The Time Domain Simulation of Non-Stationary Road Roughness

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.

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

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041988187
Author(s):  
Bin Yu ◽  
Zhice Wang ◽  
Dayou Zhu ◽  
Guoye Wang ◽  
Dongxin Xu ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Ride Comfort ◽  
Response Characteristic ◽  
Power Spectrum Density ◽  
Damping Coefficient ◽  
Road Vehicles ◽  
Road Vehicle ◽  
Road Roughness ◽  
Vibration Model ◽  
Spectrum Density

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.

Research on Modal Identification Method of Pre-Stressed Concrete Bridge

2013 ◽  
Vol 405-408 ◽  
pp. 1651-1654
Author(s):  
Hao Jiang ◽  
Guang Wei Meng ◽  
Hai Kuo Zhang
Keyword(s):  
Power Spectrum ◽  
3D Model ◽  
Time History ◽  
Power Spectrum Density ◽  
Modal Identification ◽  
Average Error ◽  
Concrete Bridge ◽  
Modal Parameter ◽  
Density Peak ◽  
Spectrum Density

To study validity of power spectrum density peak method which be used to identified modal parameter of concrete bridge under ambient excitation, number simulation of one Pre-stressed concrete bridge is carried out.3D model of the bridge is established by FEM software , FEM analysis and time-history analysis of 3D model of PC continuous beam bridge are carried out.During the simulation,practical factors such as acceleration measuring and white noise are taken into account. In the only case of the output signal modal parameter of bridge can be identified. Six-order modal parameters of the structure are identified by the number simulation which the average error is less than 5%. It is revealed that power spectrum density peak method is suitable for bridges monitoring and diagnosis, with important practical engineering application value.

An Improved Road Roughness Simulation Method Based on Trigonometric Series Method

2014 ◽  
Vol 513-517 ◽  
pp. 3277-3282 ◽  
Author(s):  
Xi Wang ◽  
Jiang Bo Zhao ◽  
Jun Zheng Wang
Keyword(s):  
Trigonometric Series ◽  
Ride Comfort ◽  
Minimum Energy ◽  
Simulation Method ◽  
The Road ◽  
Road Roughness ◽  
Spectrum Density ◽  
Random Frequency ◽  
Poor Convergence ◽  
Road Data

Accurate road data is critical to vehicle ride comfort research. Trigonometric series (TS) method is widely used in road roughness construction, but the accuracy of the road data in time domain is not high and the power spectrum density (PSD) exits poor convergence problem. To solve the above problems, this paper has made two improvements: generate random frequency in each band using the local PSD function, optimize phase angle using the principle of minimum energy. The simulation results show that the improved method has higher precise and better convergence of PSD.

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

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.

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

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

Stationary and Transient Response of Cylindrical Shells Under Random Excitation

1988 ◽  
Vol 110 (2) ◽  
pp. 205-209
Author(s):  
A. V. Singh
Keyword(s):  
Transient Response ◽  
Random Vibration ◽  
Time History ◽  
Wide Band ◽  
Random Excitation ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
History Of ◽  
The Mean ◽  
Random Vibration Analysis

This paper presents the random vibration analysis of a simply supported cylindrical shell under a ring load which is uniform around the circumference. The time history of the excitation is assumed to be a stationary wide-band random process. The finite element method and the condition of symmetry along the length of the cylinder are used to calculate the natural frequencies and associated mode shapes. Maximum values of the mean square displacements and velocities occur at the point of application of the load. It is seen that the transient response of the shell under wide band stationary excitation is nonstationary in the initial stages and approaches the stationary solution for large value of time.

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

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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