The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Subhash Rakheja - One of the best experts on this subject based on the ideXlab platform.
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relative ride performance analysis of a torsio elastic suspension applied to front rear and both axles of an off road vehicle
International Journal of Heavy Vehicle Systems, 2019Co-Authors: Mu Chai, Subhash Rakheja, Wen Bin ShangguanAbstract:Relative ride performance potentials of a torsio-elastic suspension applied to front or rear or both axles of an off-road vehicle are investigated. A three-dimensional vehicle model, incorporating a torsio-elastic suspension, is used to evaluate relative ride responses with different suspension arrangements. The model validity is demonstrated using the reported field-measured responses of a rear-suspended forestry vehicle. The optimal parameters of the suspension configurations are identified by minimising the vector sum of av and frequency-weighted rotational vibration. Relative ride performance potentials of different suspensions are subsequently investigated for the loaded and unloaded vehicle in terms of frequency-weighted rms accelerations. The results show that the torsio-elastic suspension is relatively insensitive to variations in vehicle load. It is shown that the suspension applied to axle of the vehicle unit supporting driver cabin is more effective in limiting driver vibration, while preserving effective Roll Stiffness. The fully-suspended vehicle, however, yields most effective vibration attenuation.
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KINETOSTATIC ANALYSIS OF A BEAM-AXLE SUSPENSION WITH PANHARD ROD RESTRAINING LINKAGE
International Journal of Vehicle Design, 2014Co-Authors: Ion Stiharu, Subhash RakhejaAbstract:Kinetostatic response characteristics of a beam–axle suspension comprising a transversal Panhard rod constraint are evaluated as a function of the suspension geometry, vertical load and lateral force arising from a steady turning manoeuvre. A Roll plane model of a road vehicle is developed incorporating the kinematic constraint posed by the transverse linkage. The non–linear algebraic equations governing the Roll plane kinematic motion are formulated and solved using the Newton iterative techniques. The kinetostatic response characteristics are evaluated in terms of the body Roll, effective Roll Stiffness and variations in the coordinates of the Roll centre for various geometric parameters. The coordinates of the suspension Roll centre and sprung mass cg are determined from the algebraic equations developed by vector loop method. The results of the study show that the suspension spring rate and the location and orientation of the Panhard rod influence the kinetostatic Roll properties of the suspension in a significant manner, when the vehicle is subiect to vertical and lateral forces.
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Dynamic analyses of Roll plane interconnected hydro-pneumatic suspension systems
International Journal of Vehicle Design, 2008Co-Authors: Dingcai Cao, Subhash RakhejaAbstract:Concepts in Roll-interconnected hydro-pneumatic suspensions with hydraulic and pneumatic couplings are developed and analysed for enhancement of anti-Roll properties of heavy vehicles. The mathematical models of the Roll-coupled suspensions are formulated considering the fluid properties and variable damping valves. The Roll properties of fluidically connected suspensions are compared with those of unconnected suspensions with and without anti-Roll bar, and dynamic responses of a heavy vehicle with different suspensions are investigated under excitations arising from road roughness and directional manoeuvres. The results indicate that both interconnected suspensions could considerably improve Roll Stiffness without affecting vertical ride, while hydraulic interconnections could further enhance the Roll mode damping properties.
