發(fā)布時間：2018-05-14 01:21

  本文選題：底架結(jié)構(gòu) + 疲勞累積損傷理論��； 參考：《武漢理工大學(xué)》2011年碩士論文

【摘要】：輪胎式起重機采用的是周期性間歇作業(yè),經(jīng)常會頻繁的起升或者下降以及起動和制動。由于其工作速度高,工況復(fù)雜而且比較繁重,受循環(huán)往復(fù)的交變載荷,因而容易產(chǎn)生金屬結(jié)構(gòu)件的疲勞開裂,對正常的安全生產(chǎn)造成嚴重威脅。國內(nèi)外對起重機的疲勞破壞作了不少研究,但是大多涉及到港口的橋架型起重機,這種類型的起重機通常都沒有回轉(zhuǎn)機構(gòu),而回轉(zhuǎn)作業(yè)會使起重機的作業(yè)條件更惡劣,由于產(chǎn)生的應(yīng)力幅更容易發(fā)生疲勞破壞；也有少數(shù)涉及到門座式起重機的疲勞研究,但是門座式起重機由于使用了臂架自重平衡系統(tǒng),可以全幅度變幅和回轉(zhuǎn)作業(yè),而輪胎式起重機只能按照起重能力表在不同的幅度下有其相對的額定起重量。鑒于此,有必要對港口的輪胎式起重機做一個疲勞方面的分析研究。 底架是輪胎式起重機的重要的承載結(jié)構(gòu)件,因工況比較繁重以及受力狀況復(fù)雜而易出現(xiàn)疲勞破壞和裂紋。在以前的輪胎式起重機設(shè)計中,主要按照經(jīng)驗設(shè)計和靜強度設(shè)計方法,通常采用選擇較大的許用安全系數(shù)或者選擇提高其材料的許用應(yīng)力兩種辦法來減少結(jié)構(gòu)破壞,而這樣就必須增加板厚或采用高強度鋼,但是這樣緊緊是提高了構(gòu)件的靜強度,仍然有可能發(fā)生結(jié)構(gòu)疲勞破壞,因為疲勞破壞不同于靜力破壞。疲勞裂紋通常是先在結(jié)構(gòu)危險點的局部區(qū)域內(nèi)萌生,然后裂紋擴展直至發(fā)生結(jié)構(gòu)斷裂。因此,必須采取合理的方法降低危險點的峰值應(yīng)力,或者提高危險點的局部區(qū)域材料強度,才能提高其疲勞強度,從而確保輪胎式起重機安全有效的運行使用。 本文首先介紹了疲勞的一些基本概念、疲勞強度理論以及本文所用到的三種有限元分析軟件；然后采用MSC.Patran對進行輪胎式起重機底架結(jié)構(gòu)建模,合理分析了載荷情況和加載方式,并對模型局部不斷調(diào)整,然后使用MSC.Nastran進行靜力分析,驗算相關(guān)的靜強度剛度；以《起重機設(shè)計規(guī)范》為標(biāo)準(zhǔn),對底架結(jié)果進行多種工況下的靜力分析結(jié)果,按步驟進行疲勞強度校核,發(fā)現(xiàn)可能的疲勞點,從而指導(dǎo)設(shè)計改正；通過對起重機底架典型工況的瞬態(tài)分析得到相關(guān)的應(yīng)力譜,再結(jié)合查詢得到S-N曲線,利用MSC.Fatigue對底架結(jié)構(gòu)進行了全壽命分析,得出底架結(jié)構(gòu)的全壽命云圖,并作出相關(guān)分析。
[Abstract]:Tyre cranes use periodic intermittent operations, often frequent hoisting or dropping, starting and braking. Because of its high working speed, complex and heavy working conditions, and subjected to cyclic alternating load, it is easy to produce fatigue cracking of metal structure, which poses a serious threat to normal safety production. Many researches have been done on the fatigue failure of cranes at home and abroad, but most of them involve bridge cranes in ports, which usually do not have rotary mechanism, and rotary operation will make the working conditions of cranes worse. Because the stress amplitude generated is more prone to fatigue failure; there are also a few related to the fatigue study of gantry cranes, but the gantry cranes can vary amplitude and rotate in full amplitude because of the use of the jib self-weight balance system. The tire crane can only have its relative rated lifting weight according to the lifting capacity table at different ranges. In view of this, it is necessary to do a fatigue analysis of the port tire crane. Chassis is an important bearing structure of tire crane. Fatigue failure and crack are easy to occur because of heavy working conditions and complicated mechanical conditions. In the previous design of tire crane, according to the experience design and static strength design method, two methods are usually adopted to reduce the structural damage, such as choosing a larger allowable safety factor or choosing to increase the allowable stress of the material. In this way, the thickness of plate or high strength steel must be increased, but the static strength of the member can be improved so that the fatigue failure of the structure is still possible, because the fatigue failure is different from the static failure. The fatigue crack usually originates in the local region of the dangerous point of the structure, and then the crack propagates until the structure breaks. Therefore, it is necessary to adopt reasonable methods to reduce the peak stress of the dangerous point or to increase the local material strength of the dangerous point in order to improve the fatigue strength and ensure the safe and effective operation of the tyre crane. This paper first introduces some basic concepts of fatigue, fatigue strength theory and three kinds of finite element analysis software used in this paper, and then uses MSC.Patran to model the structure of tire crane chassis, and reasonably analyzes the load situation and loading mode. The model is adjusted locally, and then static analysis is carried out by using MSC.Nastran to calculate the relative static strength stiffness, and the results of static analysis under various working conditions are carried out on the basis of "Crane Design Code" as the standard. The fatigue strength is checked according to the steps, the possible fatigue point is found, and the design correction is guided. The related stress spectrum is obtained by transient analysis of the typical working conditions of the crane chassis, and then the S-N curve is obtained by combining with the query. The whole life of the underframe structure is analyzed by MSC.Fatigue, and the whole life cloud diagram of the underframe structure is obtained, and the correlation analysis is made.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：TH213.6

【引證文獻】

相關(guān)碩士學(xué)位論文 前1條

1 李鳳玲;地下裝載機動強度分析研究[D];河北工程大學(xué);2012年

，

本文編號：1885693