Experimental determination of mode shapes of a plate using speaker as excitation device

Abstract

Experimental modal analysis is usually carried out in two methods, namely impact hammer method and shaker method. The limitation of both the methods is determination of mode shapes. Of course, the mode shapes are obtained using FFT analyser which is costly software. In this paper, however an attempt is made to determine the mode shapes of a plate experimentally using a speaker as excitation device. An experimental setup was prepared using a speaker to excite a plate at its central portion. An aluminium plate was mounted at its central portion and excited. Dust particles were sprinkled over the plate and when the excitation frequency matches the natural frequencies, the corresponding mode shape of the plate was obtained. The numerical modal analysis was carried out for the plate with proper boundary conditions using finite element analysis package ANSYS Workbench. The mode shapes obtained numerically and experimentally were compared and observed to be in good agreement.