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ANALYSIS OF A TWIN-GAS-CHAMBER HYDRO-PNEUMATIC VEHICLE SUSPENSION
Advances in Dynamics Instrumentation and Control, 2007Co-Authors: Dongpu Cao, Subhash Rakheja, A. K. W. AhmedAbstract:A hydro-pneumatic suspension strut concept with integrated two gas chambers is proposed to realize nearly symmetric Stiffness properties in compression and rebound, and progressively hardening Roll stifbess characteristics. Fundamental Stiffness properties of the proposed strut suspension are compared with the suspension involving one-gas-chamber struts with an antiRoll bar, in terms of suspension rate and Roll Stiffness. Dynamic responses are performed under a range of road inputs and vehicle velocities, and an excitation arising kom a steady turning maneuver. The simulation results of Stiffness properties indicate that the suspension rate of the twin-gas-chamber strut suspension can be designed to achieve soft vertical ride around static ride height and progressively hardening properties in both compression and rebound, which could help realize hardening effects in Roll Stiffness, compared with the softening effects in Roll Stiffness characteristics of suspensions with one-gas-chamber struts or commercial air springs. The dynamic responses demonstrate that the twin-gas-chamber strut suspension could considerably enhance the Roll performance of heavy vehicles and slightly improve suspension travel responses, with negligible influence on vertical and Roll ride.
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Roll plane analysis of a hydro-pneumatic suspension with twin-gas-chamber struts
International Journal of Heavy Vehicle Systems, 2007Co-Authors: Dongpu Cao, Subhash RakhejaAbstract:A hydro-pneumatic strut comprising two gas chambers is proposed to realise nearly symmetric vertical Stiffness properties in compression and rebound, and progressively hardening Roll Stiffness. The fundamental properties of the proposed struts are derived in terms of suspension rate and Roll Stiffness through formulations of strut forces in the Roll plane of a vehicle. Dynamic responses are investigated under excitations arising from vehicle-road interactions and a steady centrifugal acceleration. The results demonstrate that the suspension with proposed struts could reduce ride height drift, and improve suspension topping, tyre deflection and Roll response characteristics, with negligible influence on vertical and Roll ride.
Zengcai Wang - One of the best experts on this subject based on the ideXlab platform.
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Gain-Scheduling Control of Vehicle Roll Stiffness Distribution
2007 International Conference on Mechatronics and Automation, 2007Co-Authors: Xiujian Yang, Zengcai WangAbstract:The influence of lateral load transfer on vehicle's handling and stability is analyzed via a 3 degree of freedom (3 DOF) vehicle dynamics model. A proper distribution of front and rear Roll Stiffness to control the lateral load transfer on the front and rear axles can improve the vehicle's handling and stability obviously. A Roll Stiffness distribution control scheme is proposed based on gain-scheduling technique, for intense nonlinearity exists between tire and road and a precise mathematical model is difficult to obtain between the Roll Stiffness contRolling and the handling, stability of the vehicle. A PID contRoller taking a semi-active suspension as the actuator is designed, whose gains can be tuned to adapt the changing of the running condition and an optimal Roll Stiffness distribution can be obtained. Some simulation results demonstrate that the vehicle handling and stability can be improved efficiently in the linear region of the tire, though it is difficult to bring the vehicle back to stability when the tire has fallen into saturation. So it may be a good method to take Roll Stiffness control as a complement for the vehicle stability control.
Jong Min Kim - One of the best experts on this subject based on the ideXlab platform.
