Academic literature on the topic 'Enhanced FEM stability simulations'
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Journal articles on the topic "Enhanced FEM stability simulations"
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Zhang, Yanan, Peigang Jiao, Weibo Du, Guoqing Qi, and Bowen Chen. "Numerical Simulation of Casting Filling Process Based on SPH-FEM Coupling Method." Symmetry 17, no. 4 (2025): 494. https://doi.org/10.3390/sym17040494.
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The coordinated optimization of free-surface dynamics tracking and solid deformation computation remains a persistent challenge in casting filling simulations. While the traditional smoothed particle hydrodynamics (SPH) method suffers from prohibitive computational costs limiting practical applications, the delayed interface updates of the finite element method (FEM) compromise simulation fidelity. This study proposes a symmetric SPH-FEM coupling algorithm that integrates real-time particle-grid data exchange, and validation through ring filling simulations demonstrated close agreement with Schmid’s benchmark experiments, confirming flow field reconstruction reliability. Furthermore, bottom-injection plate experiments verified the method’s thermal modeling stability, achieving fully coupled flow–thermal–stress simulations with enhanced computational efficiency. The proposed symmetric coupling framework achieves engineering-ready simulation speeds without compromising accuracy, and this advancement establishes a novel computational tool for predicting casting defects including porosity and hot tears, significantly advancing the implementation of high-fidelity numerical simulation in foundry engineering applications.
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Zheng, Zumei, Shasha Zhou, Jun Chen, Naoto Mitsume, and Shunhua Chen. "A Multi-Resolution MPS/FEM Coupling Method for Three-Dimensional Fluid–Structure Interaction Analysis." Journal of Marine Science and Engineering 11, no. 8 (2023): 1483. http://dx.doi.org/10.3390/jmse11081483.
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This work aims to propose an efficient MPS/FEM coupling method for the simulation of fluid–structure interaction (FSI), where the MPS and FEM are respectively employed to account for fluid flows and structural deformation. The main idea of our method is to develop a multi-scale multi-resolution MPS method for efficient fluid simulations in the context of MPS/FEM coupling. In the developed multi-scale MPS method, the fluid domain is discretized into particles of different resolutions before calculation, where particles close to the interest domain will be discretized into high resolution, while the rest are discretized into low resolution. A large particle interacting with small particles is divided into several small particles virtually, and weight functions are redefined to maintain the simulation stability. A bucket-sort-based algorithm is developed for the fast search of multi-resolution neighboring particles. The capacity of a newly proposed ghost cell boundary model is further enhanced, so as to accurately treat wall boundary problems with particles of different resolutions. On this basis, the multi-resolution MPS method is coupled with the FEM for FSI simulations. Finally, several numerical examples are conducted to demonstrate the accuracy and efficiency of the development method.
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Demin, Vladimir, Alexey Kalinin, Nadezhda Tomilova, et al. "Advanced Digital Modeling of Stress–Strain Behavior in Rock Masses to Ensure Stability of Underground Mine Workings." Civil Engineering Journal 11, no. 3 (2025): 1072–87. https://doi.org/10.28991/cej-2025-011-03-014.
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This study focuses on optimizing underground support systems through advanced numerical modeling and geomechanical assessment. The research aims to refine reinforcement parameters for underground mine workings by analyzing the stress-strain behavior of rock masses using Rocscience RS2 software. The study integrates geological and geotechnical data, including field observations and numerical simulations, to enhance the accuracy of support system designs. The methodology is based on the finite element method (FEM) and the Hoek–Brown softening model, allowing the identification of plastic deformation zones and stress redistribution patterns. The results confirm that maximum stress increases by 35–40% for every 100 m of depth, necessitating enhanced reinforcement. The study evaluates hybrid support systems, specifically steel-polymer bolts with shotcrete, demonstrating a 15% reduction in plastic deformations compared to conventional methods. The findings highlight the importance of continuous geotechnical monitoring and adaptive reinforcement strategies to ensure stability in highly fractured rock masses. The proposed approach provides a more precise prediction of excavation stability, contributing to the development of safer and more efficient underground mining practices. Future research may include the integration of intelligent monitoring systems equipped with real-time sensors to further optimize support strategies and long-term stability assessments. Doi: 10.28991/CEJ-2025-011-03-014 Full Text: PDF
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Song, Eun Jeong, Jung Soo Lee, Hyungpil Moon, Hyouk Ryeol Choi, and Ja Choon Koo. "A Multi-Curvature, Variable Stiffness Soft Gripper for Enhanced Grasping Operations." Actuators 10, no. 12 (2021): 316. http://dx.doi.org/10.3390/act10120316.
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For soft grippers to be applied in atypical industrial environments, they must conform to an object’s exterior shape and momentarily change their stiffness. However, many of the existing grippers have limitations with respect to these functions: they grasp an object with only a single curvature and a fixed stiffness. Consequently, those constraints limit the stability of grasping and the applications. This paper introduces a new multicurvature, variable-stiffness soft gripper. Inspired by the human phalanx and combining the phalanx structure and particle jamming, this work guarantees the required grasping functions. Unlike the existing soft pneumatic grippers with one curvature and one stiffness, this work tries to divide the pressurized actuating region into three parts to generate multiple curvatures for a gripper finger, enabling the gripper to increase its degrees of freedom. Furthermore, to prevent stiffness loss at an unpressurized segment, this work combines divided actuation and the variable-stiffness capability, which guarantee successful grasping actions. In summary, this gripper generates multiple grasping curvatures with the proper stiffness, enhancing its dexterity. This work introduces the new soft gripper’s design, analytical modeling, and fabrication method and verifies the analytic model by comparing it with FEM simulations and experimental results.
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Wei, Wei, Songjian Yu, and Baozuo Li. "Research on Magnetic Characteristics and Fuzzy PID Control of Electromagnetic Suspension." Actuators 12, no. 5 (2023): 203. http://dx.doi.org/10.3390/act12050203.
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This paper proposes an electromagnetic suspension with an electromagnetic actuator, which can improve the riding comfort and stability of the vehicle without changing the safety of traditional MacPherson suspension. First, the electromagnetic suspension structure is introduced, and the principle of the proposed actuator is described in detail. Second, a magnetic flux density model of a single PM ring (permanent magnetic ring) and a magnet assembly are built, and a theoretical analysis of the magnetic flux density is carried out for comparison. Then, the magnetic flux distribution of the magnetic field is simulated and analyzed using the finite element method (FEM), and is compared with theoretical and other experimental data. Finally, a vehicle dynamics model with 7 DOF is built, and vehicle simulations based on the fuzzy PID algorithm are carried out on a C-grade road surface and a deceleration strip. The theoretical results and simulation analyses of the FEM indicate that compared with the MacPherson suspension, the root mean square values of the acceleration of centroid acceleration for the electromagnetic suspension are increased by 59.08% and 33.34%, respectively, on a C-grade road surface and a deceleration strip, and other physical quantities have also been improved. The structure and characteristics of the proposed electromagnetic suspension that improve the riding comfort of the suspension and enhance the stability of the MacPherson suspension are feasible.
