An approach to multidimensional equivalent fatigue loadings

In the automotive industry, temporal, financial and human constraints require continuous improvements in the design process of new vehicles, by delivering relevant specifications and providing reliability and robustness in design. In order to analyze factors like behaviors of drivers and types of roads and guarantee the reliability of car components, measurements of forces from wheels are stored when the vehicle is tested on tracks and used by customers. The measurements represent the time history of multi-dimensional forces on the four wheels in the longitudinal, vertical and transversal directions. They are applied on structures (suspensions or motoring for instance) during the design life of the vehicles. The context of this paper is the fatigue analysis of multi-input loadings. The study will be focused on random and possibly correlated multi-input processes, representing multidimensional forces. The goal of this paper is to present an approach to generate simple mu lti-input loadings equivalent to measurements In terms of damage. The simple loadings have to be equivalent for any arbitrary structure, satisfying the reliability requirements imposed by the car manufacturer.