针对风力发电机螺栓由于预紧力松弛而导致的疲劳断裂问题,以风电塔筒环形法兰连接单段模型为研究对象,采用有限元的方法进行摩擦和常温蠕变对预紧力松弛的敏感性分析。结果表明：摩擦系数降低时螺纹最大应力降低了8.04%,平均应力增大了16.4%,且材料蠕变特性较低和屈服应力较高时预紧力仅分别减小了15.74%和6.37%。因此,当螺纹接触处和外部接触表面的摩擦较低,且螺栓材料具有较低蠕变特性和较高屈服强度时,螺栓抗蠕变性能较好且不易发生预紧力松弛现象。此时螺栓连接状态和预紧力分布较好,螺纹最大应力较小,且法兰间的接触压强和夹紧力较高,有效减小了预紧力松弛。研究结果为解决风电螺栓预紧力松弛问题提供了理论依据。
Abstract
Aiming at the problem of the fatigue fracture of wind turbine bolts due to preload relaxation, a single-section model of wind turbine tower ring flange connection is used to analyze the sensitivity of preload relaxation caused by friction and room temperature creep using the finite element method. The results show that the maximum thread stress decreases by 8.04% and the average stress increases by 16.4% when the friction coefficient is reduced, and the preload only decreases by 15.74% and 6.37% respectively when the material creep characteristics are low and the yield stress is high. Therefore, when the friction between the thread contact and the external contact surface is low, and the bolt material has low creep characteristics and high yield strength, the bolt has better creep resistance and is less prone to preload relaxation. At this time, the bolt connection state and preload distribution are better, the maximum stress of the thread is smaller, and the contact pressure and clamping force between the flanges are higher, which effectively reduces the preload relaxation. The research results provide a theoretical basis for solving the problem of preload relaxation of wind turbine bolts.
关键词
风力发电机 /
螺栓 /
摩擦 /
蠕变 /
预紧力松弛
Key words
wind turbines /
bolts /
friction /
creep /
preload relaxation
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