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Primo, Gustavo S. P., Ramon Silva, Francisco Evangelista, and Marcos H. Oliveira. "Statistical Reliability Analysis for Assessing Bridge Structural Integrity: A Review Paper." Infrastructures 10, no. 7 (2025): 156. https://doi.org/10.3390/infrastructures10070156.
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This article reviews methods for estimating the remaining service life of bridges, focusing on the statistical analysis of reliability indices, which aids in identifying risks and predicting structural failures. Among the methodologies examined, the First-Order Reliability Method (FORM) is highlighted for its effectiveness in calculating failure probabilities based on current deterioration and loading conditions. Sensitivity analysis is also discussed, as it pinpoints the variables that most significantly impact structural stability. Enhanced using the Finite Element Method (FEM), this method allows the simulation of structural behavior across different deterioration scenarios, improving the precision of failure predictions and optimizing maintenance planning. This review provides insight into how the integration of probabilistic methods and sensitivity analysis can enhance failure prediction and support more efficient maintenance planning for bridge structures.
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Kien, Dang Van, Do Ngoc Anh, and Do Ngoc Thai. "Numerical Simulation of the Stability of Rock Mass around Large Underground Cavern." Civil Engineering Journal 8, no. 1 (2022): 81–91. http://dx.doi.org/10.28991/cej-2022-08-01-06.
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Geotechnical problems are complicated to the extent and cannot be expected in other areas since non-uniformities of existing discontinuous, pores in materials and various properties of the components. At present, it is extremely difficult to develop a program for tunnel analysis that considers all complicated factors. However, tunnel analysis has made remarkable growth for the past several years due to the development of numerical analysis method and computer development, given the situation that it was difficult to solve formula of elasticity, viscoelasticity, and plasticity for the dynamic feature of the ground when the constituent laws, yielding conditions of ground materials, geometrical shape and boundary conditions of the structure were simulated in the past. The stability of rock mass around an underground large cavern is the key to the construction of large-scale underground projects. In this paper, the stability analysis was carried out based on those parameters by using 2D FEM RS2 program. The calculated stress and displacements of surrounding rock and rock support by FEM analysis were compared with those allowable values. The pattern of deformation, stress state, and the distribution of plastic areas are analyzed. Finally, the whole stability of surrounding rock mass of underground caverns was evaluated by Rock Science - RS2 software. The calculated axial forces were far below design capacity of rock bolts. The strong rock mass strength and high horizontal to vertical stress ratio enhanced safe working conditions throughout the excavation period. Thus wide span caverns and the system of caverns could be stability excavated sedimentary rock during the underground cavern and the system of caverns excavation by blasting method. The new method provides a reliable way to analyze the stability of the caverns and the system of caverns and also will help to design or optimize the subsequent support. Doi: 10.28991/CEJ-2022-08-01-06 Full Text: PDF
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Msolli, Sabeur. "Shear Instability and Localization in High-Speed Cold Spray Processes: Impact on Particle Fragmentation and Bonding Mechanisms." Materials 18, no. 3 (2025): 490. https://doi.org/10.3390/ma18030490.
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This study investigates the deformation behavior and interfacial phenomena occurring during the high-velocity impact of a copper particle into a copper substrate under various conditions using FEM. It also offers an enhanced physics-based model based on discrete dislocation dynamics simulations to depict newly observed features such as interfacial instabilities and shear localization leading to bonding and particle fragmentation. To investigate bonding mechanisms at the particle–substrate interface, additional simulations using a one-element-thickness model are conducted. These simulations focus on the deformation behavior at the interface, revealing wavy shape formation in the substrate due to disparities in strain-rate levels. Material instabilities, localized at the intersection of plane and release waves, progress hand-in-hand during the early stages of impact, suggesting shear behavior as a precursor to instabilities. The effect of shear viscosity on particle deformation and interfacial behavior is also examined, showing that increased viscosity leads to thermal material softening and enhanced deformation. Material jetting and interfacial instability are observed, particularly at higher viscosity thresholds. Additionally, the impact of drag coefficient variations on particle deformation is explored, indicating a critical role in interfacial stability and particle flattening. Finally, the occurrence of adiabatic shear instability and localization is investigated, revealing shear localization regions at the particle–substrate interface and within the particle itself responsible for particle fragmentation. To this aim, damage initiation and evolution laws are applied to identify regions of shear localization, crucial for particle–substrate bonding and mechanical interlocking. The impact velocity is shown to influence shear localization, with higher velocities resulting in increased deformation and larger localization regions.
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Xiao, Enzhao, Shengquan Li, Ali Matin Nazar, Ronghua Zhu, and Yihe Wang. "Antarctic Snow Failure Mechanics: Analysis, Simulations, and Applications." Materials 17, no. 7 (2024): 1490. http://dx.doi.org/10.3390/ma17071490.
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Snow failure is the process by which the stability of snow or snow-covered slopes is destroyed, resulting in the collapse or release of snow. Heavy snowfall, low temperatures, and volatile weather typically cause consequences in Antarctica, which can occur at different scales, from small, localized collapses to massive avalanches, and result in significant risk to human activities and infrastructures. Understanding snow damage is critical to assessing potential hazards associated with snow-covered terrain and implementing effective risk mitigation strategies. This review discusses the theoretical models and numerical simulation methods commonly used in Antarctic snow failure research. We focus on the various theoretical models proposed in the literature, including the fiber bundle model (FBM), discrete element model (DEM), cellular automata (CA) model, and continuous cavity-expansion penetration (CCEP) model. In addition, we overview some methods to acquire the three-dimensional solid models and the related advantages and disadvantages. Then, we discuss some critical numerical techniques used to simulate the snow failure process, such as the finite element method (FEM) and three-dimensional (3D) material point method (MPM), highlighting their features in capturing the complex behavior of snow failure. Eventually, different case studies and the experimental validation of these models and simulation methods in the context of Antarctic snow failure are presented, as well as the application of snow failure research to facility construction. This review provides a comprehensive analysis of snow properties, essential numerical simulation methods, and related applications to enhance our understanding of Antarctic snow failure, which offer valuable resources for designing and managing potential infrastructure in Antarctica.
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Chen, Peng, Xiaorong Cai, Na Min, et al. "Enhanced Fatigue Resistance of Nanocrystalline Ni50.8Ti49.2 Wires by Mechanical Training." Metals 13, no. 2 (2023): 361. http://dx.doi.org/10.3390/met13020361.
