of surface errors in the machined workpieces in the form of washboard patterns. The purpose of this study was to analyze the results of cutting on band sawing machines with different band saw blades. The cutting processes were conducted on three different horizontal band sawing machine types. Analyzed material was an alloy steel Ø40 mm rod with a hardened surface covered with a thin layer of chromium. The hardness of the outer layer was 547 HV with a core hardness of 180 HV. The surface topography measurements of the processed workpieces were carried out with the 3D Optical Profiler, which supplied information on the irregularities of the processed material texture. In each of the analyzed cases, a corrugated surface was obtained after sawing, which is the effect of the occurrence of the washboarding phenomenon, despite the fact that the teeth of each band saw had variable pitches. The washboarding phenomenon when cutting rods with hard surfaces is caused by the phenomenon of wave regeneration. Despite the use of variable pitch saw blades, the cutting process results in rippling of the sawn surface, which is caused by the high hardness of the outer layer of the workpiece, as well as by the type of tool with spring setting of teeth.
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Kwon, H. D., and M. Burdekin. "Measurement and diagnostics of machine tool errors during circular contouring motions." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 212, no. 5 (1998): 343–56. http://dx.doi.org/10.1243/0954405981515950.
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This paper deals with the measurement and diagnosis of the machine tool errors by application of the ball link bar system. It includes the development of a new link bar, the in-plane and out-of-plane measurement techniques and the machine error analysis system. The new type of ball link incorporates an idealized three-point kinematic contact principle between the balls and sockets of the link bar, and provides the following features: (a) the minimum length of the link corresponds to the minimum length of a standard LVDT transducer, (b) the link is of light weight, (c) the accuracy and the repeatability of the link corresponds to that of the LVDT (linear variable differential transformer) transducer and (d) the link is mounted between two reference balls by using the spring force of the LVDT transducer and thereby eliminating the need for magnets as in the case of the conventional double-ball bar. With the in-plane and out-of-plane measurements under different test conditions, the machine errors, such as set-up errors, closing errors, backlash errors, dynamic backlash errors, positional errors, pitch motion errors, transient errors around the start point of the test path, vibration due to too high a gain setting, stick-slip errors, squareness errors and servo mis-match errors, can be analysed by the application of the machine error analysis software. Practical measurements on the TAKISAWA CNC (computerized numerical control) machining centre were carried out and the machine tool errors were effectively evaluated.
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Kim, HyungTae, CheolHo Kim, SungBok Kang, KangWon Lee, JaeHo Baek, and HyunHee Han. "A 3 DOF Model for an Electromagnetic Air Mount." Advances in Acoustics and Vibration 2012 (January 18, 2012): 1–6. http://dx.doi.org/10.1155/2012/218429.
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A matrix model with three degrees of freedom is proposed as a means for controlling microvibrations and applied to an electromagnetic isolator. The model was derived from an assumption based on small- and low-frequency vibrations. The coordinates of the 3 DOF was composed of the 4 variables, representing a vertical position, pitch, roll, and a proof term. The coordinates were calculated from the 4 position sensors in the isolator and formulated into a matrix, which possesses inversive full rank. The electro-magnetic isolator was built for a simulated machine in semiconductor manufacturing and consisted of a heavy surface plate, sensors, amps, a controller, and air springs with electromagnets. The electromagnets are installed in a pneumatic chamber of the individual air spring. The performance of the 3 DOF model was experimented and compared with that of a 1 DOF model in an impact test. The settling time in the result was reduced to 25%.
Dissertations / Theses on the topic "Variable pitch spring"
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Qiu, Donghai. "Theoretical and experimental study of tuned nonlinear energy sink : application to passive vibration control." Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0029/document.
