基于二次多项式新本构模型的铝合金搅拌摩擦焊板材成形极限研究
发布时间：2018-07-22 17:37
【摘要】：针对铝合金焊缝性能低于母材、现有成形极限分析方法不适宜分析铝合金搅拌摩擦焊板材成形极限的现状,提出了一种基于二次多项式新本构模型的铝合金拼焊板成形极限理论模型。核心思想为利用材料自身的性能差异替代经典M-K理论模型的沟槽假设。针对铝合金硬化指数低、幂指数回归精度差的问题,将二次多项式新本构模型应用于M-K理论模型,最终建立了适合于铝合金搅拌摩擦焊拼焊板的成形极限理论预测模型。对铝合金搅拌摩擦焊板材进行了成形极限实验,并通过XJTUDIC三维数字散斑应变变形测量系统实时测量变形过程中的应变值,得到了铝合金搅拌摩擦焊拼焊板的实验成形极限图。最后对实验结果和理论分析结果进行了对比。相比传统的幂指数本构模型,二次多项式对应力-应变曲线的回归,无论在初试屈服阶段或后期变形阶段均有很好的吻合精度。幂指数最大拟合误差超过12%,而二次多项式的拟合误差小于1%,二次多项式回归模型能很好地拟合铝合金搅拌摩擦焊接接头的应力-应变关系;采用二次多项式本构关系的理论模型能很好地预测铝合金搅拌摩擦焊板材的成形极限,第一主应变的预测误差小于0.01;而幂指数理论模型则导致平面应变状态下的极限应变预测结果明显不准,在相同应变路径下第一主应变的预测误差达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.
【作者单位】： 哈尔滨工业大学(威海);威海北洋电气集团股份有限公司;
【基金】：国家自然科学基金项目Nos.51405102和51475121 中国博士后科学基金项目No.2015M570286 中央高校基本科研业务费专项资金项目No.HIT.NSRIF.2016093 哈尔滨工业大学(威海)校科学研究基金项目No.HIT(WH)201414~~
【分类号】：TG453.9
[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.
【作者单位】： 哈尔滨工业大学(威海);威海北洋电气集团股份有限公司;
【基金】：国家自然科学基金项目Nos.51405102和51475121 中国博士后科学基金项目No.2015M570286 中央高校基本科研业务费专项资金项目No.HIT.NSRIF.2016093 哈尔滨工业大学(威海)校科学研究基金项目No.HIT(WH)201414~~
【分类号】：TG453.9
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