Nondestructive evaluation of adhesive joints by using nonlinear ultrasonic guided waves
Résumé
For a couple of decades, the use of bonded structures has been increasing in various industries. However, the non-destructive testing of such bonds is still challenging. While linear ultrasound is efficient to detect decohesion or voids in a structure, it is barely sensitive to bond strength. In this communication we present a method to generate high amplitude guided waves (GW) able to give birth to nonlinear effects after interaction with a defect at the bonded interface. In this purpose a new device has been developed, it acts as a two-dimensional virtual array and can be used to generate pure Lamb modes in a plate. Numerical simulation is employed to select the most appropriate guided mode-frequency combination. First the method for the generation of guided waves is presented, as well as measurements of its performances in terms of modal selectivity and amplitudes. Then the method is applied and evaluated on metallic bonds with bonding defects.