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: Les travaux présentés dans cette thèse traitent du contrôle de systèmes dynamiques soumis à des excitations harmoniques et transitoires en utilisant des absorbeurs de type Nonlinear Energy Sink (NES). Plusieurs aspects ont été développés : la conception et la réalisation d'un nouveau design pour le NES cubique, l'étude de la location et du transfert irréversible d'énergie sur un NES bistable et le développement d'un critère de conception pour un NES à Vibro-Impact (VI). Dans un premier temps, un critère de conception est proposé pour le NES à raideur cubique. Le design proposé est basé sur des ressorts coniques ou des ressorts à pas variable. Un mécanisme à raideur négative est aussi introduit pour supprimer la partie linéaire et avoir une raideur cubique pure. Dans un deuxième temps, le concept du NES est validé expérimentalement par des essais statiques et des essais dynamiques. Une analyse de sensibilité est aussi menée sur la longueur des ressorts précontraints, elle dénote parfois un état bistable de l'oscillateur. Ensuite, le NES bistable ainsi obtenu est étudié plus en détail. Ce type d'absorbeur s'avère être très robuste pour différents types d’excitation. Des études expérimentales sont aussi menées afin d'explorer le comportement dynamique. Enfin, un critère de conception est proposé pour le NES à Vibro-Impact. Des calculs analytiques détaillés sont proposés pour contrôler les vibrations sous différentes excitations. L'étude expérimentale montre une bonne cohérence avec les résultats théoriques<br>The work presented in this thesis deals with the passive control of dynamics systems subjected to harmonic and transient excitations using a Nonlinear Energy Sink (NES). Several research aspects have been developed: design theory and experimental study of a novel NES, efficient Targeted Energy Transfer (TET) of bistable NES and design criteria for optimally tuned Vibro-Impact (VI) NES. Firstly, a design criterion intended to provide optimal nonlinear stiffness is proposed. Then a novel design of NES system yielding cubic stiffness with conical springs or variable pitch springs and negative stiffness mechanism is developed. Secondly, the experimental procedures for static and dynamic test are presented and applied to validate the concept of NES system. Then a sensitivity analysis is performed with respect to the pre-compressed length of springs. Thirdly, the optimal design of the above device with negative stiffness (termed as bistable NES) is studied. This type of NES is proved to work robustly for different types of excitation, and experimental study of semi-active control are explored. Finally, design criteria for optimally tuned VI NES are studied. Detailed analytical calculations of clearance to control the vibration under different excitations are proposed. A good correspondence between theoretical and experimental results is observed
Book chapters on the topic "Variable pitch spring"
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Wu, Zhenhang, Manuel Paredes, and Sébastien Seguy. "Constraint Analysis and Optimization of NES System Based on Variable Pitch Spring." In Lecture Notes in Mechanical Engineering. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_26.
Full textAbstract:
AbstractThis study proposes the realization of a device with a pure cubic stiffness mechanism to suppress a wide range of vibrations, which is known as the Nonlinear Energy Sink. Deciding how to construct a light, reliable NES device is always a challenge. According to our design, the device can counterbalance the undesirable linear stiffness that emerges from the intrinsic property of a variable pitch spring. Our goal is to reduce the mass of the spring while keeping the same cubic stiffness. Through the multifaceted analysis of the nonlinear constraint, we try to explore the full potential of NES device to reduce its mass. Meanwhile, a global search method, Multi Start, is applied by repeatedly running a local solver. Finally, a new design with different variable pitch distribution is proposed.
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Yau, Henry, and Richard W. Longman. "Modeling of Non-ideal Variable Pitch Valve Springs for Use in Automotive Cam Optimization." In Modeling, Simulation and Optimization of Complex Processes. Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25707-0_27.
Full textConference papers on the topic "Variable pitch spring"
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Mohammed, Riyaz, and Hong Zhou. "Synthesis of Variable-Diameter Helical Extension Springs." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66096.
