The Finite Element Simulation of Lamb Wave Propagation in a Cracked Structure with Coupled Filed Elements

Abstract

Crack detection by Piezoelectric Wafer Active Sensors (PWAS) is one of the emerging methods of Non-destructive Evaluation (NDE). These sensors can assess the health state of the structure in far filed through the analyzing the high frequency Lamb wave propagation. As PWAS is the essential part of this method, simulation and modeling of these sensors and their interaction with the host structure, strongly affect the accuracy of results. In this study, unlike the previous works, in which some certain areas of the host structure were considered as a sensor and actuator, the direct simulation of electro-mechanical interaction of the PWAS and the host structure is modeled among modeling the PWAS with a FEM coupled-field element. After verification of the FEM analysis with theoretical group velocity of S0 mode, capability of the S0 mode in crack detection was examined. Different length and angles of the crack in an aluminum plate modeled. The crack growth effect was defined among a damage index by using the strain energy magnitude that received by sensor localized behind the crack. The result showed that transmitted energy from the cracks decreases as the crack length increases. In addition, as the angle crack to the sensor increases, the ability of sensor to crack detection will increase.