Optimization and testing of suspension system of electric mini off-road vehicles

Mini vehicles with a small wheelbase are extremely sensitive to road roughness. The aim of this study is to explore the influence of road information on ride comfort and enhance the ride comfort of mini vehicles. According to the 5-degree-of-freedom vibration model of an electric mini off-road vehicle, the partial differential matrix equation of system motion is established using the Lagrange method, and the frequency response characteristic of the system is analyzed. The input matrix of pavement unevenness is obtained by considering the mutual power spectrum density between front and rear wheels. Road surface roughness information is obtained using an instrument for measuring road roughness. A comprehensive objective function and a constraint condition are established for comfort and safety. Based on the parameters obtained through the optimum design of a 1/4 vehicle model, the optimized stiffness and damping coefficient of suspension are obtained using a MATLAB optimization program. The law of the vibration performance of off-road vehicles with respect to suspension stiffness and the damping coefficient is obtained through the analysis of optimized results. A driving simulation and a test are conducted on the electric mini off-road vehicle. The results show that the use of the measured pavement data as simulation input is closer to the actual situation and provides higher accuracy compared to the simulated pavement model. According to the optimization and test results, the parameters optimized by a 1/2 vehicle (5 degrees of freedom) vibration model are better than those optimized by the 1/4 vehicle vibration model. The optimization results confirm reduction in acceleration, acceleration power spectrum density, and the root mean square of the weighted acceleration of the seat. This shows that the electric mini off-road vehicle provides better ride comfortability after optimization.

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The Time Domain Simulation of Non-Stationary Road Roughness

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.423-426.1238 ◽

2013 ◽

Vol 423-426 ◽

pp. 1238-1242

Author(s):

Hao Wang ◽

Xiao Mei Shi

Keyword(s):

Power Spectrum ◽

Time Domain ◽

Ride Comfort ◽

Time History ◽

Random Excitation ◽

Power Spectrum Density ◽

The Road ◽

Road Roughness ◽

Spectrum Density ◽

History Of

The input of road roughness, which affects the ride comfort and the handling stability of vehicle, is the main excitation for the running vehicle. The time history of the road roughness was researched with the random phases, based on the stationary power spectrum density of the road roughness determined by the standards. Through the inverse Fourier transform, the random phases can be used to get the road roughness in time domain, together with the amplitude. Then, the time domain simulation of the non-stationary random excitation when the vehicle ran at the changing speed, would also be studied based on the random phases. It is proved that the random road excitation for the vehicle with the changing speed is stationary modulated evolution random excitation, and its power spectrum density is the stationary modulated evolutionary power spectrum density. And the numerical results for the time history of the non-stationary random inputs were also provided. The time history of the non-stationary random road can be used to evaluate the ride comfort of the vehicle which is running at the changing speed.

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Analysis of vehicle ride comfort applying a 2SPS+SR parallel seat mechanism

Noise & Vibration Worldwide ◽

10.1177/0957456521999835 ◽

2021 ◽

pp. 095745652199983

Author(s):

Bijuan Yan ◽

Jie Zhang

Keyword(s):

Power Spectrum ◽

Root Mean Square ◽

Ride Comfort ◽

Three Dimensional ◽

Power Spectrum Density ◽

Mean Square ◽

Vibration Level ◽

Theoretical Support ◽

Motion State ◽

Spectrum Density

The violent vibration may cause discomfort to the driver and operation instability in different directions including fore-aft, lateral, and vertical when construction vehicles are driven or operated on off-roads. To improve ride comfort, a novel kind of 2SPS+SR parallel seat mechanism is proposed in this article. First, to verify the motion state of one translation and two rotations, the model of this new seat mechanism was built and analyzed using UG software. Furthermore, the acceleration and power spectrum density between the conventional seat and the 2SPS+SR parallel seat were compared in three directions of vertical, pitching, and rolling when the vehicle was driven on different three-dimensional roads. Then, the comparisons of the weighted vibration level and the root mean square of the total weighted acceleration on different roads were illustrated to denote the ride comfort of the construction vehicle. The results show that this 2SPS+SR parallel seat mechanism could improve the ride comfort of construction vehicles. The results will provide theoretical support for further research on the control of vehicle vibration.

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Orientation holes positioning of printed board based on LS-Power spectrum density algorithm

Traitement du signal ◽

10.3166/ts.35.277-288 ◽

2018 ◽

Vol 35 (3-4) ◽

pp. 277-288

Author(s):

Xiaxia ZENG ◽

Zhenhua SONG ◽

Wenzhong LIN ◽

Haibo LUO

Keyword(s):

Power Spectrum ◽

Power Spectrum Density ◽

Spectrum Density

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Random Response Analysis of a Large-Size Cooling Tower Subjected to the Stationary Earthquake Motion

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.423-426.1589 ◽

2013 ◽

Vol 423-426 ◽

pp. 1589-1593

Author(s):

Jia Ning Zhu ◽

Ya Zhou Xu ◽

Guo Liang Bai ◽

Rui Wen Li

Keyword(s):

Power Spectrum ◽

Random Vibration ◽

Cooling Tower ◽

Response Spectrum ◽

Power Spectrum Density ◽

Random Response ◽

Large Size ◽

Earthquake Motion ◽

Spectrum Density ◽

Random Vibration Theory

The response of a large-size cooling tower with 250m high subjected to the seismic action are investigated by both random vibration theory and response spectrum method. Shell element is taken to model the tower body, and beam element is used for the circular foundation and supporting columns. The earthquake motion input is a colored filtered white noise model and mode superposition method is adopted to analyze the random response of the large-size cooling tower. The paper presents the power spectrum density functions (PDF) and standard deviation of the displacement of the top and characteristic node, and the analysis results indicate that the results of the stationary random vibration theory and the response spectrum method are the same order of magnitude. The power spectrum density function of the bottom node stress is obviously bigger than the one at the top and the throat, and the random response of meridonal stress is dominated at the top. In addition, the peak frequency position of the power spectrum density function is different from the corresponding stress.

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