【摘要】：針對(duì)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(xiàng)式新本構(gòu)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(shè)。針對(duì)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(xiàng)式新本構(gòu)模型應(yīng)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(yù)測(cè)模型。對(duì)鋁合金攪拌摩擦焊板材進(jìn)行了成形極限實(shí)驗(yàn),并通過XJTUDIC三維數(shù)字散斑應(yīng)變變形測(cè)量系統(tǒng)實(shí)時(shí)測(cè)量變形過程中的應(yīng)變值,得到了鋁合金攪拌摩擦焊拼焊板的實(shí)驗(yàn)成形極限圖。最后對(duì)實(shí)驗(yàn)結(jié)果和理論分析結(jié)果進(jìn)行了對(duì)比。相比傳統(tǒng)的冪指數(shù)本構(gòu)模型,二次多項(xiàng)式對(duì)應(yīng)力-應(yīng)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(xiàng)式的擬合誤差小于1%,二次多項(xiàng)式回歸模型能很好地?cái)M合鋁合金攪拌摩擦焊接接頭的應(yīng)力-應(yīng)變關(guān)系;采用二次多項(xiàng)式本構(gòu)關(guān)系的理論模型能很好地預(yù)測(cè)鋁合金攪拌摩擦焊板材的成形極限,第一主應(yīng)變的預(yù)測(cè)誤差小于0.01;而冪指數(shù)理論模型則導(dǎo)致平面應(yīng)變狀態(tài)下的極限應(yīng)變預(yù)測(cè)結(jié)果明顯不準(zhǔn),在相同應(yīng)變路徑下第一主應(yīng)變的預(yù)測(cè)誤差達(dá)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(xué)(威海);威海北洋電氣集團(tuán)股份有限公司;
【基金】：國家自然科學(xué)基金項(xiàng)目Nos.51405102和51475121 中國博士后科學(xué)基金項(xiàng)目No.2015M570286 中央高校基本科研業(yè)務(wù)費(fèi)專項(xiàng)資金項(xiàng)目No.HIT.NSRIF.2016093 哈爾濱工業(yè)大學(xué)(威海)�？茖W(xué)研究基金項(xiàng)目No.HIT(WH)201414~~
【分類號(hào)】：TG453.9

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