Axisymmetric stress analysis and strength of bonded shrink-fitted joints subjected to push-off forces and torsional loads

Abstract

Shrink fittings have been used commonly for joining cylindrical components such as shafts and gears in mechanical structures. Recently a shrink fitted joint with an anaerobic adhesive (bonded shrink fitted joint) has been used in order to improve the joint strength and to reduce the assembly weight. In a reliable design of bonded shrink fitted joints, it is necessary to know the contact stress distributions at the interfaces. In this paper, the interface stress distributions of bonded shrink fitted joints under a push-off force and a torsional load are analyzed by using axisymmetric theory of elasticity as contact problems. A test was conducted to determine the relationship between the normal stress and the shear stress (this test is called an analogous test). Using the interface stress distributions and the test results, a method for estimating the joint strength is proposed. In the numerical calculations, the effect of the outer diameters and Young’s moduli of the rings and the engagement length on the contact stress distributions at the interfaces are examined. The joint strengths of bonded shrink fitted joints under a push-off force as well as a torsional load were measured. In the experiments, the effect of the shrink fitted interference and the outer diameter of the ring on the joint strength were examined. The numerical results are in a fairly good agreement with the experimental results. It is found that the strength of a bonded shrink fitted joint is greater than that of a shrink fitted joint subjected to both the push-off force and the torsional load.