EMA-FEA correlation and updating for nonlinear behaviour of an automotive heat-shield

Abstract

This paper focuses on the correlation between Experimental Modal Analysis (EMA) and Finite Element Analysis (FEA) of an automotive component where different parameters can affect the simplicity of a linear approach. The component is a heat-shield that covers the catalytic converter through rigid brackets and fasteners. Thermal refractory, viscous and vibration absorber material is interposed between two steel sheet layers. This filler material and the wafer-like structure of the shield are thought of being the main cause of nonlinear behaviour. Shaker tests with force-controlled sine sweep excitation are performed for obtaining linearised data on different force levels for the updating step on the model. In particular the system presents complex bending dynamics of the shield coupled to the entire structure. Due to the constraints and the added masses of instruments to measure it, veering phenomena are evinced. A One Factor At Time (OFAT) study on the numerical model is performed for tuning unknown parameters and build an effective and reliable model that could fit the experimental results. Several modelling techniques for the filler are considered to investigate its effect on the dynamic response and the sensitivity to the factors involved. Modal Assurance Criterion (MAC) and frequency comparisons are used for evaluating the discrepancies between model and experiment.