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Vehicle’s New Anti-Roll System for Suspension Parasitic Stiffness Reduction and Non-Linear Roll Stiffness Characteristic
Volume 13: Transportation Systems, 2013Co-Authors: Bo Min Kim, Jong Min KimAbstract:In general, vehicle uses torsional Stiffness of a stabilizer bar to control the Roll motion. But this stabilizer bar system has problems with degradation for ride comfort and vehicle’s NVH characteristic due to the suspension parasitic Stiffness caused by deformation and wear of the stabilizer bar rubber bush. In addition, it is difficult to control the vehicle’s Roll motion effectively in case of excessive vehicle Roll behavior when it is designed to satisfy ride comfort simultaneously because of the stabilizer bar’s linear Roll Stiffness characteristic. In this paper, the new anti-Roll system is suggested which consists of connecting link, push rod, laminated leaf spring, and rotational bearing. This new concept anti-Roll system can minimize the suspension parasitic Stiffness by using rotational bearing structure and give the vehicle non-linear Roll Stiffness by using the laminated leaf spring structure which are composed of main spring and auxiliary one. Reduction of suspension parasitic Stiffness and realization of non-linear Roll Stiffness in this anti-Roll system were verified with both vehicle dynamic simulation and vehicle test. Also, this study includes improvement of the system operating efficiency through material change and shape optimization of the leaf spring, and optimal configuration of the force transfer system.Copyright © 2013 by ASME
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vehicle s new anti Roll system for suspension parasitic Stiffness reduction and non linear Roll Stiffness characteristic
ASME 2013 International Mechanical Engineering Congress and Exposition, 2013Co-Authors: Bo Min Kim, Jong Min KimAbstract:In general, vehicle uses torsional Stiffness of a stabilizer bar to control the Roll motion. But this stabilizer bar system has problems with degradation for ride comfort and vehicle’s NVH characteristic due to the suspension parasitic Stiffness caused by deformation and wear of the stabilizer bar rubber bush. In addition, it is difficult to control the vehicle’s Roll motion effectively in case of excessive vehicle Roll behavior when it is designed to satisfy ride comfort simultaneously because of the stabilizer bar’s linear Roll Stiffness characteristic. In this paper, the new anti-Roll system is suggested which consists of connecting link, push rod, laminated leaf spring, and rotational bearing. This new concept anti-Roll system can minimize the suspension parasitic Stiffness by using rotational bearing structure and give the vehicle non-linear Roll Stiffness by using the laminated leaf spring structure which are composed of main spring and auxiliary one. Reduction of suspension parasitic Stiffness and realization of non-linear Roll Stiffness in this anti-Roll system were verified with both vehicle dynamic simulation and vehicle test. Also, this study includes improvement of the system operating efficiency through material change and shape optimization of the leaf spring, and optimal configuration of the force transfer system.Copyright © 2013 by ASME
A. K. W. Ahmed - One of the best experts on this subject based on the ideXlab platform.
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ANALYSIS OF A TWIN-GAS-CHAMBER HYDRO-PNEUMATIC VEHICLE SUSPENSION
Advances in Dynamics Instrumentation and Control, 2007Co-Authors: Dongpu Cao, Subhash Rakheja, A. K. W. AhmedAbstract:A hydro-pneumatic suspension strut concept with integrated two gas chambers is proposed to realize nearly symmetric Stiffness properties in compression and rebound, and progressively hardening Roll stifbess characteristics. Fundamental Stiffness properties of the proposed strut suspension are compared with the suspension involving one-gas-chamber struts with an antiRoll bar, in terms of suspension rate and Roll Stiffness. Dynamic responses are performed under a range of road inputs and vehicle velocities, and an excitation arising kom a steady turning maneuver. The simulation results of Stiffness properties indicate that the suspension rate of the twin-gas-chamber strut suspension can be designed to achieve soft vertical ride around static ride height and progressively hardening properties in both compression and rebound, which could help realize hardening effects in Roll Stiffness, compared with the softening effects in Roll Stiffness characteristics of suspensions with one-gas-chamber struts or commercial air springs. The dynamic responses demonstrate that the twin-gas-chamber strut suspension could considerably enhance the Roll performance of heavy vehicles and slightly improve suspension travel responses, with negligible influence on vertical and Roll ride.
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DYNAMIC RIDE PROPERTIES OF A Roll-CONNECTED VEHICLE SUSPENSION
Current Advances in Mechanical Design and Production VII, 2000Co-Authors: Subhash Rakheja, A. K. W. Ahmed, Pj Liu, Marc J. RichardAbstract:Static and dynamic properties of a vehicle suspension comprising hydraulic struts interconnected in the Roll plane are investigated. The feedback effects due to fluid flow through the connecting pipes on the suspension Stiffness and damping properties are derived and discussed. Fundamental properties of the interconnected suspension are compared with those of an unconnected suspension with and without an anti-Roll bar, in terms of load-carrying capacity, suspension rate, Roll Stiffness and damping characteristics. The anti-Roll performance of the interconnected suspension is analyzed for centrifugal acceleration excitations encountered during directional maneuvers. The ride quality performance is evaluated for excitations occurring at the tire-road interface. It is concluded that the interconnected suspension with inherent enhanced Roll Stiffness and damping characteristics can significantly improve the heave ride performance and limit the body Roll motion.
