Impact identification on a sandwich plate from wave propagation responses

This study investigates the use of an impact detection algorithm to locate a potentially damaging impact on an orthotropic plate by detecting the stress waves generated by such an event. The proposed algorithm was tested experimentally on a sandwich plate by using ultrasonic signals. The arrival times of stress waves at different frequencies at the sensor locations were determined by analyzing the recorded signals using the wavelet transforms. The stress wave propagation phenomenon was characterized by measuring the propagation speeds along different directions. This data along with the sensor co-ordinates were input into the impact detection algorithm, which uses the difference in time of flight to the sensors and trigonometric identities to locate impact source locations. The accuracy of the method was demonstrated by the close agreement observed between the estimated locations for the three impact locations studied with the actual locations of the impact loads applied. In particular, maximum error in the estimation of the co-ordinates of the impact location was less than 9% for all different types of loading considered.