本文關(guān)鍵詞：基于有限元和斷裂力學(xué)的起重機裂紋故障研究　出處：《武漢科技大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 裂紋 焊址 啃軌力 子模型 ANSYS3D斷裂模型

【摘要】：起重機是工程實際中的重要設(shè)備，隨著國民經(jīng)濟的快速發(fā)展，它在工程實際中發(fā)揮的作用越來越來巨大。與此同時，由于高頻率和高負荷的工作，使得起重機故障不斷，其中最常見也最危險的是金屬結(jié)構(gòu)疲勞裂紋故障，裂紋故障易引發(fā)結(jié)構(gòu)破斷從而引發(fā)重大事故，因此對起重機疲勞裂紋故障的研究成為現(xiàn)代工程中一個重要課題。本文以某公司第三鋼軋廠高跨4#125t×22m鑄造起重機主梁裂紋為研究對象，以有限元軟件ANSYS為研究工具，分析了該起重機疲勞裂紋產(chǎn)生的原因，并提出裂紋止裂修復(fù)措施，最后驗證了修復(fù)的可行性，為起重機同類型裂紋的研究和修復(fù)提供了參考。本文所做的主要工作如下： （1）對該起重機主腹板裂紋故障產(chǎn)生的原因進行了分析和研究，利用有限元軟件ANSYS分工況對起重機主梁進行了靜強度分析，通過分析對比，，發(fā)現(xiàn)啃軌力的作用致使主腹板與隔板的焊址處產(chǎn)生較大脈動應(yīng)力及焊接殘余應(yīng)力過大是主腹板上裂紋產(chǎn)生的兩個主要原因。 （2）基于線彈性斷裂力學(xué)對該起重機主梁的疲勞裂紋進行了壽命估算，計算出了含初始缺陷的主梁裂紋擴展設(shè)計壽命和該起重機理論使用壽命，并通過計算所得的主梁裂紋擴展剩余壽命得出這些主梁裂紋亟待修補的結(jié)論。 （3）依據(jù)斷裂力學(xué)裂紋止裂修復(fù)理論，提出了主梁裂紋修復(fù)措施，并對修復(fù)后的主梁再一次進行有限元分析。分析過程采用了ANSYS子模型技術(shù)，對裂紋故障部位單獨建模分析，使計算效率和精度明顯提高。通過修補前后的應(yīng)力對比分析，得知裂紋位置的應(yīng)力水平經(jīng)修補后有了明顯下降，且應(yīng)力水平降至安全范圍之內(nèi)。這個結(jié)論驗證了筆者采取的修復(fù)措施的可行性。 （4）結(jié)合ANSYS3D斷裂模型與子模型技術(shù)對裂紋區(qū)域進行了模擬，計算出了裂紋尖端的應(yīng)力水平及應(yīng)力強度因子幅度Δ K。利用ΔK對修補后的裂紋進行擴展判定和壽命評估，得知裂紋經(jīng)修復(fù)后不會再擴展，從而進一步驗證了修補方案的可行性。
[Abstract]:Crane is an important equipment in engineering practice. With the rapid development of national economy, it plays a more and more important role in engineering practice. At the same time, because of high frequency and high load work. The most common and dangerous fault of crane is the fatigue crack fault of metal structure, which can easily lead to structural breakage and lead to serious accident. Therefore, the research on the fatigue crack fault of crane has become an important subject in modern engineering. In this paper, the main beam crack of #4125t 脳 22m foundry crane in the third steel mill of a company is taken as the research object. With the finite element software ANSYS as the research tool, the causes of the fatigue crack in the crane are analyzed, and the crack arrest and repair measures are put forward. Finally, the feasibility of the repair is verified. This paper provides a reference for the study and repair of the same type cracks in cranes. The main work of this paper is as follows: 1) the causes of the main web crack of the crane are analyzed and studied, and the static strength of the crane main girder is analyzed by using the finite element software ANSYS. It is found that the two main causes of cracks on the main web are the large pulsating stress at the welding site of the main web and the excessive welding residual stress due to the action of the gnawing force. Based on the linear elastic fracture mechanics, the fatigue crack life of the main girder of the crane is estimated, and the design life of the crack propagation of the main girder with initial defects and the theoretical service life of the crane are calculated. By calculating the residual life of crack propagation in the main beam, the conclusion that these cracks need to be repaired is obtained. 3) according to the theory of crack stopping and repairing in fracture mechanics, the measures of repairing main beam crack are put forward, and the finite element analysis of the main beam after repairing is carried out again. The ANSYS sub-model technique is used in the analysis process. The calculation efficiency and precision are improved obviously by modeling and analyzing the crack fault location separately. Through the comparative analysis of stress before and after repair, it is known that the stress level of the crack position has obviously decreased after repairing. And the stress level is within the safe range. This conclusion verifies the feasibility of the restoration measures taken by the author. (4) ANSYS3D fracture model and sub-model technique are used to simulate the crack region. The stress level and the amplitude of stress intensity factor 螖 K at the crack tip are calculated. The crack propagation and life evaluation are made by using 螖 K, and it is found that the crack will not propagate after repair. Thus, the feasibility of the repair scheme is further verified.
【學(xué)位授予單位】：武漢科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH21

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