發(fā)布時間：2018-07-30 07:35

【摘要】：高強度螺栓廣泛應(yīng)用在各種重要設(shè)備中,其失效會造成嚴(yán)重的后果。螺栓最主要的失效形式是疲勞斷裂,所以研究高強度螺栓的疲勞問題,建立正確的高強度螺栓的疲勞預(yù)測方法,準(zhǔn)確分析螺栓結(jié)構(gòu)的應(yīng)力應(yīng)變分布,并提出較高疲勞強度的螺栓結(jié)構(gòu),具有重要意義。本文是利用有限元軟件模擬螺栓結(jié)構(gòu)來進(jìn)行研究,主要工作包括三個方面。 考慮高強度螺栓的螺牙根部常出現(xiàn)局部屈服的特點,選擇基于彈塑性有限元分析的局部應(yīng)力法來預(yù)測結(jié)構(gòu)的疲勞壽命。設(shè)計了測定螺栓壽命的疲勞試驗,通過試驗結(jié)果和理論計算結(jié)果對比,驗證了這種方法的可行性和準(zhǔn)確性。 利用通用有限元分析軟件ABAQUS對螺栓結(jié)構(gòu)進(jìn)行有限元分析,考慮材料的彈塑性和接觸非線性,分析螺栓結(jié)構(gòu)的各部分的應(yīng)力應(yīng)變分布,并總結(jié)出各螺牙承載不均勻性的規(guī)律。研究螺栓和螺母的螺紋配合圈數(shù),接觸面的摩擦系數(shù),螺紋根部過度圓角半徑這幾個因素對螺栓受力狀態(tài)的影響。此外,對比了在有限元建模過程中,采用回轉(zhuǎn)簡化模型和采用螺旋模型的計算誤差。 在上述基礎(chǔ)上,提出若干種螺栓結(jié)構(gòu)疲勞強度優(yōu)化的思路和方法,并利用有限元法進(jìn)行建模驗證。具體措施包括以下幾個： (1)增大螺紋根部的圓角深度,增大根部的過渡圓角半徑。 (2)按一定規(guī)律改變螺母的螺距,有規(guī)律的切削螺母的受力螺紋面。 (3)改變螺栓齒高,一定斜度斜切其螺牙,使接觸的前幾號螺牙齒高減小。 (4)改變螺母牙側(cè)角,在螺母的牙根處取一個段牙側(cè)角為600的楔形斜面。 (5)減小螺栓結(jié)構(gòu)的剛度,達(dá)到減小螺栓承受的動載荷的幅度的目的。
[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.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH131.3

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