Modal Parameters of Multiple-Disk Shaft System from Multiple Reference Impact Test

Abstract

The proposed work is intended for Experimental Modal Analysis (EMA) of a multi-disk shaft system to estimate its modal parameters, i.e., natural frequencies, damping ratios, and mode shapes. The considered system is excited by a roving impact hammer at a set of excitation points, and the vibration response is measured at a number of response points (taken as reference points) using piezoelectric accelerometers. The Frequency Response Function (FRF) matrix and the corresponding Impulse Response Function (IRF) matrix are estimated, which allows the detection and estimation of repeated or closely coupled modes, known to exist in the considered structure. The estimated FRF and IRF matrices are employed with both time and frequency domain algorithms to estimate the desired modal parameters. Modal frequencies are estimated from Finite Element analysis using ANSYS and compared with the experimentally obtained frequencies.