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A vehicle-human model for analysis of ride comfort predominated with vertical and pitch motions
Published in Maksym Spiryagin, Timothy Gordon, Colin Cole, Tim McSweeney, The Dynamics of Vehicles on Roads and Tracks, 2018
H. Zhou, Y. Qiu, R. Lot, J.D. Gao, J.S. Yang
For the pitch of the seat base, the model matched well with the measured data at frequency below 2 Hz (especially at the first resonance 1.25 Hz, Figure 5), but failed to predict the other two resonances as shown in the measured data. It appears that the resonances at 2.5 Hz and 3.75 Hz are harmonics of the primary resonance which may be related to the excitation of road irregularity. The predicted roll motion of the seat base showed a good agreement with the measured data at frequencies above 6 Hz but a large discrepancy existed below 2 Hz. It seems that the roll motion of the vehicle body at the very low frequency (below 2 Hz) was not sufficiently excited in the field test. It may be also because the 4-poster test data used in the model calibration did not contain sufficient information of roll motion of the vehicle. The correlation can be improved during the model calibration by also using 4-poster test data with out-of-phase excitations between the left and right wheels.
Sensitivity analysis and optimisation of suspension bushing using Taguchi method and grey relational analysis
Published in Vehicle System Dynamics, 2018
Sadegh Yarmohammadisatri, Mohammad Hasan Shojaeefard, Abolfazl Khalkhali, Soheil Goodarzian
In this paper, the ride and handling performances of Renault Logan car is investigated by experimental test. These tests are used to verify the simulation results obtained by ADAMS/CAR software. In order to investigate the stability and ride issue, comprehensive experiments such as constant radius test and double lane change tests are necessary. The ride comfort of the vehicle is evaluated in 4-poster test rig. In this case, two different sets of experimental tests have been done in one of the main Iranian automakers SAIPA. For the ride comfort test, the vehicle in 4-poster test rig is subjected to various types of road profiles. Different acceleration and displacement sensors were installed on the vehicle to record the results of road vibrations on the vehicle parts. In this experimental test, seven acceleration sensor and two displacement sensors have been used. Two of these accelerometers have been installed on the shock absorber of the rear wheel which determines the acceleration exerted to the rear sprung masses of the vehicle. The other two sensors are installed on the front shock absorbers of the vehicle. One of the accelerometer is mounted under the driver seat for detecting the accelerations which is inserted to the driver. Another one is placed in the approximate place of the vehicle centre of gravity. The schematic location of the accelerometers and their positions in Logan car are presented in Figure 1. By subjecting the wheels of Renault Logan to sine sweep road profiles in 4-poster test rig, natural frequencies of the vehicle are extracted in different directions (Figure 2). Input frequencies vary from 0.5 to 5 Hz with the rate of 0.1 Hz/s and displacement of each wheel is 6.25 mm. The pitch angular velocity in both time and frequency domain (Figure 2(a,b)), Vertical velocity in both time and frequency domain (Figure 2(c,d)) and Roll angular velocity in both time and frequency domain (Figure 2(e,f)) are obtained in 4-poster test.