Dynamic Response of Tractor-Semitrailer Vehicle to Random Inputs

This paper is concerned with the dynamic analysis of vehicle-road using the theory of stochastic processes. The tractor-semitrailer vehicle is treated as a discrete, linear, time-invariant dynamic system subjected to a stationary random input from the road surface. The vehicle model, including primary and secondary suspension systems, and subject to both heave and pitch motions, has six degrees of freedom. A representation of random roughness of the road is given, frequency domain analysis is applied, and a parametric study is presented. The theoretical investigation described in this paper represents an attempt to obtain a better understanding of the significant parameters of vehicle construction and road characteristics involved in (a) the vibrations transmitted from the roadbed to the tractor-semitrailer vehicle, (b) the dynamic forces at the tyre-road interface. The results of the computer analysis of vehicle and road are presented in two forms; the amplitude spectra and the root mean square amplitudes which are used to predict vehicle ride quality and evaluate the design concepts. (Author/TRRL)