Structural Health Monitoring in Composite Materials Using Lamb Wave Methods

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in-situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasi-isotropic graphite/epoxy thin coupons and sandwich beams containing representative damage modes, including delamination, transverse ply cracks and through-holes. Optimization experiments provided a procedure capable of easily and accurately determining the presence of damage by monitoring the transmitted waves with piezoceramic sensors (PZT). Lamb wave techniques have been proven to provide more information about damage type, severity and location than previously tested methods, and may prove suitable for structural health monitoring applications since they travel long distances and can be applied with conformable piezoelectric actuators and sensors that require little power.