Stress analysis at the interface of metal-to-metal adhesively bonded joints subjected to 4-point bending: finite element method.

Abstract

This paper presents a study of stress states in two-dimensional models of metal-to-metal adhesively bonded joints subjected to 4-point flexural loading using finite element (FE) method. The FE simulations were carried out on adhesive bonded joints of high support span to specimen thickness ratio undergoing extensive plastic deformations. Two different adhesive types with eight different adhesive layer thicknesses each varied between 50 μm to1500 μm were considered. The lower interfaces in the brittle adhesive were observed to be under a lower stress state because of the constraint exerted by a relatively stiff lower adherend. The ductile adhesive layers were under a lower state of stress as a result of the lower elastic modulus. It is concluded that the degree of plastic deformation in the adhesive is dictated by the adherend stiffness and the load transfer along the interface. The effect of load and support pins is noticeable at all adhesive thicknesses. High stress localisation exists in the vicinity of the load pins. The constraint exerted by the adherends dictates the deformation gradient through thickness of the adhesive layer. Adhesive joint behaviour as determined by the adhesive properties are investigated and also experimentally validated. Conclusions were drawn by correlating the adhesive and adherend stress states.