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In this paper, the fatigue resistance of superelastic NiTi shape memory alloy (SMA) wires was improved by combining mechanical training and nanocrystallization. Fatigue tests were performed after mechanical training with a peak stress of 600 MPa for 60 cycles of nanocrystalline (NC) NiTi wires, and the associated microscopic mechanism was investigated by using transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD). The results showed that stress-controlled training effectively improved the functional stability (the accumulated residual strain decreased by 83.8% in the first 5000 cycles) of NC NiTi SMA wires, as well as increased the average structural fatigue life by 187.4% (from 4538 cycles to 13,040 cycles). TEM observations and TKD results revealed that training-induced dislocations resulted in lattice rotation and preferential grain orientation. The finite element method (FEM) simulation results indicated that the training-induced preferential grain orientation tended to decrease the local stress concentration and strain energy density. Combined with fractography analysis, the uniform deformation caused by mechanical training changed the crack growth mode from multi-regional propagation to single-regional propagation, improving the structural fatigue life.
Dissertations / Theses on the topic "Enhanced FEM stability simulations"
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Strubel, Nicolas. "Brake squeal : identification and influence of frictional contact localizations." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN059.
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En tant que radiations acoustiques intenses impliquant de conséquentes nuisances environnementales ainsi que de nombreux retours clients, le crissement des systèmes de freinage est un problème de vibration induite par frottement dépendant indubitablement de problématiques multi-physiques et multi-échelles. Parmi ces dernières, la structure du système, les paramètres opérationnels de freinage, les interfaces de contact frottant, couplés à une dépendance en température, ainsi que les non-linéarités de contact ou les aspects tribologiques, sont des éléments affectant considérablement le crissement, faisant de ce déplaisant bruit un sujet complexe à appréhender. Au sein de ce travail, le système complet de freinage est considéré, et plusieurs tendances principales sont identifiées au regard de l'influence des localisations de contact sur les émissions acoustiques.Des essais NVH sont réalisés, cette analyse implique différentes échelles d'intérêt visant à changer les caractéristiques de contact : les plaquettes de freinage sont modifiées d'une part à l'échelle macroscopique -avec la volonté de varier implicitement les zones de portance-, d'autre part à l'échelle mésoscopique -tendant à impacter l'évolution du circuit tribologique-. Le but inhérent est d'identifier les paramètres patins influençant le crissement, en affectant l'interface tribologique et engageant des différences de signatures acoustiques entre les expériences conduites.Des tests fortement instrumentés sont réalisés à l'échelle du système de frein complet, se focalisant sur différentes formes patins : le développement d'une instrumentation enrichie au travers d'un suivi in-operando des surfaces de contact via mesures thermiques, autorise l'accès à des informations de sollicitation supplémentaires, permettant le suivi des zones de portance supposées. L'emploi de méthodes de clustering est considéré afin d'analyser les données thermiques.Des simulations en stabilité impliquant corrélations expérimental / numérique sont effectuées. Des analyses sous-jacentes sont réalisées, en investiguant l'impact de caractéristiques de chanfreins sur le crissement, l'influence du coefficient de frottement, ou l'implémentation de formes globales d'usures. Qui plus-est, les simulations thermomécaniques sont ici d'intérêt, et l'introduction des zones de contact issues des méthodes de clustering est discutée.Bien que la considération du frein complet puisse impliquer de sévères dispersions expérimentales, des corrélations initiales entre les patins modifiés à différentes échelles -via des formes de patins à l'échelle macroscopique et des traitements thermiques à l'échelle mésoscopique- et les caractéristiques de bruit sont observées. Les essais avec instrumentation enrichie concluent que les localisations de contact peuvent varier pendant les tests NVH, dépendant des paramètres de sollicitation. Un lien particulier entre les conditions opérationnelles de freinage (pression, température), les localisations de contact, et le crissement est établi au travers des méthodes de clustering. Également, les tendances observées en simulation tendent à suivre celles expérimentales, et l'enrichissement des modèles via une description plus précise du contact peut présenter des améliorations quant à la capacité de prédiction du crissement de telles simulations<br>As intense acoustic radiations implying consequent environmental nuisances and customer complaints, squeal noises in brake systems are friction-induced vibration issues indubitably depending on multiphysics and multiscales problematics. Among these latter, system structure, braking operational parameters, frictional contact interfaces, coupled to temperature dependency, as well as contact non-linearities or tribological aspects, are elements considerably affecting squeal, making from this unpleasant noise a complex problem to apprehend. In this work, the full scale system is considered, and several principal tendencies are identified regarding the influence of contact localizations on acoustic emissions.NVH tests are conducted, this analysis involves several scales of interest aiming at changing contact characteristics: pads are modified either at the macroscopic scale -with the will of implicitly varying load bearing areas-, or at the mesoscopic one -tending to impact evolution of the tribological circuit-. The inherent purpose is to identify pads parameters influencing squeal, by affecting tribolayer as well as engaging noise signature differences between conducted experiments.Heavily instrumented tests are realized on a full scale brake system, focusing on different pad shapes: the development of an enriched instrumentation through in-operando thermal surface tracking allows to access to supplementary solicitation informations, permitting to follow the assumed load bearing area. The employment of clustering methods is considered to manage the analysis of thermal datas.Experimental / numerical correlated stability simulations are conducted. Subsequent analyses are realized, by investigating pads chamfer characteristic impact on squeal, influence of coefficient of friction, or implementation of global pads wear shapes. Furthermore, thermomechanical simulations are of interest, and the introduction of previously clustered-defined contact areas into models is realized.Although the full brake system consideration can involve severe experimental dispersions, initial correlations between modified pads at different scales -via pad shapes for the macroscopic one, and thermal treatments of friction material focusing on the mesoscopic level- and noise characteristics are observed. Enriched instrumented tests lead to the conclusion that contact localizations can evolve during NVH tests, depending on solicitation variables. A particular link between braking operational parameters (pressure, temperature), contact localizations, and squeal features is established through clustering. Finally, observed simulated tendencies tend to follow experimental ones, and model enrichment via a more accurate contact description could present improvements regarding squeal prediction capability of such simulation
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Griffiths, Thomas Richard. "An Enhanced Data Model and Tools for Analysis and Visualization of Levee Simulations." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3477.pdf.
Full textBook chapters on the topic "Enhanced FEM stability simulations"
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Feil, Jan-Henning, Reimund P. Rötter, Sara Yazdan Bakhsh, et al. "Potential of Improved Technologies to Enhance Land Management Practices of Small-Scale Farmers in Limpopo Province, South Africa." In Sustainability of Southern African Ecosystems under Global Change. Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-10948-5_23.
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AbstractIn this chapter, we explore how, in the face of increasing climatic risks and resource limitations, improved agro-technologies can support sustainable intensification (SI) in small-scale farming systems in Limpopo province, South Africa. Limpopo exhibits high agro-ecological diversity and, at the same time, is one of the regions with the highest degree of poverty and food insecurity in South Africa. In this setting, we analyze the effects of different technology changes on both food security dimensions (i.e., supply, stability, and access) and quality of ecosystem service provision. This is conducted by applying a mixed-method approach combining small-scale farmer survey data, on-farm agronomic sampling, crop growth simulations, and socioeconomic modeling. Results for a few simple technology changes show that both food security and ecosystem service provision can be considerably improved when combining specific technologies in a proper way. Furthermore, such new “technology packages” tailored to local conditions are economically beneficial at farm level as compared to the status quo. One example is the combination of judicious fertilizer application with deficit or full irrigation in small-scale maize-based farming systems. Provided comparable conditions, the results could be also beneficial for decision-makers in other southern African countries.
