Dynamic Behavior of Three-wheeled Vehicle Under Random Road Characteristics Using FEM
In general three wheelers are one of the most popular city transport vehicles in the world and particularly in developing countries especially for short hauls. In the present work finite element model of three wheeled motor vehicle chassis has been developed using ANSYS software by taking into account the chassis longitudinal/cross members, the suspensions, the axles and the tires. Modal analysis is carried on the three wheeled motor vehicle chassis using Block Lanczo's technique to obtain the natural frequencies and mode shapes. Vertical dynamic response of the three wheeled motor vehicle chassis has been carried in the frequency domain by performing the spectrum analysis using ANSYS software. When the vehicle moving at 45 kmph on different Indian and International roads, and the response is obtained at four significant points i.e. at node 2 (rear part of the chassis sprung mass), at node 8 (passenger seat position), at node 657 (rear axle) and at node 34 (steering position). The response i.e. power spectral density of acceleration is compared between the Indian and International roads and different modes which affect the passenger comfort are also discussed using spectrum analysis. Parametric study has also been carried out using the finite element model to study the effect of various parameters and to find the optimum values both quantitatively and qualitatively, in the ride response of the vehicle. Finally based on the above analysis certain recommendations are made about manufacturer point of view.
Power Spectral Density Analysis of Vehicle Vibration Using the NASTRAN Computer Program
Frequency response and power spectral density analyses are implemented on the NASTRAN computer program for the purpose of assessing the vibratory response of automotive vehicles. A review of theoretical concepts related to the frequency domain techniques is presented, followed by a derivation of the equations of vertical motion for a linearly elastic automotive vehicle. Special emphasis is given to the discussion of random loading, and the cross-spectral density matrix for the terrain input to a four-wheel vehicle is derived. Example calculations are performed for a compact-size vehicle exposed to moderately severe road roughness.
The Laboratory Simulation of Vehicle Service Stress
A simulation technique which will enable the response of vehicle components or complete vehicles to be reproduced in the laboratory is presented. For the case of a complete four wheeled vehicle it is shown how synthesized random displacements, based on a knowledge of the road surface undulations, can be derived; it is demonstrated that the information necessary to derive these four signals can be obtained from the spectral density evaluated from a single traverse along the road. Comparison is made between vehicle response measured on the test track, and the response on the simulator under synthesized random displacements and point-by-point profile excitation.