平板の突合せ接触部におけるラム波の透過特性と接触界面剛性

抄録

Transmission characteristics of the lowest-order symmetric (S0) and antisymmetric (A0) Lamb modes at contacting edges of plates are experimentally examined. The edges of two aluminum alloy plates were mated together and a compressive load was applied from both plate ends to constitute a butt-type contacting interface. Wedge transducers were used to emit and detect a single Lamb mode dominantly. For the excitation of the S0 mode, the transmission coefficient of the S0 mode increases with increasing contact pressure and slightly decreases with increasing frequency. For the excitation of the A0 mode, on the other hand, the transmission coefficient of the A0 mode shows complicated behavior with contact pressure and frequency. When the contacting edges of the plates are modeled as a linear spring-type interface which is characterized by normal and tangential stiffnesses, the transmission coefficients of the S0 and A0 modes below the cut-off frequencies are approximated by the results of thin-plate theories. Comparison of the measured transmission coefficients to the theoretical results enables the estimation of the interfacial stiffnesses of contacting edge faces. The estimated normal and tangential stiffnesses show increasing behavior with increasing contact pressure. The dependence of the measured transmission coefficients on frequency and contact pressure is well reproduced by the theoretical results based on the estimated interfacial stiffnesses.