Analyses of the effect of hardening on components of a seat structure for automotive application

Today, during the homologation phase of components for automotive application numerous physical tests are performed to verify compliance with the regulations. Building FEM models to study the behavior of the assembly before performing physical tests is useful to reduce both over-design and the number of prototypes tested to be compliant with regulations. One thing that should always be taken into account when assembling the model, to obtain a better correlation with the physical tests, is the modification in the mechanical properties of the componentsdue to the production techniques adopted to realize them. The purpose of this theses is, therefore, to investigate the differences seen in seat testing between FEM models and physical tests since the latter ones seems to always perform better than predicted by the FEM model, for what concern the metal components. It has been hypothesized that the differences might be caused by the increasing in mechanical properties that arise including in a model the effects of the hardening induced with cold stamping. At first the model of the whole seat has been prepared and then a rear crash with a 95th percentile dummy has been performed. The plastic strains were investigated to select on which component the stamping analyses should have been performed. After having performed the stamping analyses, two tests on the single component have been carried out to underline the increased mechanical properties of the hardened component with respect to the original one. Finally the rear crash with a 95th percentile dummy was performed again this time with the hardened component. For each test the differences between hardened and not hardened component will be investigated through the study of the differences in the plastic strain and the displacements.