【正文】 、密度或由這幾個參數(shù)聯(lián)合表示的熱擴散率，是影響焊接溫度場分布的主要物理參數(shù)。焊接應力的產(chǎn)生和發(fā)展是一個隨加熱與冷卻而變化的材料熱彈塑性，應力應變動態(tài)過程。 產(chǎn)生焊接殘余應力的情況可以應用經(jīng)驗法則來判斷：熱應力為最后冷卻的區(qū)域，焊接拉伸應力為主，焊接壓應力是在相變的應力為主時。 焊接殘余應力概述 焊接殘余應力的概念焊件在焊接過程中，熱應力、相變應力、 加工應力等超過屈服極限（Yield strength），以致冷卻后焊件中留有未能消除的應力，這樣，焊接冷卻后的殘余在焊件中的宏觀應力稱為殘余焊接應力，焊接應力包括沿焊縫長度方向的縱向焊接應力，垂直于焊縫長度方向的橫向焊接應力和沿厚度方向的焊接應力。綜合上面的各種原因，對其的研究以逐步的成為結(jié)構(gòu)領域的重點課題[3]。殘余應力的峰值甚至可能達到或超過材料的屈服極限,當這些焊接構(gòu)件投入使用時,它們所受載荷引起的工作應力與其內(nèi)部的焊接殘余應力相疊加,將導致焊接構(gòu)件產(chǎn)生二次變形和焊接殘余應力的重新分布,是的其在鋼材的保證穩(wěn)定性能的尺寸和它的剛度方面的能力下降了[5]。焊接的技術(shù)核心通常是構(gòu)件局部加熱熔化,隨后是連續(xù)的冷卻[3]。 on the flange width to maintain the same in the case, change the width of lower flange, with the upper and lower flange width ratio decreases, the upper and lower flange and web an increase in residual stress, residual stress in the upper and lower flange distribution line on the trends and values, the residual pressive stress in the upper and lower webs value is also consistent, gradient decreases, the residual stress in the uniaxial symmetry crosssection on the distribution curve residual stress tends to biaxial symmetry classic crosssection distribution. Uniaxial symmetry by beam welders residual stress simulation, optimization for the future design of welded structures provide an important basis.Keywords: Welding residual stress。 uniaxial symmetry beams with web biaxial residual stress distribution curve symmetrical crosssection of different web residual stress distribution curve, the residual stress at both ends of the web is not as symmetrical, close to the lower flange side of the residual pressive stress is less than one near the top flange side of the residual pressive stress, trapezoidal distribution. This is due to the different upper and lower flange width of the temperature distribution caused by different, resulting in asymmetric distribution of residual stress.By studying the beam flange width to thickness ratio, web thickness ratio, the upper and lower flange width and other parameters of the uniaxial symmetry than the crosssection shows the residual stress effects: on the flange width to maintain the same in the case, change the thickness of the flange, with the flange width to thickness ratio decreases, the upper and lower flange and web of residual stress gradually decreases with increase in tension zone trends。通過對單軸對稱焊接工字梁殘余應力的模擬計算，為以后焊接結(jié)構(gòu)的優(yōu)化設計提供重要依據(jù)。這是由于上下翼緣寬度不同造成溫度場分布不同，從而導致殘余應力的不對稱分布。因此，本文對單軸對稱焊接工字梁的殘余應力進行研究，為其整體穩(wěn)定設計提供參考。單軸對稱焊接工字梁殘余應力研究摘要：焊接殘余應力是影響梁整體穩(wěn)定的重要因素，在梁整體穩(wěn)定設計中應該考慮殘余應力對梁的影響。我國現(xiàn)行鋼結(jié)構(gòu)規(guī)范(GB500172003 )中只提出了雙軸對稱焊接工字梁的整體穩(wěn)定系數(shù)，其他截面只能借用，合適與否，需要進一步的證明。本文以焊接過程的有限元理論為基礎，總結(jié)前人的經(jīng)驗和成果，應用大型通用軟件ANSYS對焊接過程進行三維數(shù)值模擬，首先采用間接法，對現(xiàn)有單雙軸對稱截面焊接工字梁實驗進行模擬，以生熱率的形式施加熱源，同時通過“控制單元的生死”有效模擬了焊縫金屬的填充、熔化和凝固過程，有限元計算結(jié)果與試驗結(jié)果比較吻合，證實了計算模型的有效性，為用有限元分析焊接工字形截面梁殘余應力提供了一種方法，并對單雙軸對稱截面焊接工字梁殘余應力進行計算對可知：單軸對稱截面梁上下翼緣殘余應力分布曲線與雙軸對稱截面上下翼緣殘余應力分布區(qū)曲線類似，呈拋物線分布，但單軸對稱截面上下翼緣殘余應力在數(shù)值上并不完全相同，殘余壓應力在數(shù)值上有一定差別；單軸對稱截面梁腹板殘余應力分布曲線與雙軸對稱截面腹板殘余應力分布曲線不同，腹板兩端的殘余應力并不成對稱分布，靠近下翼緣一側(cè)的殘余壓應力要小于靠近上翼緣一側(cè)的殘余壓應力，呈梯形分布。