平板の重ね接着部におけるラム波反射・透過特性の数値解析

抄録

The reflection and transmission of Lamb waves at an adhesively bonded lap joint of plates are numerically analyzed by hybrid finite element method (HFEM). The adhesive joint is modeled as a linear spring-type interface characterized by normal and tangential stiffnesses. The numerical analysis is carried out for a low frequency range in which only the lowest-order symmetric (S0) and antisymmetric (A0) modes can propagate in adherends. For the A0 mode incidence, not only the reflection and transmission of the A0 mode occurs at the joint but also the S0 mode is generated as reflected and transmitted waves due to mode conversion. The numerical results show that the reflection and transmission coefficients of both modes exhibit local maxima/minima at different frequencies. This behavior results from multiple reflection between the edges of the overlap region. The peak frequencies of the A0 mode reflection/transmission coefficients depend only on the tangential stiffness of the interface, not on the normal stiffness. The theoretical prediction shows that in the overlap region, i.e., a bonded double-layer plate, two types of guided wave modes, symmetric and antisymmetric modes, can propagate. Since the dispersion properties of the symmetric and antisymmetric modes depend only on the normal and tangential stiffnesses, respectively, the antisymmetric modes are found to play an important role in the multiple reflection leading to the peak behavior of the A0 mode reflection and transmission coefficients.