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PROPERTIES OF AN INTERCONNECTED HYDRO-PNEUMATIC SUSPENSION SYSTEM
Transactions of the Canadian Society for Mechanical Engineering, 1995Co-Authors: Pj Liu, Subhash Rakheja, A. K. W. AhmedAbstract:The static and dynamic properties of a vehicle suspension comprising hydraulic struts interconnected in the Roll plane are investigated. The fundamental properties of the interconnected suspension are investigated and compared to those of the unconnected suspensions with and without the anti-Roll bar, in terms of load-carrying capacity, suspension rate, Roll Stiffness as well as damping characteristics. The anti-Roll performance of the interconnected suspension is analyzed for excitations encountered during directional manoeuvres. The ride quality performance is evaluated for excitations occurring at tire-road interface. It is concluded that the interconnected hydro-pneumatic suspension with inherent enhanced Roll Stiffness and damping characteristics can significantly restrict the body Roll motion to achieve improved Roll stability of a vehicle.
Nong Zhang - One of the best experts on this subject based on the ideXlab platform.
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Modal and Dynamic Analysis of a Vehicle with Kinetic Dynamic Suspension System
Shock and Vibration, 2016Co-Authors: Bangji Zhang, Nong Zhang, Jie Zhang, Jin QiutanAbstract:A novel kinetic dynamic suspension (KDS) system is presented for the cooperative control of the Roll and warp motion modes of off-road vehicles. The proposed KDS system consists of two hydraulic cylinders acting on the antiRoll bars. Hence, the antiRoll bars are not completely replaced by the hydraulic system, but both systems are installed. In this paper, the vibration analysis in terms of natural frequencies of different motion modes in frequency domain for an off-road vehicle equipped with different configurable suspension systems is studied by using the modal analysis method. The dynamic responses of the vehicle with different configurable suspension systems are investigated under different road excitations and maneuvers. The results of the modal and dynamic analysis prove that the KDS system can reduce the Roll and articulation motions of the off-road vehicle without adding extra bounce Stiffness and deteriorating the ride comfort. Furthermore, the Roll Stiffness is increased and the warp Stiffness is decreased by the KDS system, which could significantly enhance handing performance and off-road capability.
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Characteristic Analysis of Roll and Pitch Independently ContRolled Hydraulically Interconnected Suspension
SAE International Journal of Commercial Vehicles, 2014Co-Authors: Nong ZhangAbstract:ABSTRACT This paper presents the modeling and characteristic analysis of Roll-plane and pitch-plane combined Hydraulically Interconnected Suspension (HIS) system. Vehicle dynamic analysis is carried out with four different configurations for comparison. They are: 1) vehicle with spring-damper only, 2) vehicle with Roll-plane HIS, 3) vehicle with pitch-plane HIS and 4) vehicle with Roll and pitch combined HIS. The modal analysis shows the unique modes-decoupling property of HIS system. The Roll-plane HIS increases Roll Stiffness only without affecting other modes, and similarly pitch-plane HIS increases the pitch Stiffness only with minimum influence on other modes. When Roll and pitch plane HIS are integrated, the vehicle ride comfort and handling stability can be improved simultaneously without compromise. A detailed analysis and discussion of the results are provided to conclude the paper. CITATION: Xu, G. and Zhang, N., "Characteristic Analysis of Roll and Pitch Independently ContRolled Hydraulically Interconnected Suspension,"
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Modelling, Parameter Estimation and Testing of a Vehicle with Anti-Roll Systems
