PROPAGATION OF LAMB WAVES IN COMPOSITE LAMINATES

Abstract

Composite materials are extensively used in various applications due to its high strength to weight and stiffness to weight ratio. But these. suffer from material deterioration when subjected to adverse mechanical or environmental conditions. Hence a periodic Non destructive inspection of composite material components is - needed. Most commonly used Non-destructive Techniques for composites is the ultrasonic testing method. Since the composite structures are normally in the form of plates or shells, a systematic study of the propagation of Lamb waves in composite plates assumes considerable significance. In the present work the basic formulation for Lamb wave propagation in an isotropic plate is presented. The transfer matrix approach is adapted to obtain the dispersion curves for an N-layer plate. Typical curves for an isotropic N-layer plate are presented. The variation in the dispersion curve with change in stacking sequence of the layers and the material parameters of the layers has been studied. The results obtained may be effectively used to characterize all the material stiffness parameters. Thorough material characterization may further be used to quantify the overall damage in the isotropic plate