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Vela Palaquibay, Kevin Joel, Manuel Darío Jaramillo, and Diego Carrión. "Enhanced Reactive Power Compensation for Flicker Mitigation in Wind Farm-Integrated Distribution Networks Using Advanced D-STATCOM Control." In Lecture Notes in Networks and Systems. Springer Nature Switzerland, 2025. https://doi.org/10.1007/978-3-031-87065-1_22.
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Abstract This research aims to demonstrate the importance of reactive power compensation in electrical systems for mitigating fast Flicker voltage disturbances that commonly occur in systems with wind generation; thereby, this paper’s main goal is to improve the quality of distribution systems. The 34-node IEEE test system was chosen as the base system for this study. Simulations were conducted using MATLAB to verify system stability and ensure the system’s nominal voltage matches the design specifications set by the IEEE. The analysis identified bus 27 as having the greatest voltage fluctuation throughout the system. Case studies were conducted on this bus, including the connection of dynamic load and a wind farm (WF) from the MATLAB library, which consists of six 1.5 MW turbines. The Flickermeter in MATLAB, modeled according to IEC-61000 for measuring the short-term Flicker severity index (Pst), was used to evaluate the increase in Pst caused by WF and dynamic loading. To mitigate the flicker severity index, a D-STATCOM of +/−3MVAR based on PID control was implemented. This device was connected to the 34-node IEEE system to reduce the voltage variations produced by both loads.
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Abdul Moiz Hashmi, Syed, Waqar Hussain, Hina Moiz, and Muhammad Hammad Rasool. "Engineering Synthetic Zeolites for Enhanced CO₂ Capture: Strategies, Synthesis, and Applications." In Exploring the World of Zeolites [Working Title]. IntechOpen, 2025. https://doi.org/10.5772/intechopen.1010023.
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Synthetic zeolites offer a promising solution for CO2 capture due to their tunable pore structures, high stability, and selective adsorption properties. This chapter explores advanced synthesis techniques, including hydrothermal, solvothermal, and microwave-assisted methods, alongside post-synthetic modifications such as ion exchange and amine functionalization to enhance CO2 uptake and selectivity. Computational modeling using Density Functional Theory (DFT) and Grand Canonical Monte Carlo (GCMC) simulations provides molecular-level insights, guiding the optimization of adsorption performance. While zeolites demonstrate strong CO2 affinity, challenges like moisture sensitivity, regeneration energy, and scalability remain barriers to industrial adoption. Case studies highlight their potential in flue gas treatment and direct air capture, emphasizing the need for improved material stability and integration with hybrid systems. Advancing zeolite design through interdisciplinary research and sustainable process development is key to unlocking their full potential in large-scale carbon capture applications.
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Bui H.H., Sako K., and Fukagawa R. "Slope stability analysis and slope failure simulation by SPH." In Proceedings of the 17th International Conference on Soil Mechanics and Geotechnical Engineering. IOS Press, 2009. https://doi.org/10.3233/978-1-60750-031-5-1578.
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In this paper, the SPH method is applied to evaluate stability of a slope and to simulate the gross discontinuities after failure. Herein, the Drucker-Prager model with non-associated plastic flow rule is employed to describe the elasto-plastic soil behaviour. The shear strength reduction method is applied to estimate the safety factor of a slope, while critical slip surface is automatically determined from contour plot of accumulated plastic strain. To take into account the pore-water pressure, a new SPH momentum equation is proposed. It is shown that by using this new expression of momentum equation, the free-surface boundary condition between water and submerged soil is automatically imposed without explicitly implementing a computational procedure to calculate an external force (pressure force). This paper suggests that the new SPH momentum equation developed herein is also applicable for further developments of SPH for saturated/unsaturated soils. As an application of the proposed method, slope stability analyses and slope failure simulations of a two-side earth embankment are performed and then comparing with traditional solutions. Very good agreements with limit equilibrium method and finite element method (FEM) have been obtained. This suggests that SPH is a promising method for the current application, especially for handling large deformation and failure of a slope subjected to heavy rainfall or earthquake loading.
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T, Yuvapriya, and Lakshmi P. "Active Suspension Control of Full Car Model Using Bat Optimized PID Controller." In Artificial Intelligence Applications in Battery Management Systems and Routing Problems in Electric Vehicles. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-6631-5.ch008.
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Long drives on bumpy roads and configuration issues like discomfort in seating arrangements have a harmful impact on the human body. The passengers experience severe health problems and stress-related issues. The full car model (FCM) with seven degrees of freedom (DOF) is considered for vibration control analysis. The aim of this work is to optimize the parameters of proportional integral and derivative (PID) controller by grey wolf optimization (GWO) and bat algorithm for betterment in the ride comfort of the passengers. A comparative analysis between the most commonly used PID controller and proposed optimized PID controller was executed over bump input (BI), ISO standard random input (RI), and sinusoidal input (SI) road profiles in MATLAB. Simulation results demonstrate that bat tuned PID (Bat-PID) controller enhances the ride comfort by decreasing the root mean square (RMS), frequency weighted RMS (FWRMS), and vibration dose values (VDV) of the body acceleration (BA) of the vehicle passing over BI, RI, and SI road profiles, which ensures the stability of the vehicle.
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Hassani, Hamid, Anass Mansouri, and Ali Ahaitouf. "Design and Application of a Robust Control System of an Autonomous Multi-Rotor Aircraft Using a Perturbation Estimator." In Advances in Transdisciplinary Engineering. IOS Press, 2024. https://doi.org/10.3233/atde241234.
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In this study, a robust finite-time (FnT) sliding mode attitude and position control is proposed for the precise tracking of an underactuated quadrotor unmanned aerial vehicle (QUAV) subjected to multiple sources of uncertainties, i.e., unmodeled dynamics, external perturbations, and parameter uncertainties. The proposed flight control system is based on the nonsingular integral terminal sliding control (NITSMC) to ensure rapid tracking of the targeted 3D trajectories while reducing the steady state-errors. The performances of the control system are enhanced through the introduction of a disturbance observer (DO) that estimates unknown external disturbances and enhances the system’s robustness. Stability analysis and FnT convergence are verified using the Lyapunov stability analysis. Finally, comparative simulations under different flight conditions are performed to assess the accuracy and robustness of the suggested controller. The obtained results highlight the improved performance of the suggested approach in terms of accuracy, rapidity, and robustness against wind disturbances.
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Kundu, Sombir, Nitin Sundriyal, Navdeep Singh, Sunil Kadiyan, Surender Singh, and Juan M. Ramirez. "Control Strategy for a Single-Phase Grid-Connected PV System With Bidirectional EV Charging Support." In Modern Computing Technologies for EV Efficiency and Sustainable Energy Integration. IGI Global, 2025. https://doi.org/10.4018/979-8-3373-2382-4.ch007.
