Adhesive Bond Imaging by Noncontact Measurements With Single-Sided Access

Adhesive bonding, an effective joining technique for platelike structures in aircraft and automobiles, requires postbond inspection preferably with noncontact and single-sided access. The present study discusses the application of an imaging technique with a scanning laser source (SLS) to evaluate adhesive bonds in a platelike structure. When a laser Doppler vibrometer (LDV) is used as a receiver, the SLS technique realizes noncontact measurements with single-sided access. The imaging experiments that used narrowband burst waves and broadband chirp waves indicated that the imaging technique is appropriately applied to adhesive bonds and that the use of broadband chirp waves provides clearer images and reduces spurious images due to resonance. Furthermore, images of adhesive bonds were clearly obtained for a complex plate structure that consisted of a top-hat section and a flat plate, and this demonstrates that the imaging technique can be widely applied to evaluate various adhesive bonds.