Investigation on Selection of Optimal Mother Wavelet in Mode Shape based Damage Detection Exercise

Abstract

The materials of the structures in use are always subjected to degradation in its characteristics over the period of time. The reduction in stiffness is always associated with such degradation. The analysis of vibration response of such materials with appropriate signal processing techniques has always led to the solution of damage identification exercises. The aim of the paper is to evaluate the performance of mode shape based technique along with wavelet transform through simulated model of structure- a cantilever, in damage identification exercise. A small transverse cut of wire thickness is introduced in cantilever beam. Depth of wire cut is varied to intensify the damage at various locations. Number of flexural modes are extracted from finite element modal analysis. Spatial continuous wavelet analysis is carried on number of modes. Effectiveness of different biorthogonal and reverse biorthogonal mother wavelets is studied to investigate the efficacy of the method. The proper selection of analysing mother wavelet influences the desired information extraction and its amplification process. The most suitable mother wavelet is recommended considering the nature of variation of wavelet coefficients.