为明确螺栓抵抗松动的能力，指导螺栓在使用中的选型，以抑制螺纹面局部滑移为防松条件，通过对同一螺纹面周向不同位置的受力进行分析，推导得到了横向载荷作用下螺栓临界松动载荷的数值计算公式。采用横向振动试验装置和该数值计算方法，分别测试和计算了尺寸规格为M5的螺栓在夹紧力为2 000 N、2 500 N时的临界松动载荷。结果表明，夹紧力为2 000 N时临界松动载荷的试验与计算结果分别为302.5 N、280.3 N，2 500 N时试验与计算结果分别为372.5 N和350.4 N。两种夹紧力条件下试验与计算结果相对误差分别为7.3%（2 000 N）和5.9%（2 500 N），这验证了该数值计算方法的准确性及可靠性。基于该公式，分析了螺栓结构参数对临界松动载荷的影响。结果表明，增大夹紧力、螺纹面摩擦因数、螺栓直径以及牙型角，降低螺栓夹紧长度、螺纹升角，可以增大临界松动载荷，提高螺栓抵抗松动的能力。
In order to evaluate the anti-loosening ability of bolt and guide the selection of the bolt in use, a numerical formula of critical load for bolt loosening is obtained through the force analysis in different circumferential positions of thread. Inhibiting localized thread slip is the condition of avoiding loosening in the formula derivation. The critical loads of the M5 bolts under 2 000 N and 2 500 N preloads are tested by the transverse vibration device and calculated by the numerical formula, respectively. The results show that the critical loads obtained by test and calculation are 302.5 N and 280.3 N for the bolt with 2 000 N preload, 372.5 N and 350.4 N for the bolt with 2 500 N preload. The relative errors between the test and calculation results are 7.3% (2 000 N) and 5.9% (2 500 N) respectively, confirming the accuracy and reliability of the numerical formula. Then, the effect of the structure parameters of bolt on the critical load for bolt loosening is analyzed based on the numerical formula. The results show that increasing the clamping load, the thread friction coefficient, the bolt diameter, the thread angle, and decreasing the clamping length, the lead angle, can contribute to increasing this critical load, and improve the anti-loosening ability of bolt.
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