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The current chapter presents a novel modified complex coefficient filter-based phase-locked loop (MCCF-PLL) control technique for managing a single-phase grid-linked photovoltaic (PV) system integrated with an electric vehicle (EV) charging station. Designed for residential applications, this system enables efficient bi-directional power transfer, supports grid stability, and increases renewable energy usage. A bidirectional inverter serves as both an EV charger and a grid-interfacing converter, operating in multiple modes such as charging the EV battery, supplying stored energy back to the grid, and storing excess grid energy during low demand. The MCCF-PLL-based control system coordinates power flow among EV batteries, household loads, and the grid. MATLAB simulations validate the system's performance, showing enhanced power quality, grid stabilization during peak loads, and reliable backup power during blackouts. The system also meets IEEE-519 standards by keeping total harmonic distortion (THD) at 5%.
Conference papers on the topic "Enhanced FEM stability simulations"
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Oruc, Ilker, Rajiv Shenoy, Joseph Horn, and Jeremy Shipman. "Towards Real-Time Fully Coupled Flight Dynamics and CFD Simulations of the Helicopter/Ship Dynamic Interface." In Vertical Flight Society 72nd Annual Forum & Technology Display. The Vertical Flight Society, 2016. http://dx.doi.org/10.4050/f-0072-2016-11496.
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This study represents the ongoing efforts of a project whose ultimate goal is real-time virtual dynamic interface modeling and simulation with fully coupled Navier-Stokes CFD with a helicopter flight dynamics simulation. The coupling between GENHEL-PSU/CRUNCH CFD has been developed in a recent work and successful results of fully coupled flight dynamics and CFD simulations of rotorcraft/ship dynamic interface were presented. In the coupled simulations, the flight dynamics model is free to move within a computational domain, where the main rotor forces are converted to source terms in the momentum equations of the CFD solution. Simultaneously, the CFD solver calculates induced velocities that are fed back to the simulation and affect the aerodynamic loads in the flight dynamics. The CFD solver models the inflow, ground effect, and interactional aerodynamics in the flight dynamics simulation. An actuator disk model was used to map rotor blade loads into the computational domain. In order to enhance stability and efficiency of the CFD solution, rotor source terms are applied onto vertically stacked planes with a 1D Gaussian distribution. In this work, the simulation framework for fully coupled piloted flight dynamics/CFD is demonstrated for a simplified shedding wake example. Improvements to the coupling interface are described that allow the simulation to run at real-time execution speeds on currently available computing platforms, demonstrating a simulation framework for pilot-in-the-loop CFD (PILCFD) flight simulation.
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Punzi, Claudio, Eleonora Giovanardi, Federico D'Amico, Andrea Mancini, and Mark Crooks. "A Multidisciplinary Mid-fidelity Approach for Tiltrotor Wing Aeroelastic Design Based on structural Mesh Morphing." In Vertical Flight Society 80th Annual Forum & Technology Display. The Vertical Flight Society, 2024. http://dx.doi.org/10.4050/f-0080-2024-1149.
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This paper introduces a Multidisciplinary Design and Optimization (MDO) approach for the design of a tiltrotor wing, utilizing as test case a semi-wing with integrated nacelle and rotor. Structural integrity is assessed via stress analysis on a GFEM, which also forms the basis for a coupled wing-rotor aeroelastic model to ensure whirlflutter stability. Aerodynamic performance is assessed through CFD analysis of two-dimensional wing's airfoil shape. The MDO workflow leverages three levels of design space control that can influence the structural response of the wing: other than controlling the structural properties of composite materials, the internal wing-box architecture and external airfoil shape are modified acting directly on the FEM by means of a mesh morphing technique. This methodology allows for the use of mid-fidelity finite element models, bypassing CAD reshaping and remeshing. Validation tests confirm the approach's effectiveness in producing optimized designs. Additionally, the study explores surrogate models as efficient alternatives to CFD simulations, yielding sufficiently accurate results while reducing computational costs and the MDO simulation time.
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Annett, Martin, and J. Pereira. "Preliminary Assessment of Bird Strike on Low Noise Rotor Blade Sections." In Vertical Flight Society 74th Annual Forum & Technology Display. The Vertical Flight Society, 2018. http://dx.doi.org/10.4050/f-0074-2018-12737.
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One of the primary research themes for NASA's Revolutionary Vertical Lift Technology Project (RVLT) is evaluation of low-noise vertical lift concepts and configurations. A multidisciplinary design analysis and optimization (MDAO) process, which incorporates acoustics, structures, icing, and impact dynamics design constraints, is in development for the conceptual low-noise rotor blade design. Modifications to conventional rotor blade shape, cross section, and material selection to reduce noise may be limited by the capability of the structure to withstand a bird strike. The bird strike requirement for transport category rotorcraft is specified in 14 CFR §29.631, and requires safe flight and landing following impact of a 2.2 lb bird. An artificial bird simulant has been developed for repeatable laboratory testing, and consists of ballistic gelatin infused with phenolic microspheres. Ballistic testing of a bird simulant on various flat and wedge shaped objects was conducted at NASA Glenn Research Center's Gas Gun Facility. Force and strain data were compared to impact simulations of an LS-DYNA® finite element model (FEM). The bird simulant was modeled using Smooth Particle Hydrodynamics (SPH), and validated based on the data. The bird simulant model was incorporated with a low noise blade design that was verified for aeroelastic stability and contained dimensions typical of a medium lift category rotorcraft. FEM pre-processing capabilities were utilized to morph the cross section to different dimensions, and LS-DYNA analyses were conducted. A parametric assessment of damage will be discussed, with varying factors such as spar thickness, blade thickness, and nonlinear material strength parameters. The geometric constraints on this low noise blade that will be used for follow-on MDAO analyses are a combination of maximum blade twist of 15 degrees and a minimum spar thickness of 50% of the nominal spar thickness.
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Lisjak, A., L. He, J. Ha, B. S. A. Tatone, and O. K. Mahabadi. "Enhancement of an FDEM-Based Geomechanical Simulation Software with Hybrid FEM-FDEM and Elasto-Plastic Modeling Capabilities: Application to Slope Stability Analysis." In 58th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2024. http://dx.doi.org/10.56952/arma-2024-0620.
