Limits of applicability of the standard method for estimating the torsional rigidity of spatial frames of buggy vehicle

Abstract

The article provides an assessment of the limits of applicability of the standard methodology for estimating the torsional rigidity of spatial rod-bearing systems of automobiles. Torsional stiffness, as shown by numerous studies and practices, is one of the most important indicators of the carrying capacity of vehicle bodies (frames) of all types of vehicles - including such highly specialized ones as buggy. The authors show on the example of the bearing structure of an off-road vehicle of the “buggy” class that the general application approach to the assessment of the torsional rigidity of the bearing systems using torsion deflection stumbles upon limitations when it comes to spatial frames of complex construction. These restrictions are dictated by the difference in stiffness between design zones (zones should be understood as the floor area, the waist area and the roof area), which is reflected in the significantly different distribution of displacements in them. As a result, it becomes impossible to unequivocally give an opinion on the torsional rigidity of the frame using torsion deflection, since it is impossible to select a reference point in any of the zones (or the entire zone) to adequately describe the torsional rigidity of the whole structure (or a separate substructure). In this regard, the authors proposed the limits of applicability of the traditional method for estimating the torsional stiffness of a spatial core structure, and also proposed a method for overcoming these difficulties encountered when trying to assess the torsional stiffness of the supporting structure. The object of the research is a typical spatial frame of an all-terrain automobile of the D2 class buggy.