Simulation of lamb wave in composite for structural health monitoring

With the technological advancement in materials engineering, composite material has become increasingly popular for use in many industries. This leads to a need for a Structural Health Monitoring (SHM) system for composite materials. Among various SHM methods, the guided wave emerges to be a promising technology with its advantages of speed in inspection and being active in monitoring. This report presents studies on guided wave propagation using numerical simulation carried out by finite element software PZFlex. Several 2-dimensional (2D) simulations have been carried out on S¬0 and A0 Lamb wave propagation in Carbon Fiber Reinforced Plastics (CFRP), as well as piezoelectric crystal actuated Lamb wave. Good agreement has been found by comparing with theoretical and experimental results. 3-dimensional (3D) CFRP plates are modeled to study the amplitude attenuation of Lamb waves. The effect of different ply orientations: unidirectional, cross-ply and angle-ply, and different excitation areas are investigated. The rate of attenuation with units of dB/mm is obtained for each type of CFRP plate. The attenuation rate is subsequently applied to several practical structures and it is found that it is feasible to use inspect large-scale structure such as wind turbine blade and aircraft wing. Mode conversion method to locate defect is investigated with algebraic formulation, and verified by 2D and 3D simulations. The method is promising in determining the vertical notch location with the correct input of wave velocity. Further investigation is required in order to apply the method to large-scale structures with different geometry.Bachelor of Engineering (Aerospace Engineering