【摘要】：橋式起重機(jī)作為現(xiàn)代工業(yè)生產(chǎn)與起重運(yùn)輸業(yè)中必不可少的特種設(shè)備之一,目前已廣泛應(yīng)用于在鐵路交通、鋼鐵化工、港口碼頭以及物流周轉(zhuǎn)等部門和場所。然而,橋式起重機(jī)卻是大型機(jī)械設(shè)備中隱藏危險(xiǎn)因素最多、發(fā)生傷亡事故幾率最大的特種設(shè)備,國內(nèi)外每年不斷頻發(fā)的起重設(shè)備事故,造成了極其嚴(yán)重的人身傷害及財(cái)產(chǎn)損失。根據(jù)大量統(tǒng)計(jì)資料顯示,這些事故中,最常見、最嚴(yán)重的是以疲勞裂紋為特征的橋式起重機(jī)焊接箱形主梁結(jié)構(gòu)的疲勞破壞。橋式起重機(jī)的箱形主梁結(jié)構(gòu)是其主要的承載構(gòu)件,橋式起重機(jī)的工作特點(diǎn)決定了此類結(jié)構(gòu)的主要破壞形式為隨機(jī)載荷作用下主梁的疲勞斷裂,而主梁的斷裂就意味著整個(gè)橋式起重機(jī)壽命的終結(jié)。因此,進(jìn)行在役橋式起重機(jī)箱形主梁結(jié)構(gòu)的疲勞裂紋擴(kuò)展規(guī)律的研究和箱形主梁剩余疲勞壽命的預(yù)測,可以預(yù)防其疲勞斷裂破壞事故的發(fā)生,并對(duì)于橋式起重機(jī)的設(shè)計(jì)、制造、使用及維修具有重要的指導(dǎo)意義。 本課題運(yùn)用現(xiàn)代疲勞累積損傷理論,分析橋式起重機(jī)箱形主梁疲勞破壞的特征及其影響因素;采用ANSYS有限元分析軟件對(duì)橋式起重機(jī)箱形主梁結(jié)構(gòu)進(jìn)行靜力學(xué)分析,確定其危險(xiǎn)部位并對(duì)其進(jìn)行疲勞分析與剩余壽命估算。另外,本課題還結(jié)合斷裂力學(xué)理論對(duì)已產(chǎn)生疲勞裂紋的箱形主梁結(jié)構(gòu)進(jìn)行剩余疲勞壽命預(yù)測,這對(duì)于提高橋式起重機(jī)工作的可靠性,延長其使用壽命,進(jìn)而提高起重機(jī)在工程實(shí)際中的生產(chǎn)效率具有重要意義。 首先,本文建立了該橋式起重機(jī)箱形主梁結(jié)構(gòu)的有限元模型,選擇起重機(jī)的五種典型工況,在近似于實(shí)際工作條件的疲勞載荷分布狀態(tài)下對(duì)無缺陷的箱形主梁結(jié)構(gòu)進(jìn)行有限元模擬分析,得到了箱形主梁結(jié)構(gòu)在每種工況下的應(yīng)力、位移變形以及安全系數(shù)分布圖,確定了箱形主梁結(jié)構(gòu)應(yīng)力值與位移變形量的最大位置和安全系數(shù)最低的部位。 其次,采用ANSYS有限元分析軟件中的壽命分析模塊對(duì)含有初始裂紋的橋式起重機(jī)主梁結(jié)構(gòu)的設(shè)計(jì)壽命進(jìn)行估算,并通過模擬結(jié)果分析,得出含有初始裂紋的箱形主梁結(jié)構(gòu)在近似實(shí)際工況下的安全系數(shù)分布圖以及疲勞壽命云圖,直觀地反映出了箱形主梁結(jié)構(gòu)各部位的疲勞壽命分布狀態(tài)。 最后,本課題采用線彈性斷裂力學(xué)的方法,估算了該橋式起重機(jī)端梁危險(xiǎn)部位的疲勞擴(kuò)展壽命和箱形主梁結(jié)構(gòu)的剩余壽命,并繪制出了箱形主梁結(jié)構(gòu)端部腹板處疲勞裂紋長度與該起重機(jī)循環(huán)次數(shù)的關(guān)系曲線圖。再把有限元模擬的分析結(jié)果與實(shí)測結(jié)果相比對(duì),發(fā)現(xiàn)兩者是基本吻合的,證明了該種箱形主梁結(jié)構(gòu)疲勞壽命估算方法的可行性。
[Abstract]:Bridge crane, as one of the necessary special equipments in modern industrial production and lifting transportation, has been widely used in railway transportation, iron and steel chemical industry, port and wharf, logistics and other departments and places. However, bridge crane is the special equipment with the most hidden risk factors and the greatest chance of casualties in large mechanical equipment. The frequent crane accidents at home and abroad cause extremely serious personal injury and property losses. According to a large number of statistical data, the most common and serious of these accidents is the fatigue failure of welded box girder structure of bridge crane, which is characterized by fatigue cracks. The box girder structure of bridge crane is its main bearing member. The main failure form of bridge crane is fatigue fracture of main beam under random load. The rupture of the main beam means the end of the life of the bridge crane. Therefore, the study of fatigue crack propagation law and the prediction of residual fatigue life of box girder of bridge crane in service can prevent the occurrence of fatigue fracture failure accident, and for the design and manufacture of bridge crane, the fatigue crack propagation law of the box girder structure and the prediction of the residual fatigue life of the box main girder can be prevented. Use and maintenance have important guiding significance. Based on the modern fatigue cumulative damage theory, this paper analyzes the fatigue failure characteristics and influencing factors of box girder of bridge crane, and uses ANSYS finite element analysis software to analyze the structure of box girder of bridge crane. The dangerous site is determined and fatigue analysis and residual life estimation are carried out. In addition, combined with the theory of fracture mechanics, the residual fatigue life of box girder structure with fatigue cracks is predicted, which can improve the reliability of bridge crane and prolong its service life. It is of great significance to improve the production efficiency of crane in engineering practice. Firstly, the finite element model of the box girder structure of the bridge crane is established, and five typical working conditions of the crane are selected. In the condition of fatigue load distribution similar to the actual working conditions, the finite element simulation analysis of the box girder structure without defects is carried out, and the stress, displacement deformation and safety factor distribution of the box girder structure under each working condition are obtained. The maximum position of stress value and displacement and deformation of box girder structure and the position with lowest safety factor are determined. Secondly, the life analysis module of ANSYS finite element analysis software is used to estimate the design life of the bridge crane girder structure with initial cracks, and the simulation results are analyzed. The distribution of safety factor and fatigue life of box girder structure with initial cracks are obtained under the approximate actual working conditions. The distribution of fatigue life in various parts of box girder structure is directly reflected. Finally, using the method of linear elastic fracture mechanics, the fatigue propagation life of the end beam of the bridge crane and the residual life of the box girder structure are estimated. The relationship between the fatigue crack length at the end web of the box girder structure and the cycle times of the crane is plotted. By comparing the results of finite element simulation with the measured results, it is found that the two are in good agreement with each other, which proves the feasibility of the fatigue life estimation method of the box girder structure.
【學(xué)位授予單位】：太原科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類號(hào)】：TH215

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