THE PHASE SHIFT OF SH₀GUIDED WAVE PROPAGATING IN BONDING STRUCTURE

It is a difficult and challenging subject for non-destructive testing and evaluation of adhesive structure by ultrasonic guided waves.For this issue, the phase shift of SH ₀guided wave transmitting in perfect connected trilaminar plate-like adhesive structure was researched.Firstly, the phase-difference analytical model between the incident and transmission/reflection SH ₀guided wave, which based on the control equation of wave propagation, was established.Then, the phase-difference curves of reflection/transmission SH ₀guided wave in aluminum/epoxy resin/aluminum adhesive structure were calculated by numerical simulation.Finally, the effects of changes of incident angle and frequency-thickness product on the phase-difference of reflection/transmission SH ₀guided wave were analyzed.The results show that the changes of phase-difference of reflection/transmission SH ₀guided wave transmitting in adhesive structure mainly depend on the parameter as incident angle or frequency of acoustic wave, for the concrete bonding structure.The reflection and incident SH ₀guided waves are in the same phase when the ultrasound is incident under a particular frequency-thickness product.Despite the angle of incidence, the phase-difference curve of reflection SH ₀guided wave shows periodic res-onance with the increasement of frequency-thickness product.For the transmission SH ₀guided wave, the change of the phase-difference curve has no law to follow when the ultrasound is normal incident.But the phase-difference curve changes from irregularity to regularity as the angle of incidence increase.The results obtained could provide the theory support for studying the propagation characteristics of SH ₀guided wave in plate-like bonding structure and information retrieving of echoed SH ₀guided wave and positioning during the experiment.