Theoretical And Experimental Study On The Mechanical Properties Of Contact Interface By Elastic Waves

Contact interface is widely exist in nature, synthetic materials and engineering structures. When the materials or structures are impacted by the earthquake or the dynamic loads, separation and slip on the contact interface may occur, if the vibration or wave is strong enough, and the transmitted and reflected waves are distorted. Therefore, to study the effect of contact interface on the structural dynamic response is of important theoretical and realistic significance, which can provides the basis for vibration isolation and nondestructive testing of important structures.We carry out an exploration which includes theoretical analysis and experimental study on the mechanical properties and wave transmission characteristics of the contact interface under the applied loads. Many kinds of situations, such as different dielectric materials and different incidence angles, etc, are considered, the main research contents and conclusions are as follows:1. Based on the Fourier analysis method, we conduct a theoretical analysis on hamontic waves interraction with the contact interface, we get the analytical solution of the contact interface problems, give the area of interface separation and the distribution of adhesive, the relationship between displacements and the applied loads.2. Numerical calculation of the analytical solutions by MATLAB programming, shows that the transmission wave in higher order harmonics exists.due to the existence of the contact interface. The amplitude depends on the material on both sides of the contact interface, the incident wave and the incident angle. The case of same materials and different materials are considered. The transmitted and reflected waves of the fundamental frequency amplitudes, the second harmonic transmission wave amplitude, and the relative nonlinear coefficient chang with the applied loads are given.3.The loading device is designed independently. The influence of materials, incident angles, incident amplitude and the thickness of the speciment are tested and analyzed. The experimental results show that the existence of the contact interface results in higher harmonics in the transmited waves. The variation of fundamental harmonics, the second harmonics in transmitted waves and the relative nonliner coefficient with the applied loads are basically consistent with that of the theoretical results.4. The theoretical and experimental research on the variation of the second harmonics, the fundamental harmonics, and the relative nonlinear confficent with the aplided loads show that the forces on the contact interface can be estimated by the amplitude of the second harmonics inthe transmitted waves.which provide anew method for the determination of the mechanics characteristics of the contact interface.