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The Effect of Friction on Ride Comfort Simulation and Suspension Optimization

Ebco Inc.-Peijun Xu
Huazhong University of Science and Technology-Wang Xuwang, Xiaoyu Chen, Yunqing Zhang
  • Technical Paper
  • 2020-01-0765
To be published on 2020-04-14 by SAE International in United States
The design of suspension affects the vehicle dynamics such as ride comfort and handling stability. Nonlinear characteristics and friction are important characteristics of suspension system, and the influence on vehicle dynamic performance cannot be ignored. Based on the seven-degree-of-freedom vehicle vibration nonlinear model with friction, the vibration response process of the vehicle and the influence of suspension friction on vehicle ride comfort and suspension action process were studied. The results show that friction will significantly affects the simulation of ride comfort and coincide with the function of the shock absorber. The suspension shock absorbers of vehicles were optimized with and without suspension friction. The results showed that the suspension tended to choose softer shock absorbers when there was friction. However, both of the two optimizations are able to improve the ride comfort of vehicles, and the simulation results were similar. At the same time, it was found that the better the dynamic performance of the vehicle model, the greater the influence of suspension friction on the simulation results of ride comfort.
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Multi-Mode Controller Design for Active Seat Suspension with Energy-Harvesting

Ebco Inc.-Peijun Xu
Huazhong University of Science and Technology-Zhenrui Zhang, Yunqing Zhang
  • Technical Paper
  • 2020-01-1083
To be published on 2020-04-14 by SAE International in United States
In this paper, a multi-mode active seat suspension with a single actuator is proposed and built. A one-DOF seat suspension system is modelled based on a quarter car model of commercial vehicle with an actuator which is comprised of a DC motor and a gear reducer. Aiming at improving ride comfort and reducing energy consumption, a multi-mode controller is established. According to the seat vertical acceleration and suspension dynamic travel signals, control strategies switch between three modes: active drive mode, energy harvesting mode and plug breaking mode. In active drive mode, the DC motor works in driving state and its output torque which calculated by LQR algorithm is controlled by a current-loop controller; In energy harvesting mode, the DC motor works in generator state by which induced current can charge the power source, in this mode, the DC motor is considered as a damper which damping coefficient is decided by the charging current and controlled by Skyhook algorithm; In plug breaking mode, the DC motor works in the plug breaking state and its inverse voltage…
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Filled Rubber Isolator’s Constitutive Model and Application to Vehicle Multi-Body System Simulation: A Literature Review

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Ebco, Inc.-Peijun Xu
Huazhong University of Science and Technology-Xingxing Feng, Yunqing Zhang
  • Journal Article
  • 10-02-02-0007
Published 2018-06-05 by SAE International in United States
Rubber elements present highly nonlinear mechanical properties affected by frequency and amplitude of excitation, prestrain and temperature, etc. Finite element (FE) models and lumped parameter models can be distinguished in the development of constitutive models of rubbers. Based on the concept of overlay model, different kinds of viscoelastic, or frequency-dependent models, and elastoplastic/friction, or amplitude-dependent models, are compared in terms of their modelling approach, parameters identification process and applications. Prestrain-dependent models and temperature-dependent thermo-mechanical models are also reviewed, including some special models which are not based on the concept of the overlay model. Experimental and computational studies of cylindrical bushings subjected to coupled deformation modes are analyzed and discussed. It is the hope that this literature review work can help clarify and guide the future research and development direction about rubber constitutive modelling.
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Mount Model Dependent on Amplitude and Frequency for Automotive Powertrain Mounting System

Ebco Inc.-Peijun Xu
Huazhong University of Science and Technology-Tianqi Lv, Xingxing Feng, Yunqing Zhang
Published 2017-03-28 by SAE International in United States
Three constitutive models which capture the amplitude and frequency dependency of filled elastomers are implemented for the conventional engine mounts of automotive powertrain mounting system (PMS). Firstly, a multibody dynamic model of a light duty truck is proposed, which includes 6 degrees of freedom (DOFs) for the PMS. Secondly, Three constitutive models for filled elastomers are implemented for the engine mounts of the PMS, including: (1) Model 1: Kelvin-Voigt model; (2) Model 2: Fractional derivative Kelvin-Voigt model combined with Berg’s friction; (3) Model 3: Generalized elastic viscoelastic elastoplastic model. The nonlinear behaviors of dynamic stiffness and damping of the mounts are investigated. Thirdly, simulations of engine vibration dynamics are presented and compared with these models and the differences between common Kelvin-Voigt model and other constitutive models are observed and analyzed.
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Ride Analysis under a Random Road Model with Interval Parameters

Ebco Inc.-Peijun Xu
Huazhong University of Science and Technology-Penglei Fu, Yunqing Zhang
Published 2017-03-28 by SAE International in United States
This work is motivated by the fact that the surface of a terrain may vary with local pavement properties and number of passes of the vehicle, which means the roughness coefficient and waviness of the terrain may vary in specific intervals. However, in traditional random terrain models, the roughness coefficient and waviness of the terrain are assumed as constants. Therefore, this assumption may be not very reasonable. A novel random terrain model is presented where the roughness coefficient and waviness of the terrain are expressed by interval numbers instead of constants. A 5-degree-of-freedom ride dynamic model of the vehicle with uncertain parameters is derived. The power spectral density (PSD) and root mean square value (RMS) of the vehicle ride responses are shown and analyzed. Analysis results indicate that the vehicle responses vary in specific intervals under the random terrain excitation with interval parameters.
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Powertrain Motion Control Analysis under Quasi-Static Extreme Loads

