Self loosening behavior of bolted joints under transverse cyclic loading.

Abstract

Although plastic materials are widely used as insulators in electric equipment, the mismatch of the thermal expansion cefficients between the plastic and the metallic materials may cause problems. For instance, in bolted joint structures the mismatch of the thermal expansion coefficients causes transverse cyclic relative slippage and loosening of bolts. In the work described in this paper the loosening behavior of these bolted joints under transverse loading was analyzed taking into account the relative slippage on the interface between the bolt head and the jointed body. The amount of slippage was calculated using this mismatch of the thermal expansion between both the jointed bodies and the bending elastic deformation of the bolts. The analytical results were confirmed by experimental results. Using these results we identify highly durable bolted fastening structures.