Non-linear acoustics and adhesion measurements of interfaces: techniques for the inspection of bonded structures

At the present state-of-the-art, nondestructive testing techniques can only distinguish between a complete delamination or complete bonding. It is difficult to judge an intermediate state of bonding. With the technique presented, this gap can be closed. However, much more theoretical work has to be undertaken in order to obtain an absolute calibration of the technique and to strengthen its application. From a practical point of view, probes have to be developed which are linear at least up to the strains and existing electronic equipment has to be adapted