Crack detection in a beam using PZT sensors

This paper proposes a method to detect the size and location of an edge-normal crack in a beam-like component by fixing discrete PZT patches at its top and bottom edges. Both theoretical and experimental results are presented. The beam geometry conforms to that of a simply supported beam. Theoretical studies were carried out using the boundary element method (BEM). Variations in the voltage drop in the patches with various crack sizes and positions were obtained theoretically. These results were fitted into a surface. Some of these results were verified by experiments. The inverse problem was also solved. Both the crack size and position were predicted from the voltage drop recorded experimentally by a pair of PZT patches. The maximum errors in the prediction were 9.33% and 4.95% respectively. Cracks as small as 3% of the beam depth can be detected. The response of a sensor is only significant when the distance between a crack and a patch along the edge is approximately less than the depth of the beam. Based on studies with distributed patches, a possible scheme for detecting a crack located anywhere over the entire span of a beam is presented.