Combination of time reversal process and ultrasonic tomography approaches for baseline-free damage diagnosis

Lamb wave time reversal method is a new and promising baseline-free damage detection technique for structural health monitoring. With this method, damage can be detected without baseline data. In the paper an online damage detection and identification method is presented using time reversal Lamb waves method and ultrasonic tomography for damage diagnosis of composites. The principle and features of the time reversal lamb waves in a composite plate have been introduced firstly. Then the time reversal method has been adapted to detect the local defects in composite plate structures by using active sensing system mounted on a composite plate to excite and receive Lamb waves. This method can identify the location and size of the damage in a composite plate quickly without relying on past baseline date. The image that indicates the damage can be obtained by the ultrasonic tomography algorithm. Experimental results demonstrate the applicability and effectiveness of the proposed method.