Simplified models for passive safety engineering 2001-06-0223

In order to reduce delays of development of new vehicles, PSA has been using since 1998 a strategy based on sharing conception into several and hierarchical steps (V cycle). At the very beginning of a project, when only a few information are known, classical (and complex) FE models are replaced by simplified models, composed of sets of springs and loads elements containing properties (flexion, compression, shear) equivalent to complex FE pieces.

Up to now, these simplified models are created using FE models of vehicle with approximately same architecture. Sets of spring elements and properties are adjusted in order to reproduce FE model behavior. When simplified models behavior is judged representative of the physics, they can be used for conducting many investigations not only for studying a wide range of design parameters but also for evaluating the robustness of a specific design. The results permit to write technical specifications, for design departments, which in fact build the car pieces.

Using simplified models reduces delays of building numerical models (by a factor of five) and divides by 100 solving delays. It makes easier modelling modifications (a day instead of a week).

Finally, simplified models improve efficiency of crash simulation engineers by diminishing modelling time, by increasing the numbers of iterations and permitting a better understanding of the physics.

In the future, the aim of this method is to build simplified and classical FE models by using directly the CAD parts with additional physical properties in order to dispose automatically of a model which complexity depends on the available CAD data.