System and method for multi-frequency sonic excitation in infrared imaging

摘要

A defect detection system (10) for thermally imaging a structure (12) that has been energized by a sound energy. The system (10) includes a transducer (14) that couples a sound signal into the structure (12), where the sound signal causes defects in the structure (12) to heat up. In one embodiment, the sound signal has one or more frequencies that are at or near an eigen-mode of the structure (12). In another embodiment, a non-linear coupling material (16) is positioned between the transducer (14) and the structure (12) to couple the sound energy from the transducer (14) to the structure (12). A predetermined force (26) is applied to the transducer (14) and a pulse duration and a pulse frequency of the sound signal are selected so t hat the sound energy induces acoustic chaos in the structure (12), thus generating increased thermal energy. A thermal imaging camera (22) images the structure (12) when it is heated by the sound signal.