Structural integrity analysis with piezoelectric patches

Structural integrity analysis, like detection of cracks and delaminations, is an important issue in structural health monitoring of metallic and composite structures. This paper focus on the possibility of using small piezoelectric patches attached to or embedded into the structure being monitored and their capability for damage detection. A brief theoretical description of the method used is introduced, based on the generation of strain waves inside the material and the influence of existing damage in their propagation, analysed both in time and frequency domain. An electronic device was built in order to be able to use a single patch for both, generating and detecting the waves. The results obtained in our laboratory on an aluminium plate with growing cracks are given and analyzed.