本文選題：前橋　切入點(diǎn)：強(qiáng)度分析　出處：《山東理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：轉(zhuǎn)向橋作為汽車底盤的重要部件之一,所受載荷大,應(yīng)力狀況復(fù)雜,是決定汽車安全性能的關(guān)鍵部件之一。目前,車橋的疲勞損傷問題日益突出,疲勞破壞已經(jīng)成為前橋的主要失效形式之一。因此,前橋的強(qiáng)度和疲勞對(duì)汽車安全行駛具有重要影響。本文對(duì)某重型載貨汽車的前橋進(jìn)行了有限元分析,檢驗(yàn)其強(qiáng)度和壽命是否滿足要求,為其設(shè)計(jì)生產(chǎn)和結(jié)構(gòu)改進(jìn)提供參考;還針對(duì)含損傷裂紋的前橋疲勞進(jìn)行了分析。主要的研究工作如下:(1)對(duì)前橋進(jìn)行多種工況的強(qiáng)度分析。依據(jù)前橋的結(jié)構(gòu)和受力特點(diǎn),對(duì)其進(jìn)行合理簡(jiǎn)化,建立有限元模型,分析前橋處于滿載彎曲、制動(dòng)和轉(zhuǎn)彎三種工況時(shí)的受力情況,確定不同工況下的載荷和約束,對(duì)前梁進(jìn)行強(qiáng)度分析。結(jié)果表明,三種工況下的最大應(yīng)力均沒有超過材料的屈服極限,該前橋滿足強(qiáng)度方面的要求。(2)建立S-N曲線,選取第一主應(yīng)力為應(yīng)力分量對(duì)前梁進(jìn)行疲勞壽命分析,并采用Gerber平均應(yīng)力修正法對(duì)其進(jìn)行修正,得到前梁的疲勞壽命低于標(biāo)準(zhǔn)JB/T50109-1998規(guī)定的80萬次;并將計(jì)算結(jié)果與試驗(yàn)結(jié)果進(jìn)行比較,進(jìn)一步驗(yàn)證有限元分析的可靠性。(3)針對(duì)前橋的結(jié)構(gòu)和應(yīng)力分布對(duì)前橋進(jìn)行結(jié)構(gòu)改進(jìn),再進(jìn)行疲勞計(jì)算。改進(jìn)后前梁的疲勞壽命滿足了標(biāo)準(zhǔn)要求,并且各工況下的應(yīng)力都有所減小;然后對(duì)優(yōu)化后的模型進(jìn)行模態(tài)分析,得到前梁前6階模態(tài)的固有頻率和振型。經(jīng)過分析,前梁不會(huì)由于不平路面的激振而發(fā)生共振,顯示了結(jié)構(gòu)改進(jìn)的合理性。(4)在強(qiáng)度和疲勞分析的基礎(chǔ)上,研究裂紋的各種參數(shù)對(duì)前橋疲勞壽命的影響規(guī)律。根據(jù)應(yīng)力計(jì)算劃定前橋的危險(xiǎn)區(qū),在危險(xiǎn)區(qū)域?qū)α鸭y進(jìn)行參數(shù)化建模,建立橢圓形表面裂紋;調(diào)整裂紋的方向、尺寸等參數(shù),對(duì)含不同裂紋的前梁進(jìn)行疲勞分析,統(tǒng)計(jì)前梁的疲勞壽命。對(duì)統(tǒng)計(jì)的數(shù)據(jù)進(jìn)行處理,分析前梁疲勞壽命隨著裂紋各個(gè)參數(shù)的變化趨勢(shì),總結(jié)其對(duì)前梁疲勞壽命的影響。還對(duì)前梁含有多裂紋的情況進(jìn)行了研究,分析裂紋間的間距對(duì)疲勞壽命的影響。上述研究不僅得到了該型號(hào)前橋的強(qiáng)度和疲勞情況,而且還得到了裂紋損傷對(duì)前橋疲勞壽命的影響情況。這為企業(yè)的實(shí)際生產(chǎn)提供了一定的理論依據(jù),并且對(duì)預(yù)測(cè)車橋疲勞故障減少疲勞事故,起到一定的指導(dǎo)作用,而且也為其它含損傷裂紋結(jié)構(gòu)的疲勞分析提供了一種值得借鑒的方法。
[Abstract]:As one of the important parts of automobile chassis, steering bridge is one of the key parts of automobile safety performance, which is subjected to heavy load and complicated stress condition. At present, the fatigue damage problem of vehicle bridge is becoming more and more serious. Fatigue failure has become one of the main failure forms of the front axle. Therefore, the strength and fatigue of the front axle have an important effect on the safe driving of the vehicle. In this paper, the finite element analysis of the front axle of a heavy-duty truck is carried out. Test its strength and life to meet the requirements, for its design and production and structural improvement to provide a reference; The fatigue of front axle with damage crack is analyzed. The main research work is as follows: 1) the strength of front axle under various working conditions is analyzed. According to the structure and stress characteristics of front axle, the fatigue of front axle is reasonably simplified, and the finite element model is established. The stress of front axle under three conditions of full load bending, braking and turning is analyzed, the load and constraint under different working conditions are determined, and the strength of front girder is analyzed. The maximum stress of the front axle does not exceed the yield limit of the material under three working conditions. The front axle satisfies the strength requirement. The S-N curve is established. The first principal stress is selected as the stress component to analyze the fatigue life of the front beam. The fatigue life of the front beam is 800,000 times lower than that of the standard JB/T50109-1998, and the calculated results are compared with the test results. Further verify the reliability of finite element analysis. 3) improve the front axle structure and stress distribution, and then carry out fatigue calculation. The improved fatigue life of the front beam meets the standard requirements. Then the modal analysis of the optimized model is carried out to get the natural frequency and mode shape of the first six modes of the front beam. After analysis, the front beam will not resonate because of the vibration induced by the uneven road surface. The rationality of structural improvement is shown. (4) on the basis of strength and fatigue analysis, the influence of crack parameters on fatigue life of front axle is studied, and the dangerous zone of front axle is determined according to stress calculation. In the dangerous area, the crack is parameterized, the elliptical surface crack is established, the direction and size of the crack are adjusted, the fatigue life of the front beam with different cracks is analyzed, and the fatigue life of the front beam is calculated. The change trend of fatigue life of front beam with each parameter of crack is analyzed, and the influence of fatigue life of front beam on fatigue life of front beam is summarized. The influence of crack spacing on fatigue life is analyzed. Moreover, the influence of crack damage on fatigue life of front axle is obtained, which provides a theoretical basis for the actual production of enterprises, and plays a certain guiding role in predicting the fatigue failure of vehicle and bridge to reduce fatigue accidents. It also provides a useful method for fatigue analysis of other structures with damaged cracks.
【學(xué)位授予單位】：山東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U441.4

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 謝海;ZL60裝載機(jī)驅(qū)動(dòng)橋總成結(jié)構(gòu)分析研究[D];浙江理工大學(xué);2013年

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本文編號(hào)：1578271