Validation of Automatic Modal Parameter Estimator on a Car Body-in-White

Noise, vibration and harshness (NVH) problems are critical issues to be tackled by automotive industry to ensure comfort of people. The key role of this problem is played by the susceptibility of the structure to vibrations. Therefore, design values such as the modal parameters (i.e. eigenfrequencies, damping ratios, mode shapes and modal scaling factors) are essential and their experimental validation is of high interest. At this purpose, both Experimental and Operational Modal analysis (EMA and OMA) represent a powerful approach. Previous works have investigated and implemented a completely automated OMA technique for continuously tracking the modes of machines under normal operating conditions. In this work the automatic modal parameter estimator is used to perform automated experimental modal analysis on data acquired from a car body-in-white excited by means of multiple shakers. Fully automated modal analysis is performed with special focus on damping value and mode shape validation. The results obtained with the manual and automatic modal parameter estimators are compared in order to show the validity and performance of the implemented method. Modal parameters estimation is based on the state-of-the-art pLSCF algorithm. To make it suitable for continuous analysis, the algorithm is improved by eliminating all the required human interactions.