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Role of road roughness in vehicle ride

In: Transportation Research Board, 60th annual meeting, 12-16 Jan 1981, Washington, D.C.

Authors: T. D. Gillespie, M. Sayers

This paper describes the gross mechanics of motor vehicle ride vibrations to acquaint the highway engineer with the role played by road roughness. The acceleration spectrum observed on a typical passenger car is compared against available measures of human vibration tolerance to illustrate the frequency range of general interest. The characteristics of road roughness are presented in terms of both the elevation spectral density and the equivalent acceleration excitation to the vehicle. The mechanisms of ride isolation achieved through the suspension systems of motor vehicles are illustrated by attenuation of the response gain at high frequency. Examples are given to show effects of mass, suspension, and tire properties. Additional attenuation effects derive from wheelbase filtering and tire envelopment, in the case of commercial trucks, the compromises that occur in the ride isolation as a result of suspension friction and low frequency structural resonances are illustrated.