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ABSTRACT: The goal of this paper is to present recent developments aimed at improving computational efficiency and extending the range of material applicability of a 2D/3D FDEM geomechanical simulation software. Firstly, a hybrid FEM-FDEM logic was devised to allow for user-defined regions of the domain to be modeled as a continuum, while the remainder is captured by the FDEM formulation with an intrinsic cohesive zone model explicitly capturing fracturing. Benchmarking results indicate simulation speed-ups of up to 48x when using the new logic versus the traditional full FDEM approach. Secondly, the finite element formulation was enhanced with elasto-plastic constitutive models based on Drucker-Prager and Mohr-Coulomb failure criteria, effectively broadening the range of applicability to materials that exhibit irreversible damage processes under load without breaking. These developments were initially verified by comparing simulated stress distributions against analytical solutions for select boundary value problems. Practical validation of the novel FDEM formulation was achieved by capturing the variation of critical failure mechanism observed in a slope as a function of the type of rock mass jointing. The factors of safety computed with the strength reduction method compared very well with those reported in the literature for commercially available programs based on DEM and FEM. Finally, a direct comparison between FEM-based, elasto-plastic and FDEM-based, brittle-fracture models is presented for the case of a homogeneous rock slope. 1. INTRODUCTION The finite-discrete element method (FDEM) is a numerical method originally introduced by Munjiza et al. (1995) as a means of combining principles of continuum mechanics, such as the theory of elasticity and non-linear fracture mechanics, with discrete element algorithms to model fracture, fragmentation, and failure of cementitious materials and rocks. Building upon Munjiza's pioneering work, FDEM has been further developed by a multitude of research groups and organizations worldwide, and applied to a variety of rock mechanics and rock engineering problems where consideration of brittle fracturing processes is critical. Over the years, developments of FDEM have focused on several major areas of interest including (i) improvement of the core algorithms for deformation, fracture, interaction, and contact detection (e.g., Lei et al., 2016, Fukuda et al., 2021, Cai et al., 2023), (ii) incorporation of multi-physics capabilities to account for hydraulic and thermal effects (e.g., Yan and Jiao, 2018, Yan et al., 2019, Munjiza et al., 2020), and (iii) reduction of simulation run times by parallel computing (e.g., Lei et al., 2014; Lisjak et al., 2018; Fukuda et al, 2019). In the classic implementation of FDEM (Munjiza, 2004), the numerical representation of fractures is achieved by an intrinsic cohesive zone model (ICZM). With this approach, zero-thickness cohesive crack elements are inserted (at the beginning of the simulation) across pairs of adjacent solid finite elements throughout the entire modelling domain. All irreversible ("plastic") deformations are concentrated in the form of yielding and breakage of the interfaces between the solid finite elements, which remain elastic.
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Gerenda´s, Miklo´s, Yannick Cadoret, Christian Wilhelmi, et al. "Improvement of Oxide/Oxide CMC and Development of Combustor and Turbine Components in the HiPOC Program." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45460.
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Three different oxide/oxide ceramic matrix composite (CMC) materials are described. Design concepts for the attachment of the CMC component to the metal structure of the gas turbine are developed in a first work stream focused on the combustion chamber and the turbine seal segment. Issues like environmental barrier coating (EBC)/thermal barrier coatings (TBC), application and volatilization, allowance for the different thermal expansion and the mechanical fixation are addressed. The design work is accompanied by CFD and FEM simulations. A variation of the microstructural design of the three oxide/oxide CMC materials in terms of different fiber architecture and processing of matrix are considered. Also, mechanical properties of these variations are evaluated. The material concepts are developed further in a second work stream. The CMCs are tested in various loading modes (tension, compression, shear, off-axis loading) from room temperature to maximum application temperature focusing on tensile creep behavior. By modification of the matrix and the fiber-matrix interface as well as EBC coatings, the high temperature stability and the insulation performance are enhanced. An outline of the “High Performance Oxide Ceramic”-program HiPOC for the following years is given, including manufacturing of a high-pressure tubular combustor and turbine seal segments from the improved materials as technology samples, for which validation testing up to technology readiness level 4 is scheduled for 2011.
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Hammad, Abdullah, Fahad AlHosni, Muhammad Imran Khurshid, et al. "Drill String Optimization Across Multilateral Wells Breakthrough a New Benchmark of Performance and Enhanced Operation Integrity: Middle East Specific." In SPE/IADC Middle East Drilling Technology Conference and Exhibition. SPE, 2025. https://doi.org/10.2118/225699-ms.
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Abstract The drilling construction process in specific Middle Eastern fields presents unique challenges, especially when drilling multilateral wells. These laterals require the use of a tapered-string configuration, necessitating additional trips to incorporate 4-inch drill pipes (DPs) due to the liner profile design. These additional trips increase operational risks and extend drilling time. This manuscript outlines the implemented solutions, highlighting technical benefits and cost savings achieved by optimizing the drill string design. Traditionally, the 8.5-inch landing section is drilled with 5-inch DPs, while the 6.125-inch laterals require a tapered string of 5-inch and 4-inch DPs. Due to the shallow design of the 7-inch top-of-liner (TOL), each lateral requires an additional trip for inserting 4-inch DPs. A comprehensive study of torque and drag (T&D) and hydraulics was conducted to evaluate the feasibility of drilling both the landing and lateral sections exclusively with 4-inch DPs. Additionally, finite element analysis (FEA) was performed to assess dogleg severity (DLS) capabilities and shock levels. A full risk assessment was also conducted to address gaps related to health, safety, and environmental (HSE) factors and equipment quality. Performance evaluations show that 4-inch DPs, when used in both landing and lateral sections, consistently outperform 5-inch DPs by requiring less torque, providing greater dynamic stability, and reducing shock and vibration. Directional requirements in terms of DLS were achieved seamlessly in the landing section. Moreover, the compact size of 4-inch DPs optimizes dynamic drilling parameters, notably minimizing stick-slip incidents and mechanical-specific energy, thus enhancing drilling efficiency over traditional 5-inch or tapered DP applications. These improvements increased operational efficiency, resulting in cost savings of 0.5 days per well by eliminating the need for transitions between 5-inch and 4-inch DPs. Further savings of 1–1.5 days per well were achieved by eliminating unnecessary trips for repositioning 4-inch DPs. Additional savings were realized by removing the requirement for packer utilization to modify the blowout preventer (BOP) ram, reducing rig time by one full day. Overall, the reduction in operational activities led to improved operational integrity, enhanced drilling efficiency, and increased cost- effectiveness. This study provides a comparative evaluation of 4-inch versus 5-inch DPs, demonstrating how an optimized drill string selection can enhance performance while mitigating operational risks and costs. This paper addresses the knowledge gap in utilizing 4-inch drill pipes (DPs) in both the landing and lateral sections of multilateral wells, particularly in challenging environments where motorized rotary steerable system (RSS) bottom-hole assemblies (BHAs) are deployed. Through controlled simulations, finite element analyses, and field data from Middle Eastern operations – including drilling conditions with full or lost circulation—the study evaluates and compares the performance of 4-inch versus 5-inch DPs in 8½-inch landing sections and highlights the added value of 4-inch DPs in 6-1/8" horizontal sections. The findings related to hole cleaning, vibration management, and mechanical performance are based on this specific context, and the solutions and lessons presented can be applied globally following comprehensive risk assessments to validate their efficacy in similar well configurations.
