Study on Macroscale Evaluation of Interfacial Stiffness of Multi-Material Structures

(Comparison with Microscale FEM by Using Surface Profile of Interfaces)

Abstract

Multi-material structures are constructed by screw bolts in addition to welding and adhesion. However, the interfacial stiffness of the bolted joints is often lower than that of the welding part etc. and varied by the clamping force of the bolt and the nut, because the micro asperities formed on the interfaces just contact each other. The contact analysis by using the surface texture of the interfaces in microscale is one of the accurate estimations. However, the estimation method of the interfacial stiffness in macroscale is also necessary for the in-situ evaluation. This study has proposed an evaluation method of the interfacial stiffness from the natural frequency of the structure in macroscale. The hammering test was performed by using the specimen which consisted of the aluminum alloy plate and the steel plate joined by the bolts and the nuts. Moreover, the finite element method (FEM) in microscale simulated the contact of the asperities formed on the interfaces. The interfacial stiffness estimated by the proposed method agreed with that by the microscale FEM.