Development of anti-loosening nuts using shape memory alloys

A new kind of self-locking nuts which can prevent the fastener from loosening is developed using shape memory alloy. The transverse clamping force of SMA nuts on bolts caused by shape memory effect will always exist in the fastener, which can prevent it from vibrational loosening. A simplified method is proposed to estimate the loosening moment of the SMA nuts on the bolts. Comparison experiments on the conventional steel and SMA nuts were carried out on a vibration rig. Results show that the SMA nuts have good anti-loosening capability.