Evaluation for Clamping Force Reduction of Bolted Joints under Relaxation of Jointed Body.

Abstract

Copper alloys are widely used as conductors in electrical equipment. In these cases the mismatch of thermal expansion coefficients between copper alloy and other materials may cause frequent mechanical problems. For instance, in bolted joint structures the mismatch of thermal expansion coefficients causes transverse cyclic relative slippage and loosening of bolts. In this paper the relaxation behavior of these bolted joints was analyzed by considering the relaxation characteristics of the jointed body, and the tlnermal expansion mismatch between steel bolts and jointed body materials. The analytical results were confirmed by the experimental results. Using these results we can propose some fastening criteria for maintaining long-term reliability.