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This work presents a methodology to take into account the effect of tire lifting in the numerical simulation of a commercial vehicle b-train. Firt, the basic equations of the vertical dynamics are showed, followed by the modifications suggested to be included into an existing numerical model of the vehicle (which does not consider the effect). Then, the use of the contact function of commercial software is explained for the tire lifting situation. A study is carried out for the simplified problem of a single wheel running on idealized surfaces. Once the correctness of the approach was asserted, the road obstacle benchmark was used to compare the results of both approaches in a full vehicle numerical simulation. The numerical results obtained with the inclusion of the tire/road separation agreed favorably to the available experimental results, what was demonstrated with graphical comparisons.

Transient dynamic analysis of vehicles riding pavements has became a reliable and important tool - whenever well carried out, in the durability and fatigue life evaluation of mechanical sub-components. Since a given vehicle or accessory is designed to operate on distinct types of terrain/roads, a detailed knowledge of these excitations is necessary for a realistic characterization of its effects over the structural parts. The most common form to obtain terrain profile is throughout profilometers installed on special vehicles. The amplitude vs. time signature of any terrain could then be used directly as the excitation applied to dynamic models, but this would restrict the analysis only to those terrains already measured and catalogued. The objective of the present work is to revist the generation of power spectrum density (PSD) functions aiming their usage as excitation on numerical dynamic models of vehicles.

The present paper shows some of the results obtained for service simulation and structural analysis of a small size vehicle with tubular structure. The results are presented after the successful use of the presented methodology in a practical case. All simulations in time domain were carried out by computer programs, which used terrain profiles compatible to the purpose of the vehicle. The dynamic loads obtained were applied to finite element models, allowing the evaluation of nominal stress concentration factors, necessary for reability evaluation. The proposed methodology showed to be quite effective, allow the evaluation of security factors in critical points and can be easily extended to general automotive structural elements.