Lamb waves for the non-destructive inspection of monolithic and sandwich composite beams

The aim of the current study is to develop a cost and time effective inspection strategy for in-service health monitoring of composite structures. An experimental study is presented, that demonstrates the potential of low-frequency Lamb waves being used for the inspection of monolithic and sandwich composite beams. Small and unobtrusive piezoceramic patches are used to generate and capture flexural waves propagating through the structure at low frequencies. Multidirectional carbon fibre reinforced plastic beams of various lay ups are tested for the detection of matrix cracking, delaminations and broken fibres. The technique is also successfully applied to the damage inspection of composite sandwich beams.