通過研究梁翼緣寬厚比、腹板高厚比、上下翼緣寬度比等參數(shù)對單軸對稱截面殘余應力影響可知：在保持上翼緣寬度不變的情況下，改變翼緣的厚度，隨著翼緣寬厚比逐漸減小，上下翼緣和腹板的殘余應力逐漸減小，受拉區(qū)有增大趨勢；在保持腹板厚度不變的情況下，改變腹板的高度，隨著腹板高厚比逐漸增大，上下翼緣的殘余應力逐漸減小，受拉區(qū)逐漸增大，腹板上下殘余拉應力逐漸減小，但是隨著腹板面積的逐漸加大，腹板上下殘余壓應力逐漸加大，受壓區(qū)有增大趨勢；在保持上翼緣寬度不變的情況下，改變下翼緣的寬度，隨著上下翼緣寬度比逐漸減小，上下翼緣和腹板殘余應力有所增加，上下翼緣殘余應力在分布趨勢和數(shù)值上趨于一致，腹板上下殘余壓應力在數(shù)值上也趨于一致，梯度逐漸減小，單軸對稱截面殘余應力在分布曲線上趨于雙軸對稱截面殘余應力經(jīng)典分布。關(guān)鍵詞：焊接殘余應力；數(shù)值模擬；單軸對稱工字梁；生死單元 AbstractWelding residual stress is the effect of the whole stability of the important factors beam, the overall stability in beam design should be considered in the influence of the residual stress of the beam. Our current steel structure specifications (GB500172003) only put forward the dual axle welding symmetrically strander overall stability coefficient of the beam, and other section can only borrow, if appropriate, need to be further proof. Therefore, this paper single beam welding of axisymmetric encountered residual stress in research, for its overall stability provides reference for the design.In this paper, the finite element welding process based on the theory, summed up the experiences and results, a large generalpurpose application software ANSYS threedimensional numerical simulation of welding process, first using the indirect method, symmetrical crosssection of existing singleaxis beam welders experiment simulation, in order to impose the form of heat rate of heat at the same time through the control unit of the life and death Effective simulation of the weld metal filling, melting and solidification process, finite element analysis good agreement with the experimental results, confirming the effective putational model sex, for the use of finite element analysisshaped crosssection beam welders provide a method of residual stress, and singleaxis symmetrical crosssection beam welders for residual stress calculation shows that: the upper and lower flange section beam axis symmetrical residual stress distribution curve symmetrical crosssection from top to bottom flange with the biaxial residual stress distribution curve is similar to a parabolic distribution, but the uniaxial symmetry section of the upper and lower flange residual stress are not identical in value, the residual pressive stress there are some differences in values。 web thickness while maintaining the same circumstances, to change the height of the web, with the abdominal plate thickness ratio increases, the upper and lower flange of the residual stress gradually decreases gradually increasing tension zone, the web up and down the residual tensile stress decreases, but with the gradual increase in the area of ??web, web up and down the residual stress gradually increased, there is increasing trend of pression zone。 Numerical simulation；Monosymmetric Isection beams；Birthdeath element碩士研究生學位論文 第一章 緒論 5第一章 緒論 引言近年來，單軸對稱焊接工字梁在工程中的應用越來越廣泛，與傳統(tǒng)的雙軸對稱焊接工字梁相比，其上下翼緣的強度都得到了充分的發(fā)揮，承載能力明顯提高，從而節(jié)省了用鋼量，在鋼材價格大幅上漲的今天更凸顯其應用的價值[12]，鋼結(jié)構(gòu)的承載力一直是結(jié)構(gòu)領域關(guān)注的焦點，影響單軸對稱焊接工字梁承載力的因素很多，焊接殘余應力是其中一個非常關(guān)鍵的環(huán)節(jié)。鋼材在焊接和冷卻的過程中, 其局部形成一個很不均勻的溫度場, 由于膨脹和收縮的程度和速度不同, 溫度場內(nèi)各部分鋼材的變形相互