2010Co-Authors: Lifu Wang, Nong ZhangAbstract:In this paper a 4-DOF half-car model is developed for the study of vehicle anti-Roll systems, such as anti-Roll bars, hydraulically interconnected suspensions and active suspensions. The paper covers three parts: vehicle modelling, parameter estimation and experimental comparison of two passive anti-Roll systems. For the vehicle model, a torsional spring is adopted to represent the equivalent Roll Stiffness of an anti-Roll system. The advantage of this model is that, by separating the anti-Roll system from vehicle model, the vehicle parameter and anti-Roll system parameters can be estimated separately. Furthermore, the different anti-Roll systems can be compared easily with the same vehicle condition through increased vehicle Roll Stiffness. A practical approach is presented to estimate the vehicle model parameters, employing State Variable Method to extract systems transition matrix from vehicle free decay tests through a single channel measurement. By solving the eigenvalue problem of the derived transition matrix, system modal parameters such as natural frequencies and damping ratios can be obtained. Next step is to reconstruct the system matrix from the obtained eigenvalue, so called the inverse eigenvalue problem. As the system matrix must exist and the form is known from the modelling, a numerical solution is employed to estimate the mass-spring parameters in the vehicle model. Additionally, the vehicle damping parameters are estimated separately, by assuming that tyre damping is negligible and suspension damping is the only damping in the vehicle model. With the estimated parameter values, the simulations match the experimental results well in vehicle bounce and Roll mode tests. Furthermore, an anti-Roll bar system and a passive Hydraulically Interconnected Suspension (HIS) system are compared in this part. Each system has been installed on the same vehicle and tested under the same conditions. Both systems increase vehicle's Roll Stiffness but through different means. Using the vehicle parameter estimation approach abovementioned, the equivalent Roll Stiffness of antiRoll systems are estimated from experimental data. The two passive anti-Roll systems are compared in detail and discussions are also provided.
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Robust ContRoller Design for Improving Vehicle Roll Control
International Journal of Automotive Technology, 2007Co-Authors: Nong ZhangAbstract:This paper presents a robust contRoller design approach for improving vehicle dynamic Roll motion performance and guaranteeing the closed-loop system stability in spite of vehile parameter variations resulting from aging elements, loading patterns, and driving conditions, etc. The designed contRoller is linear parameter-varying (LPV) in terms of the time-varying parameters; its control objective is to minimise the H ∞ performance from the steering input to the Roll angle while satisfying the closed-loop pole placement constraint such that the optimal dynamic Roll motion performance is achieved and robust stability is guaranteed. The sufficient conditions for designing such a contRoller are given as a finite number of linear matrix inequalities (LMIs). Numerical simulation using the three-degree-of-freedom (3-DOF) yaw-Roll vehicle model is presented. It shows that the designed contRoller can effectively improve the vehicle dynamic Roll angle response during J-turn or fishhook maneuver when the vehicle’s forward velocity and the Roll Stiffness are varied significantly.
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Transient Characteristics of a Hydraulically Interconnected Suspension System
SAE Technical Paper Series, 2007Co-Authors: Jm Jeyakumaran, Wade A. Smith, Nong ZhangAbstract:This paper describes vehicle dynamic models that capture the large amplitude transient characteristics of a passive Hydraulically Interconnected Suspension (HIS) system. Accurate mathematical models are developed to represent pressure-flow characteristics, fluid properties, damper valves, accumulators and nonlinear coupling between mechanical and fluid systems. The vehicle is modeled as a lumped mass system with half- and fullcar configurations. The transient performance is demonstrated by numerical integration of the secondorder nonlinear differential equations. The Stiffness and damping characteristics corresponding to vehicle bounce, Roll and pitch motions are extracted from the transient simulation. Simulation results clearly demonstrate the superiority of the HIS system during vehicle handling and stability by providing additional Roll Stiffness and reduced articulation Stiffness.
