Two different studies by North Carolina State University (NSCU) department of mechanical & aerospace engineering prove the science behind ReLok™
It is commonly observed that nuts and bolts when used on vibrating structure are
subjected to a phenomenon called 'vibrational loosening'. The main cause for this is the side sliding of
nut or bolt head relative to the joint.
This movement causes relative motion between the threads of the nut and bolt. The self-loosening causes a
reduction in the clamp force which results in joint slip. As a consequence of this, the bolt is subjected to
bending loads and finally fails by fatigue.
The main reasons of relative motion are: bending of parts that causes induction of forces at the friction
surface, differential thermal effects caused by temperature or material difference, applied forces on the
joint can lead to shifting of the joint surfaces leading to relative motion and hence loosening.
To address this problem of self-loosening, a new mechanism is proposed where a bolt with annulus is
surrounded by a collar circumferentially. When the bolt is pushed into the collar, the annulus will
deflect inward while the collar would deflect outward. This way both the annulus and the collar will
store energy in them. Now, when there is motion of the two surfaces being held together by the bolt and
collar which might lead to loosening, the stored strain energy would help to keep the joint tight.