SH0导波在粘接结构中传播时的相位变化1）

对粘接结构进行超声导波无损检测与评估是一个有挑战性的前沿性课题.针对此问题，研究了SH₀导波在界面为理想连接的三层板状粘接结构中传播时的相位变化情况.首先基于波传播的控制方程，建立了粘接结构中反射和透射SH₀导波相对于入射SH₀导波的相位差解析模型.然后利用数值模拟计算了铝/环氧树脂/铝粘接结构中反射和透射SH₀导波的相位差曲线.最后分析了入射角度和频厚积的变化对反射和透射SH₀导波相位差的影响.结果表明，对于具体的粘接结构，反射和透射SH₀导波在其中传播时的相位差变化主要依赖于入射角度、频率等参数.在特定的频厚积下，当声波水平入射时，反射和入射SH₀导波同相位.无论入射角度为多大，随着频厚积的增大，反射SH₀导波的相位差曲线均会产生周期性谐振.对于透射SH₀导波，当声波垂直入射时，其相位差曲线的改变无规律可循；但是随着入射角度逐渐增大，透射SH₀导波的相位差曲线逐渐变规则.所得结果可为实验时研究板状粘接结构中SH₀导波的传播特性以及提取SH₀导波回波中的有用信息和定位提供一定的理论指导.

THE PHASE SHIFT OF SH0 GUIDED WAVE PROPAGATING IN BONDING STRUCTURE 1)

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 SH₀ guided wave transmitting in perfect connected trilaminar plate-like adhesive structure was researched.Firstly, the phase-difference analytical model between the incident and transmission/reflection SH₀ guided wave, which based on the control equation of wave propagation, was established.Then, the phase-difference curves of reflection/transmission SH₀ guided 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 SH₀ guided wave were analyzed.The results show that the changes of phase-difference of reflection/transmission SH₀ guided 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 SH₀ guided 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 SH₀ guided wave shows periodic res-onance with the increasement of frequency-thickness product.For the transmission SH₀ guided 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 SH₀ guided wave in plate-like bonding structure and information retrieving of echoed SH₀ guided wave and positioning during the experiment.