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Helical extension springs store energy and provide resistance to tensile loads that are applied through appropriate spring ends. Typical spring ends include different types of hooks or loops. Both ends of a helical extension spring are attached to other components. When the two components move apart and their distance is increased, the helical extension spring exerts a tensile force between the two components and tries to decrease their distance. There are various applications for helical extension springs that include automobiles, toys, hand tools, agriculture machines, textile machines, and medical devices. The common configuration of helical extension springs uses straight cylindrical shape that has constant coil diameter and pitch. Unlike regular helical extension springs, variable-diameter helical extension springs do not employ constant coil diameter. Their variable coil diameter enables them to produce desired force deformation relationships and reduce stress concentration. The distinctive features of variable-diameter helical extension springs also raise their synthesis challenges. To surmount these challenges, a method is introduced in this paper to model and design variable-diameter helical extension springs. The configuration of a synthesized spring is described by a composite parametric curve. The entire spring is defined by its control parameters. Synthesizing the spring is systematized as optimizing its control parameters. Examples on modeling, analyzing and designing springs are presented in the paper to demonstrate the procedure and verify the effectiveness of the introduced synthesis method.
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Sun, Ke, Jian-hua Zhang, Liang Zhang, and Wei Shao. "The Influence of Spring Stiffness for a Passive Variable-Pitch Tidal Current Turbine." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23953.
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In this present work, a kind of passive variable-pitch tidal current turbine named spring-control turbine is studied by computational fluid dynamics (CFD) numerical simulation. FLUENT is applied combined with its second developing custom interface-User Define Function (UDF), where torque balanced equation of blade are connected into the fluid conservation equation solver. The variable pitch angle of a single blade of a test model is used as the validation of the numerical model. Considering the variable rules of the torque and power with the pitch angle of a single blade, we find that the bigger spring stiffness is more benefit for energy extraction of a tidal current turbine.
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Gandham, Naresh Kumar, and Hong Zhou. "Synthesis of Concave Helical Compression Springs." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50800.
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Helical compression springs are used to resist compressive forces or store energy in push mode. They are found in many applications that include automotive, aerospace and medical devices. The common configuration of helical compression springs is straight cylindrical shape that has constant coil diameter, constant pitch and constant spring rate. Unlike cylindrical helical compression springs, concave helical compression springs have a larger diameter at each end and a smaller diameter in the middle of the spring. The variable coil diameter enables them to produce desired load deflection characteristics, reduce solid height, buckling and surging, and keep them centered on a larger diameter hole. The unique features of concave helical compression springs also raise their synthesis challenges. In this paper, a method is introduced to synthesize concave helical compression springs. The variable coil diameter of a concave helical compression spring is described by a spline curve. A cylinder with variable diameter is generated by revolving the spline curve on spring axis. The concave helical compression spring is then modeled by wrapping a spring wire on the variable diameter cylinder. The synthesis of a concave helical compression spring is systemized as the optimization of the geometric control parameters of its wrapped spring wire. A synthesis example is presented in the paper to verify the effectiveness and demonstrate the procedure of the introduced method.
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Yau, Henry, and Richard W. Longman. "Investigation of the Potential for Reducing Energy Usage in Cam Follower Systems by Means of Variable Pitch Springs." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63214.
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Although the spring is an integral component of most any cam follower system, its design is often ignored in studies aimed at minimizing energy loss. This study makes an initial assessment of the possible energy savings that can be achieved by using a spring designed with a variable pitch. Using a simple spring model that accounts for coil contacts, the pitch is optimized in numerical experiments and the energy savings are calculated. The experiments show that savings in energy are promising enough to warrant further investigation.
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Wakeham, Keith J., and D. Geoff Rideout. "Model Complexity Requirements in Design of Half Car Active Suspension Controllers." In ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASMEDC, 2011. http://dx.doi.org/10.1115/dscc2011-5955.
