Tangential bond stiffness evaluation of adhesive lap joints by spectral interference of the low-frequency A0 lamb wave

Transmission spectra of the lowest-order antisymmetric (A0) Lamb wave for adhesively bonded single lap joints are experimentally investigated in a frequency range below 0.4 MHz. Based on theoretical results interference, tangential bond stiffness evaluation method is proposed joints. Aluminum alloy plates with epoxy adhesive different conditions were prepared as specimens. An air-coupled ultrasonic transducer was used to generate A0 mode specimens, and signals transmitted waves across measured pin-type piezoelectric transducer. Spectral analysis performed waveforms, transmission coefficient calculated each specimen function frequency. The experimental showed that has local maxima minima at multiple frequencies, called peak notch respectively. sets frequencies among estimated specimen. As result, stiffnesses obtained specimens same nominal thickness adherend pretreatment almost equal even if lengths different. Furthermore, pretreatments such sanding contamination surfaces affect due change interfacial stiffness.