Design and analysis of a cross car frame. Proposal of a three-level appraisal methodology

Abstract

This paper analyses the structural design process of a Cross Car frame. Existing international and national technical regulations were analysed. The analysis of the regulatory guidelines led to the conclusion that the design only includes geometric or material restrictions at the international level. There are other more demanding national regulations (Spanish, for instance) that include structural verifications through static calculations for unidirectional actions (vertical, longitudinal or lateral). The main contribution of this paper is a novel three-level appraisal and a proposed redesign methodology. At the first level, a geometric and material verification is carried out. The second level involves the verification under unidirectional static actions. The third level entails a dynamic verification of three-dimensional combined actions. The load case is obtained from the computer multibody dynamics simulation of the full vehicle assembly in the worst case of driving conditions on circuits. This methodology is a far more detailed tool than traditional design processes. The use of this methodology allows for design optimisation, including all the effects of powertrain, brakes, suspension, steering and driver.