利用管状试样测试各向异性材料双向应力状态力学性能的新方法

发布时间：2018-03-13 07:00

本文选题：铝合金挤压管　切入点：各向异性　出处：《金属学报》2017年09期 　论文类型：期刊论文

【摘要】：为解决各向异性材料双向加载性能测试理论模型存在的测试物理量过多且实测困难的问题,提出了一种采用管状试样胀形直接测试双向加载力学性能的新方法:一点法。利用圆几何轮廓线为显性函数表达式的特征,推导了胀形过程中最高点轴向曲率半径和壁厚理论模型。仅需在胀形过程中测量最高点胀形高度,即可获得材料双向加载下的力学性能,为建立一个简单可靠且能在线实时测量的材料力学性能测试方法奠定了基础。并利用所建立的测试方法进行了AA6061铝合金挤压管坯的胀形实验。结果表明:管坯自由胀形时,其最高点实时壁厚和曲率半径均可表示为最高点胀形高度的显示函数。轮廓形状理论模型的预测精度随膨胀率的增大先提高后降低,膨胀率约为13%时预测精度最高,当膨胀率超过20%后,预测精度开始下降,但最大误差不超过±0.9%。最高点实时壁厚理论模型的预测精度基本不受试件几何尺寸的影响,长径比和径厚比改变时,差异很小,预测误差均不超过0.8%,这对保证双向加载条件下的力学性能测试精度是非常有益的。一点法可同时测得环向和轴向的应力应变分量,这为进一步分析各向异性对复杂应力状态下材料的流动及后继屈服奠定了基础。
[Abstract]:In order to solve the problem that the testing physical quantity is too much and the measurement is difficult in the theoretical model of anisotropic material under biaxial loading, In this paper, a new method for directly measuring the mechanical properties of tubular specimens under biaxial loading is proposed: the one-point method. Using the characteristic of the explicit function expression of circular geometric contours, a new method is proposed to measure the mechanical properties of tubular specimens directly under biaxial loading. The theoretical model of axial curvature radius and wall thickness of the highest point in bulging process is derived. The mechanical properties of the material under bidirectional loading can be obtained by measuring the height of the highest point bulging in the process of bulging. It lays a foundation for the establishment of a simple, reliable and on-line testing method for mechanical properties of materials. The bulging experiment of AA6061 aluminum alloy extruded tube billet is carried out by using the established test method. The results show that when the tube billet bulges freely, The real time wall thickness and curvature radius of the highest point can be expressed as the display functions of the height of the highest bulge. The prediction accuracy of the contour shape theoretical model increases first and then decreases with the increase of the expansion rate, and the prediction accuracy is the highest when the expansion rate is about 13. When the expansion ratio exceeds 20%, the prediction accuracy begins to decrease, but the maximum error is not more than 卤0.9.The prediction accuracy of the theoretical model of real-time wall thickness at the highest point is basically independent of the geometric dimension of the specimen, but the difference is very small when the ratio of length to diameter and the ratio of diameter to thickness vary. The prediction error is not more than 0.80.This is very helpful to ensure the accuracy of mechanical properties measurement under bidirectional loading. The one-point method can measure the stress and strain components in both circumferential and axial directions at the same time. This lays a foundation for further analysis of anisotropic flow and subsequent yield of materials under complex stress state.
【作者单位】：哈尔滨工业大学(威海)材料科学与工程学院;哈尔滨工业大学材料科学与工程学院;哈尔滨工业大学精密工程研究所;
【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】：TG115.5

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