Structural Health Monitoring in Smart Structures Using Lamb Waves Approaches

Nowadays there is great interest in structural damage detection using nondestructive tests. Once the failure is identified, as for instance a crack, it is possible to plan the next step based on a predictive maintenance program. There are several different approaches that can be used to obtain information about the existence, location and extension of the fault in mechanical systems by non destructive tests. This paper presents a technique for structural health monitoring (SHM) based on Lamb waves approach using piezoelectric material as actuators and sensors. Lamb waves are a form of elastic perturbation that remains guided between two parallel free surfaces, such as the upper and lower surfaces of a plate, beam or shell. Lamb waves are formed when the actuator excites the surface of the structure with a pulse after receiving a signal. In this context, a flexible plate using three PZT actuators and three PZT sensors was used to make the configuration of the Lamb waves approach. The aluminum plate was represented by a model of second order written in modal coordinates. Structural damages were simulated through reduction of the stiffness in one element. The results showed with clarity the location of the simulated damage; so, proving the viability of the presented methodology.