高强度螺栓的应力分析及结构疲劳强度优化

发布时间：2018-07-30 07:35

【摘要】：高强度螺栓广泛应用在各种重要设备中,其失效会造成严重的后果。螺栓最主要的失效形式是疲劳断裂,所以研究高强度螺栓的疲劳问题,建立正确的高强度螺栓的疲劳预测方法,准确分析螺栓结构的应力应变分布,并提出较高疲劳强度的螺栓结构,具有重要意义。本文是利用有限元软件模拟螺栓结构来进行研究,主要工作包括三个方面。考虑高强度螺栓的螺牙根部常出现局部屈服的特点,选择基于弹塑性有限元分析的局部应力法来预测结构的疲劳寿命。设计了测定螺栓寿命的疲劳试验,通过试验结果和理论计算结果对比,验证了这种方法的可行性和准确性。利用通用有限元分析软件ABAQUS对螺栓结构进行有限元分析,考虑材料的弹塑性和接触非线性,分析螺栓结构的各部分的应力应变分布,并总结出各螺牙承载不均匀性的规律。研究螺栓和螺母的螺纹配合圈数,接触面的摩擦系数,螺纹根部过度圆角半径这几个因素对螺栓受力状态的影响。此外,对比了在有限元建模过程中,采用回转简化模型和采用螺旋模型的计算误差。在上述基础上,提出若干种螺栓结构疲劳强度优化的思路和方法,并利用有限元法进行建模验证。具体措施包括以下几个： (1)增大螺纹根部的圆角深度,增大根部的过渡圆角半径。 (2)按一定规律改变螺母的螺距,有规律的切削螺母的受力螺纹面。 (3)改变螺栓齿高,一定斜度斜切其螺牙,使接触的前几号螺牙齿高减小。 (4)改变螺母牙侧角,在螺母的牙根处取一个段牙侧角为600的楔形斜面。 (5)减小螺栓结构的刚度,达到减小螺栓承受的动载荷的幅度的目的。
[Abstract]:High-strength bolts are widely used in all kinds of important equipments, and their failure will cause serious consequences. The main failure form of bolt is fatigue fracture, so the fatigue problem of high strength bolt is studied, the correct fatigue prediction method of high strength bolt is established, and the distribution of stress and strain of bolt structure is analyzed accurately. The bolt structure with high fatigue strength is of great significance. In this paper, the finite element software is used to simulate the bolt structure, the main work includes three aspects. The local stress method based on elastic-plastic finite element analysis is chosen to predict the fatigue life of the structure. A fatigue test was designed to measure the life of bolts. The feasibility and accuracy of this method were verified by comparing the experimental results with the theoretical results. The finite element analysis of bolt structure is carried out by using the universal finite element analysis software ABAQUS. Considering the elastic-plastic and contact nonlinearity of the material, the stress-strain distribution of each part of the bolt structure is analyzed, and the law of uneven bearing capacity of each screw tooth is summarized. The influence of the number of thread matching rings, the friction coefficient of the contact surface and the radius of the excessive fillet of the thread root on the stress state of the bolt is studied. In addition, the calculation errors of simplified rotary model and spiral model in finite element modeling are compared. On the basis of the above, some ideas and methods of fatigue strength optimization of bolt structures are put forward, and the finite element method is used to model and verify them. Specific measures include the following: (1) increasing the fillet depth of the thread root and increasing the radius of the transition angle of the root; (2) changing the pitch of the nut according to certain laws, (3) changing the height of the bolt teeth, a certain angle oblique to cut the screw teeth, so as to reduce the height of the first few screw teeth in contact. (4) change the side angle of the nut teeth, (4) change the side angle of the nut tooth, (4) change the side angle of the nut tooth, At the root of the nut, a wedge-shaped slope with a side angle of 600 segments is taken. (5) the stiffness of the bolt structure is reduced, and the amplitude of the dynamic load of the bolt is reduced.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH131.3

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