【摘要】：針對鋁合金焊縫性能低于母材、現(xiàn)有成形極限分析方法不適宜分析鋁合金攪拌摩擦焊板材成形極限的現(xiàn)狀,提出了一種基于二次多項式新本構模型的鋁合金拼焊板成形極限理論模型。核心思想為利用材料自身的性能差異替代經(jīng)典M-K理論模型的溝槽假設。針對鋁合金硬化指數(shù)低、冪指數(shù)回歸精度差的問題,將二次多項式新本構模型應用于M-K理論模型,最終建立了適合于鋁合金攪拌摩擦焊拼焊板的成形極限理論預測模型。對鋁合金攪拌摩擦焊板材進行了成形極限實驗,并通過XJTUDIC三維數(shù)字散斑應變變形測量系統(tǒng)實時測量變形過程中的應變值,得到了鋁合金攪拌摩擦焊拼焊板的實驗成形極限圖。最后對實驗結果和理論分析結果進行了對比。相比傳統(tǒng)的冪指數(shù)本構模型,二次多項式對應力-應變曲線的回歸,無論在初試屈服階段或后期變形階段均有很好的吻合精度。冪指數(shù)最大擬合誤差超過12%,而二次多項式的擬合誤差小于1%,二次多項式回歸模型能很好地擬合鋁合金攪拌摩擦焊接接頭的應力-應變關系;采用二次多項式本構關系的理論模型能很好地預測鋁合金攪拌摩擦焊板材的成形極限,第一主應變的預測誤差小于0.01;而冪指數(shù)理論模型則導致平面應變狀態(tài)下的極限應變預測結果明顯不準,在相同應變路徑下第一主應變的預測誤差達0.14。
[Abstract]:As the welding performance of aluminum alloy is lower than that of base metal, the present forming limit analysis method is not suitable for analyzing the forming limit of aluminum alloy friction stir welding sheet. Based on the new constitutive model of quadratic polynomial, a theoretical model of forming limit of aluminum TWF is proposed. The core idea is to substitute the grooves hypothesis of the classical M-K theory model with the performance difference of the material itself. Aiming at the problems of low hardening index of aluminum alloy and poor precision of power exponent regression, a new constitutive model of quadratic polynomial is applied to M-K theoretical model. Finally, a theoretical prediction model of forming limit for friction stir welding of aluminum alloy is established. The forming limit test of aluminum alloy friction stir welding plate was carried out, and the strain value in the process of deformation was measured in real time by using XJTUDIC 3D digital speckle strain deformation measurement system, and the experimental forming limit diagram of aluminum alloy friction stir welding TWW sheet was obtained. Finally, the experimental results are compared with the theoretical analysis results. Compared with the traditional power exponent constitutive model, the regression of the quadratic polynomial to the stress-strain curve has a good accuracy in both the initial yield stage and the later deformation stage. The maximum fitting error of power exponent is more than 12, but the fitting error of quadratic polynomial is less than 1. The quadratic polynomial regression model can fit the stress-strain relationship of friction stir joint of aluminum alloy. The theoretical model of quadratic polynomial constitutive relation is used to predict the forming limit of friction stir welding sheet. The prediction error of the first principal strain is less than 0.01, while that of the power exponent model leads to the obvious inaccuracy of the prediction results of the limit strain in the plane strain state, and the prediction error of the first principal strain under the same strain path is 0.14.
【作者單位】： 哈爾濱工業(yè)大學(威海);威海北洋電氣集團股份有限公司;
【基金】：國家自然科學基金項目Nos.51405102和51475121 中國博士后科學基金項目No.2015M570286 中央高校基本科研業(yè)務費專項資金項目No.HIT.NSRIF.2016093 哈爾濱工業(yè)大學(威海)�？茖W研究基金項目No.HIT(WH)201414~~
【分類號】：TG453.9

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