Axisymmetric Analysis of Mechanical Properties of Bonded Shrink Fitted Joints Under Torsional Loads

Abstract

Shrink fitting combining with anaerobic adhesives (bonded shrink fitted joints) has been widely used for joining cylindrical components in a lot of mechanical structures. This paper deals with mechanical properties (stress analysis and strength estimation) of the bonded shrink fitted joint in which a ring is fitted at the middle part of a shaft subjected to torsion. The stress distributions in the adhesive layer of bonded shrink fitted joint are analyzed using an axisymmetric theory of elasticity when an external torsion is applied to the upper end of the shaft. The effects of the stiffness, the outside diameter and the height of the ring on the interface stress distributions are clarified in the numerical calculations. The maximum shear stress, which shows singular stress property, initiates near the inside upper edge of the adhesive layer interface, where the rupture occurs in the joint under external torsional loads. In addition, the estimation method of joint strength is applied using the interface stress distributions and the modified singularity stresses expressions obtained from the analogous tests. It is found that the joint strength increases as the stiffness, the outside diameter and the height of the ring increase. Furthermore, experiments to measure the joint strength were carried out. Three-dimensional finite element (FEM) method is also adopted to verify the theoretical results. In addition, the strength of the bonded shrink fitted joint is compared with that of shrink fitted joint based on the experimental results, which is found that the strength of the bonded shrink fitted joints is greater than that of shrink fitted joints. The numerical results are in a fair good agreement with the experimental results and FEM results.