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This paper investigates the appropriate level of model complexity when designing optimal vehicle active suspension controllers using the Linear Quadratic Regulator (LQR) method. The LQR method requires the formulation of a performance index with weighting factors to penalize the three competing objectives in suspension design: suspension travel (rattle space), sprung mass acceleration (ride quality) and tire deflection (road-holding). The optimal control gains are determined from the solution of a matrix Riccati equation with dimension equal to the number of state variables in the model. A quarter car model with four states thus poses a far less onerous formulation problem than a half or full car model with eight or more states. However, half and full car models are often assumed to be more accurate than quarter car models, and necessary for capturing and controlling degrees of freedom such as pitch and roll motion which are not directly available from a quarter car. The vertical acceleration, pitch acceleration and roadholding of a pitch plane vehicle are controlled in this paper using both quarter and half car-based controllers. First, optimal gains are calculated for each of the front and rear actuators assuming that the front and rear of the vehicle can be separately modeled as quarter cars with four states each. Then, half car-based optimal gains, based on feedback of eight states for the entire vehicle, are computed. Using quarter car-based controllers at the front and rear of a half car gives superior performance in reducing sprung mass inertial acceleration, and can effectively control pitch motion even when interactions between front and rear suspensions are not decoupled. Minimizing vertical motion of the front and rear ends indirectly regulates pitch motion. Improvements resulting from the additional complexity of the half car-based controller are seen only when the weighting factor for pitch suppression is very high in the performance index.
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Sperry, Brian, Corina Sandu, and Brent Ballew. "Complex Bogie Modeling Incorporating Advanced Friction Wedge Components." In 2009 Joint Rail Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/jrc2009-63037.
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This research focuses on the dynamic behavior of the three-piece bogie that supports the freight train car bodies. While the system is relatively simple, in that there are very few parts involved, the behavior of the bogie is somewhat more complex. Our research focuses primarily on the behavior of the friction wedges under different operating conditions that are seen under normal operation. The Railway Technologies Laboratory (RTL) at Virginia Tech has been developing a model to better capture the dynamic behavior of friction wedges using 3-D modeling software. In previous years, a quarter-truck model, and half-truck variably damped model have been developed using MathWorks MATLAB®. This year, research has focused on the development of a half-truck variably damped model with a new (curved surface) friction wedge, and a half-truck constantly damped model, both using the MATLAB® based software program. Currently a full-truck variably damped model has been created using LMS Virtual.Lab. This software allows for a model that is more easily created and modified, as well as allowing for a much shorter simulation time, which became a necessity as more contact points, and more complex inputs were needed to increase the accuracy of the simulation results. The new model consists of seven rigid bodies: the bolster, two sideframes, and four wedges. We have also implemented full spring nests on each sideframe, where in previous models equivalent spring forces were used. The model allows six degrees-of-freedom for the wedges and bolster: lateral, longitudinal, and vertical translations, as well as pitch, roll, and yaw. The sideframes are constrained to two degrees-of-freedom: vertical and longitudinal translations. The inputs to the model are vertical and longitudinal translations or forces on the sideframes, which can be set completely independent of each other. The model simulation results have been compared with results from NUCARS®, an industrially-used train modeling software developed by the Transportation Technology Center, Inc. (TTCI), a wholly owned subsidiary of the Association of American Railroads (AAR), for similar inputs, as well as experimental data from warping tests performed at TTCI.
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Rosenberger, G. Walter, Peter E. Klauser, George P. Binns, and Gary P. Wolf. "Using Parametric Simulation to Optimize Suspension Design." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-55257.
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A project to design and implement suspension improvements to Amtrak’s F-40 Non-Powered Control Unit (NPCU) cars is described. The cars, built from former F-40 locomotives, had a history of poor ride quality. Rail Sciences Inc. (RSI) inspected one of the cab cars and measured its ride quality. Peter Klauser modeled the vehicle in NUCARS™ and validated the model against the test data. The vehicle response was primarily in pitch and bounce modes. To optimize the suspension, Klauser simulated vehicle response for a range of four suspension parameters: primary stiffness and damping, and secondary stiffness and damping. Nearly 2600 suspension combinations were considered. Simulation file setup and data analysis were performed automatically using parameter analysis software interacting with NUCARS™. The result was a five-dimensional response contour for each output variable, such as the engineer’s seat vertical and lateral accelerations, and car body acceleration. The most cost effective stiffness and damping parameters were selected from the response contour and translated into component specifications. RSI then provided Amtrak with new axle box springs and dampers, and re-tested the vehicle. The test result closely followed the predicted results from the simulation. Engineer’s seat vertical and cab lateral accelerations improved by 42% and 32% respectively for the worst-case conditions in the test territory.