Experimental evaluation of modal damping in automotive components with different constraint conditions

The selection of reliable damping values for mechanical components of complex shape is very difficult from a theoretical point of view, above all in the case of complex constraint conditions. This work presents an example of experimental procedure for estimating the modal damping in a family of mechanical components. An Experimental Modal Analysis (EMA) program has been carried out on different types of brackets used on diesel engines, and in different constraint conditions with the aim of collecting the damping values in a database. In particular, the EMA has been carried out on brackets in the freely-supported condition and in the clamped condition actually used in the engine, highlighting the variations in modal damping with the different constraint conditions. The results of the experimental measurements have been processed with different modal analysis algorithms in order to increase the robustness of the solution. The resulting damping plots represent very useful data in the field of numerical analysis.