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Elhassan, Azza, Patrick Manga, Mohamed S. Abdellatif, et al. "Impact of Change in Mud Weight & Offset Well Injection Pressure on Cement Sheath Integrity; Case Study for UAE Offshore Field." In ADIPEC. SPE, 2023. http://dx.doi.org/10.2118/216852-ms.
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Abstract As drilling horizontal wells became more complex with multiple production drains from various reservoirs, zonal isolation has become a key challenge to be achieved. Many studies have shown the impact of change in mud weight during drilling activities on wellbore stability, without considering the consequences on the set cement. This case study will be focusing on drilling activities on offset wells, evaluating & exploring how mud weight changes can affect wellbore instability and damage the cement sheath despite the fact that the cement evaluation logs showed good results days after the cement job and before the mud weight reduction. The wells being studied have been analyzed using Finite Element Analysis (FEA) modeling after the cement was set and exposed to a change in mud weight as well as being exposed to the offset injection well. FEA computer simulations have enabled this modelling to determine the optimal mechanical properties required for the cement slurries to withstand those load limits (pressure testing, pressure reduction due to change of mud weight or an increase of the pore pressure due to an offset injection well). After opening the window and drilling ahead through the production drain wellbore, the wells have the same tendency of instability and require an increase in mud weight to control the inflow. This paper presents the impacts of the offset wells and the change of mud weight on the cement sheath failure in debonding, cracking, or sheath deterioration leading to gas channeling due to a micro annulus. The considered wells present the same behavior that has been highlighted above. The question to ask is why did a well that has been cemented and recorded a good cement bond fail to provide proper zonal isolation? The injection pressure of the offset well was evaluated and then used in the simulations, considering the conventional cement used during the primary cement job. The analysis has shown a complete failure of the cement integrity: cement debonding from the casing or from the formation; cement cracking and sheath failure. The cement slurry with improved mechanical properties was employed for the study under the same pressure conditions from an offset well and mud weight change. The model results demonstrate that the new cement's ability to withstand stresses has improved on the wells cemented after this study. The modelling effort presented in this paper allows for a barrier to be designed that has enhanced mechanical properties compared to the already placed barrier on the offset wells in the same field. Aside from improving the set cement mechanical properties, the mud weight change design has been improved in such a way that the mud weight must be anticipated, decreasing its impact on the barrier.
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Shah, Sameer Rafiq, Dilip Kumar, and Nishant Tiwari. "Design and Development Of An In-Wheel Suspension With Novel Automatic Camber Control Strategy For Improved Handling." In FISITA World Congress 2021. FISITA, 2021. http://dx.doi.org/10.46720/f2020-vdc-081.
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In this era of electrification, HEVs are mainly focused on weight and space saving. This is done to ensure the maximum size of the battery package on the vehicle. This situation demands for a drive by wire systems which makes the vehicle lighter as well as more spacious. This paper introduces a new type of In-Wheel suspension has been introduced in this paper. The problem of large suspension systems and its bulkiness were studied. Vehicle instability while driving and cornering was also stated. And the suspension's capability to handle uneven tyre wear which is caused due to improper or fixed camber angle was also addressed. The Novel In-Wheel Suspension is introduced in this paper which houses all the crucial parts of the suspension inside the rim of the wheel thus making it compact, lighter and sturdy. Parts were first designed by the principles of Machine Design, Kinematics and Mechanics of Materials. They were later modelled on Solid Edge ST7. Structural simulations was carried out on FEA Solver under highly strained conditions and also under dynamic loading and the results were satisfactory. A scaled prototype was made by manufacturing the parts on CNC machine. Later the suspension was assembled by brazing the parts together. The Impulse hammer technique was used to carry out the modal analysis which was used to study the damping characteristics of the suspension. Another innovation is introduced in this suspension which the Novel concept of Automatic Camber Control strategy which calibrates the camber angle of the wheel in real-time and greatly improves the performance as well as stability of the vehicle. The design process involved understanding the scaling down the size of the suspension without compensating the functionality of the suspension. The working prototype of the suspension was constructed and after rigorous testing which were carried out. It was found that the performance of suspension under low traction conditions was enhanced.
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Wu, Huanyu, Qi Zhao, Jiayi Shen, and Hanze Li. "Numerical Simulation of the Underground Storage Cavern Using FDEM." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0282.
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ABSTRACT Underground storage cavern has been increasingly exploited as it has many advantages such as reducing investment, economizing land use and improving safety compared with storage above the ground surface. We employ the hydromechanical coupled FDEM to simulate the excavation and operation phases of the underground storage cavern with a water curtain system (WCS), taking into consideration the natural discrete fracture network (DFN). The simulation results captured the propagation and slipping of the pre-existing DFN during the excavation and operation process. We quantitatively evaluate the containment performance based on the water inflow and pore pressure distribution. This study provides new insights into evaluating the stability of cavern-surrounding rock masses and containment performance of underground storage caverns. INTRODUCTION Underground storage caverns have better performance on safety, security, economy, and greater environmental acceptance compared with traditional storage infrastructures such as storage tanks and pipelines. Several large underground storage caverns have been constructed, for example, Jurong rock caverns in Singapore (Zhou & Zhao, 2016) and Huangdao underground oil storage caverns in China (Wang et al., 2015). Underground storage caverns are constructed in fractured rock masses, confining the storage medium (such as oil and gas) by maintaining groundwater pressure around caverns which is also called hydraulic confinement (Aberg, 1978; Froise, 1987; Lindblom, 1997). The basic principle of underground containment the cavern is that no gas could leak as long as the water pressure increases along all possible gas leakage paths away from the cavern (Goodall et al., 1988). To enhance the sealing performance, water curtain systems (WCS) are constructed to manually control the pore pressure distribution by regulating the water curtain pressure. (Shi et al., 2018). Previous studies has evaluated the stability of excavated rock masses (Mohanty & Vandergrift, 2012; Ma et al., 2016; Zhuang et al., 2017) and containment performance (Xu et al., 2018; Liu et al., 2021) by using in-situ monitoring methods and numerical simulation. However, the fracture propagation and slip induced by the excavation and operation of the storage cavern, as well as the resultant fluid pressure variation, have not been illustrated.
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Ali, H., M. Shahzaib, M. Z. Emad, M. Waqas, and W. Ijaz. "Stability Analysis of a Tunnel Nearby Folded Strata Using Numerical Modeling." In 58th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2024. http://dx.doi.org/10.56952/arma-2024-0862.
