Inference of Random Excitations from Contactless Vibration Measurements on a Panel or Membrane Using the Virtual Fields Method

Abstract

This paper aims at identifying random excitations acting on thin, plane structures from their measured vibration response. For random pressure fields such as the diffuse acoustic field (DAF) and turbulent boundary layer (TBL), two quantities of interest are to be determined, namely the wall pressure auto-spectral and cross-spectral density functions. These quantities are reconstructed using the virtual fields method, an identification technique based on the principle of virtual work. Numerical identification results for the auto-spectral and cross-spectral density functions are presented for both a plate and a membrane submitted to DAF and TBL excitations. Experimental identification results are then presented for the pressure auto-spectrum applied to an aluminum panel under DAF excitation from vibration response measurements that were obtained using deflectometry, a full-field optical measurement technique.