3軸応力下における接着層の降伏および破壊挙動

抄録

Stress states in adhesive layer of bonded joints are usually three-axial. However, yield and failure behavior under triaxial stress conditions have yet been clarified sufficiently. Two types of adhesive joints are available for investigating yield and fracture characteristics. One is scarf joint which has considerably uniform normal and shear stresses in the adhesive layer, where their combination ratio can be varied by changing scarf angle. Another is butt joint with thin wall tube in which considerably uniform pure shear stress state in the adhesive layer can be realized under torsional load condition. Furthermore, stress triaxiality which appeared in the adhesive layer of most of adhesive bonded joint can be reproduced by tensile tests of the scarf joint and torsional tests of the butt joint with thin wall tube. In this study, the effects of stress triaxiality on yield and failure stress were investigated by above mentioned tests using three kinds of adhesive with various ductility. The results showed that the yielding and failure criterion was changed by stress triaxiality and that the fracture mechanism of adhesive layer with homogeneous adhesive was different from the one with heterogeneous adhesive. Based on these experimental results, the method to predict the yielding and failure criteria were proposed by using the triaxiality parameter.