Inspection of Dissimilar Material Joints Using Ultrasonic Phased Arrays

Ultrasonic Inspection is widely used non-destructive testing technique. However, there are limited studies in the field of inspection of metal-composite adhesive joints. Since properties of dissimilar materials are different, reflection from the bonding between metal and composite occurs even without defects in the joint, what complicates the detection of defects in the joint. This work presents numerical and experimental study of ultrasonic inspection of metal-composite adhesive joints. The numerical investigations were carried out using CIVA software. In this work phased array transducers of 3.5 MHz and 5 MHz frequency were studied and compared. It was determined, that there is a bigger possibility to detect delaminations using 3.5 MHz transducer due to stronger signal, but the complexity of defect detection is caused by dissimilar joint itself - ultrasonic signal at the interface composite-metal is reflected even without defects in it. In order to improve the probability of defect detection in the interface the analysis of multiple reflections from the bonding zone was proposed.