Ebco Inc.-Peijun Xu
Huazhong University of Science and Tech-Tianqi Lv, Yunqing Zhang
Published 2016-04-05 by SAE International in United States
The powertrain mounting system (PMS) plays an important role in improving the NVH (Noise, Vibration, Harshness) quality of the vehicle. In all running conditions of a vehicle, the displacements of the powertrain C.G. should be controlled in a prescribed range to avoid interference with other components in the vehicle. The conventional model of PMS is based on vibration theory, considering the rotation angles are small, ignoring the sequence of the rotations. However, the motion of PMS is in 3D space with 3 translational degrees of freedom and 3 rotational degrees of freedom, when the rotation angles are not small, the conventional model of PMS will cause errors. The errors are likely to make powertrain interfering with other components. This paper proposes a rigid body mechanics model of the powertrain mounting system. When the powertrain undergoes a large rotational motion, the rigid body mechanics model can provide more accurate calculation results. The quasi-static equation for solving displacements of the powertrain C.G. is presented, and the Newton-Raphson iterative algorithm is developed to obtain the displacements of the…
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Multi-objective Optimization of the PMS Based on Non-dominated Sorting Genetic Algorithm II

Ebco Inc-Peijun Xu
Huazhong University of Science and Tech-Yongfu Chen, Zhengfei Tang, Yunqing Zhang
Published 2015-04-14 by SAE International in United States
In order to reasonably match the variable stiffness and location of the Powertrain Mounting System (PMS) and optimize the ride comfort of commercial vehicle, a thirteen degrees of freedom (DOF) model of a commercial vehicle was established in Adams/view. Specially, the support rod installed on the upside of the transmission case was modeled as a flexible body.The vibration isolation provided by the PMS was evaluated in three aspects: the energy decoupling of the powertrain, the response force of the mount and the displacement of the powertrain. The energy decoupling ratio, the force RMS of the mount when force excitation was applied on the powertrain and the displacement of the powertrain Center of Gravity (C.G) when displacement excitation was applied on the vehicle chassis were selected as the optimal target. Adams and MATLAB were integrated into the optimization software iSIGHT to optimize the PMS. NSGA-II is used to obtain some Pareto-optimal solutions of PMS. Finally, a “performance function” is introduced to get the result of optimization.
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Frequency-Dependent Hydraulic Engine Mount with Five-Parameters Fractional Derivative Model in Vehicle model

Can Tao, Hengjia Zhu
Ebco Inc-Peijun Xu
Published 2015-04-14 by SAE International in United States
Hydraulic Engine Mount (HEM) is widely used in vehicle Powertrain Mounting System (PMS) for vibration isolation. The dynamic performances of an HEM are strongly frequency dependent. A Five-Parameters Fractional Derivative model is used to describe the dynamic properties of an HEM. A 1/4 car model is applied to evaluate the effect of frequency-dependent dynamic stiffness which using measured data of a typical hydraulic engine mount. The excitations from engine and road are considered in the simulation. The generalized- α method is presented to solve the vehicle model with five-parameter fractional derivative model.
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Optimal Seat Dynamic Parameters Determination for Minimizing Virtual Driver's Fatigue

Cummins Filtration, Inc-Prasad Kumbhar
Ebco Inc.-Peijun Xu
Published 2014-04-01 by SAE International in United States
In vehicle driving environment, the driver is subjected to the vibrations in horizontal, vertical, and fore-aft directions. The human body is very much sensitive to whole body vibration and this vibration transmission to the body depends upon various factors including road irregularities, vehicle suspension, vehicle dynamics, tires, seat design and the human body's properties. The seat design plays a vital role in the vibration isolation as it is directly in contact with human body. Vibration isolation properties of a seat depend upon its dynamic parameters which include spring stiffness and damping of seat suspension and cushion. In this paper, an optimization-based method is used to determine the optimal seat dynamic parameters for seat suspension, and cushion based on minimizing occupant's body fatigue (occupant body absorbed power). A 14-degree of freedom (DOF) multibody biodynamic human model in 2D is selected from literature to assess three types of seat arrangements. The human model has total mass of 71.32 kg with 5 body segments. Backrest support and feet contact with the vehicle floor are included in this model.…
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Evaluation of Human Body Response for Different Vehicle Seats Using a Multibody Biodynamic Model

Ebco Inc-Peijun Xu
Texas Tech University-Prasad Kumbhar, James Yang
Published 2013-04-08 by SAE International in United States
A valid human biodynamic model is very useful for studying the human body's response to whole body vibration. Whole body vibration is one of the important factors in the study of vehicle ride comfort. The environmental vibrations are transferred to the human body through floor and seat. Seated posture is the most commonly used position in automobiles. Therefore, studying the human body response in a seated position has attracted a lot of attention. Because the human body is in direct contact with the seat, its design plays a very important role in vibration transmission. In seat design, two important components are seat suspension and cushion. The mechanical properties of these components are stiffness, damping and mass. These properties can be changed by adjusting cushion material and seat suspension linkages. In this paper, three types of seat models are used. The first one is a hard seat. The second one has only cushion, and the third one is called an isolated seat which has seat suspension and cushion. For evaluating responses, one linear 14-degree of freedom…
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