HYBRID NON-CONTACT GUIDED WAVE TOMOGRAPHY FOR IMAGING OF DEFECTS IN PLATE-LIKE STRUCTURE USING A PROBABILISTIC ALGORITHM

A hybrid non-contact testing with laser generated ultrasonic transmitter and an air-coupled transducer is very attractive technique in guided wave inspection. It can be used for online inspection and structural health monitoring (SHM) where contact method using embedded sparse sensors can not be applied such as the case of high temperature application. In this study, a tomography based on probabilistic algorithm was employed in conjunction with the hybrid non-contact method. This present approach can be successfully used for detecting, locating and imaging multi-defect in plates. The probabilistic algorithm is principally based on the use of signal difference coefficient of guided waves acquired for good and faulty conditions. The simplicity of this algorithm makes it suitable to be implemented to non-contact based online inspection scheme.