Research On Magnetostrictive Sensor For Structural Health Monitoring Of Plates

Guided wave inspection is a new emerging technology for rapidly assessing the structural damage in structural health monitoring (SHM). Most currently available guided wave sensors are based on piezoelectricity. Recently, a magnetostrictive guided wave sensor has received much attention because of several advantages such as potential non-contact detection and cost-effectiveness. In this work, the development of a magnetostrictive sensor for generating and detecting guided waves in a non-ferromagnetic plate is described. Stress waves propagating in a plate are firstly modeled and the dispersion relations of the waves are established, which settle the theory base for the sensor design. Analyzing the magnetostriction phenomenon based on the microstructure of the ferromagnetic material is employed to educe the sensor design which can transmitter and receive acoustic stress waves in a non-ferromagnetic plate. Wavelet transform is applied to the wave signals actuated and sensed by the sensor in the time-frequency domain to extract the characteristic information such as time arrival to measure the actual wave group velocities propagating in the plate. Comparing the calculated velocity with the theoretical velocity, the mode of the wave can be identified and the feasibility of the sensor is proved. Then the proposed magnetostrictive sensor is applied to identify the location of the damage in an aluminum plate. Finally, optimum design of the sensor is determined using ANSYS program to improve the sensor performance. The feasibility and effectiveness of the proposed magnetostrictive sensor is demonstrated by experimental studies.