Application of Pencil Lead Break (PLB) Point Source in the Detection of Interfacial Defects in Adhesive Bonds

Abstract The presence of kissing bonds (zero-thickness disbond) along the interface an adhesive bond is highly detrimental to its strength and longevity. detection these kind defects has previously been attempted using several techniques such as ultrasonic, infrared thermography, X-ray spectroscopy, etc. This study aims assess effectiveness pencil lead break (PLB) tests a source in detecting distributed bond. were introduced artificially polytetrafluoroethylene (PTFE) spray one interfaces fabricated with aluminium plates bonded epoxy adhesive. Three different interfacial defect area percentages, 0%, 25% 40% three layer thicknesses (i.e., 0.1 mm, 0.25 0.5 mm) considered. PLB conducted, recorded signals analysed variation AE features percentage thicknesses. Different source-sensor location configurations also 200 kHz-highpass component was found be sensitive defects. duration above chosen threshold distinguishing factor between defective specimens. Of sensor-source tried, on mm side seen