【摘要】：鋁合金十字接頭被廣泛應(yīng)用于高鐵列車的轉(zhuǎn)向架的焊接中,由于長(zhǎng)時(shí)間承受循環(huán)載荷的作用,所以容易發(fā)生疲勞斷裂問(wèn)題,本文針對(duì)7N01鋁合金材料十字接頭為研究對(duì)象,分別針對(duì)疲勞萌生和擴(kuò)展兩個(gè)階段進(jìn)行研究,通過(guò)實(shí)驗(yàn)和有限元相結(jié)合的方法計(jì)算疲勞裂紋萌生和疲勞裂紋擴(kuò)展壽命。通過(guò)對(duì)7N01母材和焊縫材料進(jìn)行低周疲勞實(shí)驗(yàn),擬合母材和焊縫的循環(huán)應(yīng)變幅-壽命曲線,通過(guò)對(duì)實(shí)驗(yàn)結(jié)果的分析發(fā)現(xiàn),在載荷水平較低,壽命較長(zhǎng)的情況下,彈性應(yīng)變對(duì)試件的疲勞過(guò)程的影響大,塑性應(yīng)變影響很小,隨著載荷的增加,塑性應(yīng)變所占的比重會(huì)快速增加,當(dāng)載荷水平在較高時(shí),此時(shí)塑性應(yīng)變起處于主要的地位,對(duì)疲勞過(guò)程起到了主要推進(jìn)過(guò)程;通過(guò)有限元的方法模擬十字接頭的應(yīng)力分布狀態(tài),發(fā)現(xiàn)應(yīng)力集中位置和實(shí)際疲勞過(guò)程中的開裂位置吻合,并計(jì)算獲得疲勞失效位置的應(yīng)力集中系數(shù)�？紤]到焊接過(guò)程是一個(gè)快速加熱又快速冷卻的過(guò)程,分析了焊接接頭殘余應(yīng)力在循環(huán)過(guò)程中的松弛情況,同時(shí)考慮到不對(duì)稱載荷的影響,對(duì)循環(huán)應(yīng)力幅-壽命關(guān)系式加以修正;求解以循環(huán)應(yīng)力-應(yīng)變方程和Neuber雙曲線方程構(gòu)成的方程組的解求出局部應(yīng)變,在將其代入修正后的循環(huán)應(yīng)變-壽命公式,求得試件在焊趾處和焊縫處的疲勞裂紋萌生壽命。引入了權(quán)函數(shù)的思想,推導(dǎo)出板邊裂紋應(yīng)力強(qiáng)度因子的表達(dá)式;分別利用有限元計(jì)算法,膜應(yīng)力、彎曲應(yīng)力法和節(jié)點(diǎn)力法,對(duì)十字接頭焊趾處進(jìn)行應(yīng)力場(chǎng)分布求解,結(jié)合權(quán)函數(shù)導(dǎo)出的應(yīng)力強(qiáng)度因子公式,計(jì)算出試件的應(yīng)力場(chǎng)強(qiáng)度因子,通過(guò)對(duì)結(jié)果的分析發(fā)現(xiàn),節(jié)點(diǎn)力法所求的應(yīng)力場(chǎng)強(qiáng)度因子隨裂紋長(zhǎng)度的分布變化更符合真實(shí)的結(jié)果;將所求的應(yīng)力場(chǎng)強(qiáng)度因子帶入Pairs公式求解試件的疲勞擴(kuò)展壽命;介紹了結(jié)構(gòu)應(yīng)力法的原理,并利用結(jié)構(gòu)應(yīng)力法求解十字接頭的疲勞總壽命;將結(jié)構(gòu)應(yīng)力法求得的疲勞總受壽命,分階段求得的疲勞萌生壽命和和擴(kuò)展壽命相加的疲勞總壽命以及實(shí)驗(yàn)中記錄的試件疲勞壽命,三者分析比較,發(fā)現(xiàn)三者基本上能較好的吻合,從而驗(yàn)證了所用的計(jì)算方法的合理性。
[Abstract]:The aluminum alloy cross joint is widely used in the welding of the bogie of the high-speed rail train, and the fatigue fracture is easy to occur due to the long-time bearing of the cyclic load. The cross joint of the 7N01 aluminum alloy material is the research object, The fatigue crack initiation and fatigue crack propagation life were calculated by the combination of experiment and finite element method. By carrying out low-cycle fatigue experiment on the 7N01 base material and the welding seam material, the cycle of the base material and the welding line should be fitted with an amplitude-life curve, and the influence of the elastic strain on the fatigue process of the test piece is large under the condition that the load level is lower and the service life is long by the analysis of the experimental result, The influence of plastic strain is very small, with the increase of load, the specific gravity of plastic strain will increase rapidly, and when the load level is higher, the plastic strain is in the main position at this time, and the fatigue process plays a major advance. The stress distribution state of the cross joint is simulated by the finite element method, and the stress concentration position and the crack position in the actual fatigue process are found to coincide with each other, and the stress concentration coefficient of the fatigue failure position is calculated. Considering that the welding process is a rapid heating and rapid cooling process, the relaxation of the residual stress of the welded joint during the cycle is analyzed, and the influence of the asymmetric load is taken into account, and the cyclic stress amplitude-life relation is corrected. The local strain is obtained by solving the solution of the equations of the cyclic stress-strain equation and the Neuber hyperbolic equation, and the fatigue crack initiation life of the test piece at the toe and the weld is obtained after the modified cyclic strain-life formula is substituted into the modified cyclic strain-life formula. The method of weight function is introduced, and the expression of the stress intensity factor of the crack stress of the plate edge is derived. The stress field distribution and the stress intensity factor formula derived from the weight function are calculated by using the finite element method, the film stress, the bending stress method and the node force method. The stress field intensity factor of the test piece is calculated. Through the analysis of the result, the stress field strength factor obtained by the node force method is more consistent with the real result with the distribution change of the crack length, and the obtained stress field strength factor is taken into the Pairs formula to solve the fatigue extension life of the test piece; The principle of the structural stress method is introduced, and the fatigue life of the cross joint is solved by the structural stress method. The fatigue life, the fatigue life and the fatigue life of the fatigue life and the fatigue life of the test piece recorded in the experiment are calculated by the structural stress method. The analysis and comparison show that the three are basically good agreement, thus the rationality of the calculation method used is verified.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG407

【參考文獻(xiàn)】

相關(guān)期刊論文 前5條

1 陳景杰;黃一;劉剛;;基于奇異元計(jì)算分析裂紋尖端應(yīng)力強(qiáng)度因子[J];中國(guó)造船;2010年03期

2 肖濤;左正興;;虛擬裂紋閉合法在結(jié)構(gòu)斷裂分析中的應(yīng)用[J];計(jì)算力學(xué)學(xué)報(bào);2008年S1期

3 楊遇春;;鋁和軌道交通運(yùn)輸[J];中國(guó)工程科學(xué);2008年05期

4 田常海,任明法,陳浩然;復(fù)合型裂紋斷裂和擴(kuò)展速率試驗(yàn)夾具及裂紋長(zhǎng)度測(cè)量方法[J];實(shí)驗(yàn)力學(xué);2001年01期

5 劉靜安;;鋁材在鐵道車輛中的應(yīng)用(開發(fā)鋁材新品種·擴(kuò)大鋁材新用途·拓寬鋁材新市場(chǎng)系列文章之十二)[J];輕合金加工技術(shù);1993年06期

，

本文編號(hào)：2488061