The high-strength hexagonal bolts can be loosened only one hundred times in the transverse vibration loosening experiment, and the fatigue strength test needs to be repeatedly vibrated one million times. In other words, the high-strength hexagonal bolts loosen when they use one ten-thousandth of their fatigue strength. We only use one ten-thousandth of its capacity. Therefore, the loosening of high-strength hexagonal bolts is not due to the bolts. Fatigue strength.
After the high-strength hexagonal bolts are loosened, huge kinetic energy mv2 is generated. This huge kinetic energy directly acts on the bolts and equipment, causing the bolts to be damaged. After the bolts are damaged, the equipment cannot work under normal conditions, which further leads to equipment damage. For fasteners that are subjected to axial force, the threads are broken and the bolts are broken. For fasteners that are subjected to radial force, the bolts are cut, and the bolt holes are punched into an ellipse.
In the case of vibration and impact, high-strength hexagonal bolts will tend to loosen. However, because the loosening direction of the tightening nut is the tightening direction of the lock nut, the tightening of the lock nut just prevents the loosening of the tightening nut. The tightening nut cannot be loosened due to retraction.
