الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Vehicle dynamics aspects include the suspension system which should maintain good ride quality and road holding performance against the road irregularities especially in the case of high driving speeds. In this study, several models of air spring suspension systems are represented; two different passive air spring models (classic air spring and dynamic air spring), active air spring models based on the Proportional-Integral-Differential, Linear Quadratic Regulator controller, active limited bandwidth and semi-active suspension system models. The semi-active suspension system is presented focusing on the performance analysis of a switchable damper with four damping modes integrated to an air spring by controlling the on-off statuses of two solenoid valves which makes its damping adjustment more efficient and more reliable. Two degrees of freedom mathematical model was used and implemented in MATLAB/Simulink platform. The ride quality and road holding responses were evaluated considering a vehicle speed of 20 m/s and time domain random road input. The particle swarm optimization was used in a parametric investigation of an air spring suspension system for different objective functions which mainly are minimizing body acceleration, suspension deflection and dynamic tire load. The theoretical results indicate that all of these systems offer worthwhile improvements over the traditional passive, the Linear Quadratic Regulator controller gives a better behavior in ride comfort and road holding over the optimized air spring suspension system, Proportional-Integral-Differential Controller, semi-active and limited bandwidth suspension systems in terms of time and frequency domain analysis. The important concluding remarks obtained throughout the simulation results of the proposed systems indicated that the improvements of the body acceleration RMS over the passive air suspension system are 47%, 45%, 39.9% and 35.8% for LQR Controller, Semi-active, Limited Bandwidth, and PID Controller, respectively. On the other hand, the improvements of the suspension deflection RMS over the passive air spring systems are 6.5%, 0.1%, 13.5%, and 9.7%. Finally, in terms of the dynamic tire load, the improvements compared with the passive air spring suspension are 7.7%, 6.9% and 11.5% and 1.3% respectively.
Thereafter, a parametric sensitivity analysis was carried out to find the sensitivity change of the dynamic responses against the air spring parameters in which the results are evaluated in terms of RMS values body acceleration, suspension deflection, and dynamic tire load. Furthermore, the damping and stiffness characteristics of the of the air spring suspension system were measured using a characteristic test rig with a sine wave excitation force. Experimental results of the air suspension systems are investigated in which a quarter car test rig built in Vehicle Dynamic Laboratory, Automotive and Tractor Eng. Dept., Faculty of Eng., Minia University. The validation process was thus performed to compare the developed models with the traditional passive suspension, air spring suspension and semi-active suspension against the experimental setup. The results indicated that the theoretical models are always more optimistic than the experimental results. Then the experimental work is extended to include the dynamic performance represented by the ride comfort and road handling when the air suspension system was used under different air spring pressures based on a quarter vehicle test rig. Moreover, the dynamic performances of the semi-active air suspension system with multi-mode damping damper were measured considering the result in terms of the time history and power spectral densities of body acceleration, suspension deflection and dynamic tire load.