Extraction of Static Car Body Stiffness from Dynamic Measurements

Jan Deleener; Peter Mas; Luc Cremers; Jeffrey Poland

doi:10.4271/2010-01-0228

This paper describes a practical approach to extract the global static stiffness of a body in white (BIW) from dynamic measurements in free-free conditions. Based on a limited set of measured frequency response functions (FRF), the torsional and bending stiffness values are calculated using an FRF based substructuring approach in combination with inverse force identification.

A second approach consists of a modal approach whereby the static car body stiffness is deduced from a full free-free modal identification including residual stiffness estimation at the clamping and load positions. As an extra important result this approach allows for evaluating the modal contribution of the flexible car body modes to the global static stiffness values.

The methods have been extensively investigated using finite element modeling data and verified on a series of body in white measurements. The results are compared with the conventional static test bench measurements and have shown to deliver robust results, with similar accuracy, in a more efficient way in terms of testing time and costs.

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Extraction of Static Car Body Stiffness from Dynamic Measurements 2010-01-0228

SAE MOBILUS