【正文】 ........................................................... 13 不銹鋼與紫銅焊接工藝 .................................................................................. 13 薄壁不銹鋼與 紫銅焊接操作 .......................................................................... 16 本章小結(jié) .................................................................................................................... 17 第 3 章 有限元模型的建立 .................................................................................................... 19 幾何模型的建立 ........................................................................................................ 19 單元類型的確定 ........................................................................................................ 21 材料的熱物理性能和力學(xué)性能參數(shù) ........................................................................ 23 網(wǎng)格的劃分 ................................................................................................................ 27 單元生死技術(shù) ............................................................................................................ 29 熱源模型的選取 ........................................................................................................ 30 本章小結(jié) .................................................................................................................... 31 第 4 章 焊接溫度場模擬及結(jié)果分析 .................................................................................... 33 焊接溫度場數(shù)值模擬理論 ........................................................................................ 33 溫度場模擬邊界條件的確定 .................................................................................... 34 熱源的加載和移動 .................................................................................................... 35 溫度場求解 ................................................................................................................ 37 溫度場后處理以及結(jié)果分析 .................................................................................... 37 ANSYS 后處理器 ............................................................................................ 37 溫度場結(jié)果分析 .............................................................................................. 38 本章小結(jié) .................................................................................................................... 45 第 5 章 焊接應(yīng)力場計(jì)算及結(jié)果分析 .................................................................................... 47 焊接應(yīng)力場數(shù)值模擬理論 ........................................................................................ 47 焊接應(yīng)力場塑性準(zhǔn)則 ...................................................................................... 47 焊接熱彈塑性有限元法 .................................................................................. 47 邊界條件的確定 ........................................................................................................ 48 應(yīng)力場求解 ................................................................................................................ 50 應(yīng)力場分析 ................................................................................................................ 51 VonMises 應(yīng)力 ................................................................................................ 51 軸向殘余應(yīng)力 .................................................................................................. 56 徑向殘余應(yīng)力 .................................................................................................. 57 切向殘余應(yīng)力 .................................................................................................. 58 焊后變形分析 ............................................................................................................ 59 本章小結(jié) .................................................................................................................... 61 第 6 章 結(jié) 論 ........................................................................................................................ 63 參 考 文 獻(xiàn) ............................................................................................................................ 67 致 謝 .................................................................................................................................. 71 在校期間取得的研究成果 ........................................................................ 錯誤 !未定義書簽。 TIG welding。 根據(jù)對焊件焊后應(yīng)力場、焊件焊后變形的分析，本文對焊件進(jìn)行了強(qiáng)度和變形校核，校核結(jié)果為：焊件合格，焊接可行。建議在焊接時嚴(yán)格控制熔池溫度、電弧大小以及氬氣流量。這使得焊縫兩側(cè)基體金屬熔化程度不一致，可能導(dǎo)致焊縫成形不良。 本文通過 ANSYS 軟件 對其 焊接過程進(jìn)行 了 模擬， 得到了薄壁不銹鋼與薄壁紫銅 焊接過程中的溫度場、應(yīng)力 場分布，并依據(jù)模擬結(jié)果對焊接過程中可能出現(xiàn)的缺陷進(jìn)行了分析 。不銹鋼與紫銅的焊接屬于異種金屬焊接，兩者的物理性質(zhì)差異很大，因而兩者的焊接難度較大，在氬弧焊過程中易產(chǎn)生各種缺陷。具體結(jié)論和建議如下： 一、 由于紫銅散熱比不銹鋼快，因此 薄壁不銹鋼和薄壁紫銅 焊接過程中兩管的溫度場分布極不均衡。因此，在焊接結(jié)合處會有較大的變形，其內(nèi)部可能會出現(xiàn)較多的裂紋。建議焊前對焊件采取反應(yīng)力、反變形措施。 Finally, the temperature and stress field indirect coupling method is used to simulate the welding stress field by applying the results of temperature field analysis as temperature loads on the model. After that, the results of stress field simulation are analyzed. Based on the simulation results of welding temperature and stress field, the quality defects of thinwalled stainless steel with copper that may occur during the TIG welding and cooling process are analyzed and some remendations are made accordingly. Specific conclusions and remendations are as follows: Firstly, because the heat transferring of copper is faster than stainless steel, so temperature field distribution of thinwalled stainless steel and copper tubes during the welding process is extremely uneven. This may leads to molten inconsistency of base metal on both sides and may cause poor weld seam. It is remended that the welding arc is slightly partial to copper, in case of the excessive heating of stainless steel. Secondly, at the end of cooling, large residual stress that is 253MPa is remained in the junction area among starting and ending position of welding, close to the y