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ABSTRACT: The stability of underground structures, like mines and tunnels, has always been a major concern in the field of underground space development works. Reliable prediction of tunnel stability is a key challenge for tunnel engineering, especially when drilling in folded rock masses. Folded strata are layers of rock that have been folded and deformed by tectonic forces. This can create complex geological structures that are difficult for tunnel engineers. This research aims to investigate the stability of tunnels through folded strata (anticline, syncline, and fracture zones). Failure Sequence of the tunnel is simulated using finite difference software. The results of the simulations are analyzed to identify potential failure mechanisms and assess their likelihood and consequences. Based on these simulations, innovative techniques (position and number of tunnels) are developed to enhance tunnel stability in the fold-rich region. The results suggest that FDM software can be used to identify potential areas of instability and to design appropriate mitigation measures. This could help to reduce the risk of tunnel collapse and improve the safety of tunnels in areas with folded strata. 1. INTRODUCTION The stability of subterranean structures within folded rock formations is of paramount importance. As urban populations grow and the tunneling industry expands, the proliferation of new underground structures introduces novel challenges to their stability. Each project presents unique geological and geomechanical complexities, necessitating the development of reliable stability assessment methodologies and simulation techniques. This imperative has long been recognized, with ongoing research efforts aimed at comprehensively understanding the behavior of underlying strata when subjected to various structural interventions. Recent studies by scholars such as (Rama Sastry, 2023), (Li Li, 2023), and (Zhiming Li, 2023) have addressed tunnel stability issues arising from diverse geological features encountered during excavation worldwide. Utilizing laboratory testing and software-based modeling, these researchers have sought to identify and mitigate specific challenges associated with faults, joints, soft rock/sand layers, and other discontinuities. However, a notable research gap persists concerning the study of folded strata in tunnel construction. Folded strata present a multitude of complications, including localized stress concentration, tunnel alignment deviations, support challenges, and water ingress, culminating in structural failures. Case studies conducted by (Kasser, 2007; Lüthi, 2016; Marti, 2010; McCullough, 2017; Overman, 2013) underscore the significance of folded strata-induced failures in tunnel projects worldwide. Despite efforts to diagnose the root causes of these failures, effective solutions remain elusive. Thus, this research endeavors to address this gap by developing a numerical model simulating hypothetical folded strata configurations along tunnel faces, thereby elucidating failure scenarios and potential remedies.
Reports on the topic "Enhanced FEM stability simulations"
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Arduino, Pedro, Long Chen, and Christopher McGann. Estimation of Shear Demands on Rock Socketed Drilled Shafts subjected to Lateral Loading. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, 2018. http://dx.doi.org/10.55461/nsos1322.
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This report presents results of an evaluation study on the applicability of current design procedures (based on p-y curves) to the analysis of large-diameter shafts socketed in rock, and the identification of enhanced moment transfer mechanisms not considered in current design methodologies. For this purpose simplified models, and possible three-dimensional (3D) finite-element method (FEM) models are studied to shed some light on the response of drilled shafts socketed in rock. A parametric study using p-y and considering a wide range of rock properties and rock-socket depths, different criteria to define the soil and rock p-y curves, different beam theories, and different interface frictional resistances are presented and compared with 3D FEM simulations. A new element is discussed to account for the shaft toe and underlain rock interaction, which could provide benefit to reduce shear demands when the socket is shallow.
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Heinz, Kevin, Itamar Glazer, Moshe Coll, Amanda Chau, and Andrew Chow. Use of multiple biological control agents for control of western flower thrips. United States Department of Agriculture, 2004. http://dx.doi.org/10.32747/2004.7613875.bard.
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The western flower thrips (WFT), Frankliniella occidentalis (Pergande), is a serious widespread pest of vegetable and ornamental crops worldwide. Chemical control for Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) on floriculture or vegetable crops can be difficult because this pest has developed resistance to many insecticides and also tends to hide within flowers, buds, and apical meristems. Predatory bugs, predatory mites, and entomopathogenic nematodes are commercially available in both the US and Israel for control of WFT. Predatory bugs, such as Orius species, can suppress high WFT densities but have limited ability to attack thrips within confined plant parts. Predatory mites can reach more confined habitats than predatory bugs, but kill primarily first-instar larvae of thrips. Entomopathogenic nematodes can directly kill or sterilize most thrips stages, but have limited mobility and are vulnerable to desiccation in certain parts of the crop canopy. However, simultaneous use of two or more agents may provide both effective and cost efficient control of WFT through complimentary predation and/or parasitism. The general goal of our project was to evaluate whether suppression of WFT could be enhanced by inundative or inoculative releases of Orius predators with either predatory mites or entomopathogenic nematodes. Whether pest suppression is best when single or multiple biological control agents are used, is an issue of importance to the practice of biological control. For our investigations in Texas, we used Orius insidiosus(Say), the predatory mite, Amblyseius degeneransBerlese, and the predatory mite, Amblyseius swirskii(Athias-Henriot). In Israel, the research focused on Orius laevigatus (Fieber) and the entomopathogenic nematode, Steinernema felpiae. Our specific objectives were to: (1) quantify the spatial distribution and population growth of WFT and WFT natural enemies on greenhouse roses (Texas) and peppers (Israel), (2) assess interspecific interactions among WFT natural enemies, (3) measure WFT population suppression resulting from single or multiple species releases. Revisions to our project after the first year were: (1) use of A. swirskiiin place of A. degeneransfor the majority of our predatory mite and Orius studies, (2) use of S. felpiaein place of Thripinema nicklewoodi for all of the nematode and Orius studies. We utilized laboratory experiments, greenhouse studies, field trials and mathematical modeling to achieve our objectives. In greenhouse trials, we found that concurrent releases of A.degeneranswith O. insidiosusdid not improve control of F. occidentalis on cut roses over releases of only O. insidiosus. Suppression of WFT by augmentative releases A. swirskiialone was superior to augmentative releases of O. insidiosusalone and similar to concurrent releases of both predator species on cut roses. In laboratory studies, we discovered that O. insidiosusis a generalist predator that ‘switches’ to the most abundant prey and will kill significant numbers of A. swirskiior A. degeneransif WFTbecome relatively less abundant. Our findings indicate that intraguild interactions between Orius and Amblyseius species could hinder suppression of thrips populations and combinations of these natural enemies may not enhance biological control on certain crops. Intraguild interactions between S. felpiaeand O. laevigatus were found to be more complex than those between O. insidiosusand predatory mites. In laboratory studies, we found that S. felpiaecould infect and kill either adult or immature O. laevigatus. Although adult O. laevigatus tended to avoid areas infested by S. felpiaein Petri dish arenas, they did not show preference between healthy WFT and WFT infected with S. felpiaein choice tests. In field cage trials, suppression of WFT on sweet-pepper was similar in treatments with only O. laevigatus or both O. laevigatus and S. felpiae. Distribution and numbers of O. laevigatus on pepper plants also did not differ between cages with or without S. felpiae. Low survivorship of S. felpiaeafter foliar applications to sweet-pepper may explain, in part, the absence of effects in the field trials. Finally, we were interested in how differential predation on different developmental stages of WFT (Orius feeding on WFT nymphs inhabiting foliage and flowers, nematodes that attack prepupae and pupae in the soil) affects community dynamics. To better understand these interactions, we constructed a model based on Lotka-Volterra predator-prey theory and our simulations showed that differential predation, where predators tend to concentrate on one WFT stage contribute to system stability and permanence while predators that tend to mix different WFT stages reduce system stability and permanence.