Modeling of Lamb Waves and Application to Crack Identification

The objective of this study is to model Lamb waves generation and sensing for application to crack identification in engineering structures. Three topics were analyzed numerically using multiphysics finite element analysis. Initially, different types of Lamb wave generation techniques were investigated. A comparison between modeling the sinusoidal application of horizontal force (or displacement) as input and modeling the piezoelectric response of an actuator subjected to sinusoidal voltage input was performed. Secondly, the effects of a crack (disbond) between a piezoelectric wafer and the structure were analyzed, both for the piezoelectric actuator that generates the waves and for the sensor that measures the response. Finally, the appropriate fidelity of modeling a structural crack was investigated. In particular, the use of contact elements was evaluated on their role in the accurate prediction of the wave scattering from cracks or defects inside the structure.