An ultrasonic horn originally designed for welding has generally been used for thermosonic testing. However, it is difficult to obtain reproducible and controllable excitation with the existing horn system because of nonlinearity in the coupling; surface damage can also be produced by chattering caused by loss of contact between the tip of the horn and the structure. Therefore, this research was conducted to develop a simple excitation system that should excite sufficient strain for the detection of the defects of interest at all relevant positions in the structure, and should also be easy to attach to and remove from the structure. It must also avoid surface damage. Test results suggest that a simple, small wax coupled PZT exciter may provide a convenient, reliable thermosonic test system in applications such as composite structures and electronic materials where relatively low strain levels are required for damage detection.
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