Fatigue damage assessment of a car body-in-white using a frequency-domain approach

This work presents an application of a frequency-domain methodology developed for the fatigue damage and service life assessment of mechanical components under multiaxial random loadings. The road-induced random loadings in a virtual laboratory bench test (four post test rig) are determined using an integrated MB/FE (Multi-Body/Finite Element) analysis. A method (i.e. the variance method) based on the statistics of the observed multiaxial loadings is used to determine the critical direction. The shear stress resolved on the critical direction is then assumed as the reference loading for the subsequent fatigue analysis. A frequency-domain approach recently proposed in the literature (i.e. the non-Gaussian TB method), capable to include the load non-normality into the fatigue assessment procedure, is used to estimate the loading spectrum. A comparison between the observed and the estimated loading spectrum, extrapolated from short to longer time (e.g. the entire vehicle service life), is shown. The presented results show how the proposed methodology could be a very useful tool for the reliable and quick analysis of components under multiaxial random loadings.