Lap joint inspection using plate waves

The problems of guided waves propagating across a lap joint as well as reflected by the free edge of a semi-infinite plate with defects are investigated both theoretically and experimentally. The theoretical analysis is accomplished bg using a hybrid method called the global local finite element method. a bounded region enclosing the lap joint, or the free edge, is descritized and analyzed by the finite element method, and the Lamb wave modal expansion is used to represent the wave field outside this region. The experiments are performed by using the Fracture Wave Detector. The theoretical and experimental results are compared and show good agreement.