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.