一般的螺纹紧固件在承受振动冲击载荷作用时,常常会因为自松而失效。产生自松的直接原因是,由于动载荷的作用,使螺纹与支承面产生微小的相对位移,摩擦系数由较高的静态值变为很低的动态值,总力矩趋近于零,作用在螺纹上的轴向力在圆周上形成了一个导致螺栓或螺母松脱的力。经千万次振动循环后,使螺纹丧失防松摩擦阻力,乃至完全松脱。 General threaded fasteners often fail due to looseness when subjected to vibration impact loads. The direct cause of looseness is due to the fact that due to the action of the dynamic load, a slight relative displacement between the thread and the bearing surface occurs. The friction coefficient changes from a higher static value to a very low dynamic value, and the total torque approaches zero. The axial force on the thread creates a force on the circumference that causes the bolt or nut to loosen. After tens of millions of vibration cycles, the thread loses its anti-friction resistance, or even completely looses.