Experimental investigation on self-loosening of a bolted joint under cyclical temperature changes

Abstract

The most commonly used part in engineering fields is threaded fasteners. There are a lot of advantages of fasteners. One of them is that they can be easily disassembled and reused, but a bolted joint can loosen easily when a transversal load is applied. The clamp load of a bolted joint can also loosen slowly when subjected to repeated temperature changes. This paper presents an experimental investigation of the self-loosening of bolted joints under cyclical temperature variation. Experiments are carried out under several cyclical temperature changes with different bolt preloads. Rectangular threaded bolted joints with M12 × 1.75 bolts and nuts are tested in a specially designed testing apparatus. Material of bolt, nut, and plates is a stainless steel. The experimental results show that the high initial bolt preload may prevent the joint from self-loosening and the bolted joint has loosened significantly in the first cycle of temperature changes. From this investigation, the loosening of the bolted joint can be considered as a first stage self-loosening.

Self-Loosening of a 3D-Printed Bolt by Using Three Different Materials under Cyclical Temperature Changes

“…If a rotational load or dynamic axial load is applied to a bolted joint, loosening can take place in the joint [9,10]. Even if there are no external loads on bolted joints, they may loosen gradually under cyclical temperature changes [11,12]. This self-loosening phenomenon depends on the initial preload and amplitude of temperature variations.…”

“…Therefore, to choose a suitable material for bolts is very important in terms of self-loosening under cyclical temperature changes. As mentioned above, self-loosening may occur in bolted joints under cyclical temperature changes and this has been investigated by researchers for steel bolts [12,13], but self-loosening of a 3D-printed bolt under cyclical temperature changes has not been investigated before.…”