A cyclic twin bridge shear test for the identification of kinematic hardening parameters
A cyclic twin bridge shear test for the identification of kinematic hardening parameters
复制标题
DOI：
10.1016/j.ijmecsci.2012.02.008
复制
发表时间：
2012-06
影响因子：
7.3
通讯作者：
Qing Yin;C. Soyarslan;A. Güner;A. Brosius;A. Tekkaya
中科院分区：
文献类型：
--
作者：
Qing Yin;C. Soyarslan;A. Güner;A. Brosius;A. Tekkaya
为了识别金属板材的运动硬化参数，提出了一种面内扭转双桥循环剪切试验方法。除了其简单性外，该测试值得注意的优点是：(A)与单侧剪切测试相比，减少了实验装置上的载荷；(B)两个剪切桥上的主应力相对于滚动方向的方向相同，例如，经典宫内剪切测试无法实现这一点；以及(C)不会因失稳机制(如屈曲或颈缩)而过早终止。两个主要的缺点似乎是：(A)由于剪力桥周围塑性区域的扩散系数，阻碍了在参数识别中使用解析解的初值问题；(B)模糊了与剪力桥的宽度成比例的各向异性材料响应。作为前者的补救措施，采用逆参数识别方法，通过设计测量的力矩和转角的目标函数来确定硬化参数。对于后者，选择了一个最优的剪力桥宽度，在不可能达到剪切平衡的情况下，该宽度也将使边缘效应最小化。材料模型采用基于Voce和Armstrong-Frederick的非线性各向同性和运动强化相结合的模型，并以ABAQUS/EXPLICIT的VUMAT子程序实现。采用三种不同的钢板材料，即低碳钢DC06、双相钢DP600和相变诱发塑性钢TRIP700进行应变控制试验。这些只有一个周期的试验，包括正向剪切和反向剪切阶段，只关注包辛格效应。安定值、棘轮、平均应力松弛、循环硬化和软化等现象在不同应力和应变加载循环下的变化不在本研究的范围之内。结果表明，该试验除了适用于运动硬化参数识别的目的外，还表明Armstrong-Frederick模型不能很好地捕捉所选材料的循环响应，特别是先进的高强度钢DP600和TRIP700。
A twin bridge cyclic shear test with in-plane torsion is proposed for the identification of kinematic hardening parameters for metallic sheets. Besides its simplicity, noteworthy advantages of the test are (a) reduced loads on the experimental device as compared to a one-sided shear test, (b) identical orientation of the principal stresses with respect to the rolling direction in both of the shear bridges, e.g. which cannot be realized by the classical Miyauchi shear test, and (c) no premature termination by instability mechanisms such as buckling or necking. Two main disadvantages appear to be (a) a preclusion of the use of analytically solved initial value problem in parameter identification due to a diffusivity of the plastic region around the shear bridges, (b) smeared out anisotropic material response proportional with the width of the shear bridge. As a remedy for the former, an inverse parameter identification methodology is used to determine the hardening parameters using an objective function devising the measured moment and rotation angle. For the latter, an optimum shear bridge width is selected which also minimizes the edge effect where a shear equilibrium is not possible. A combined non-linear isotropic and kinematic hardening model respectively based on Voce and Armstrong–Frederick is selected as the material model which is implemented as a VUMAT subroutine for ABAQUS/EXPLICIT. Strain-controlled tests are conducted using three different classes of steel sheet materials, namely a mild steel DC06, a dual phase steel DP600 and a Transformation Induced Plasticity steel TRIP700. These tests with one cycle including a forward shearing and a reverse shearing phase merely focus on the Bauschinger effect. Variations with different stress and strain based loading cycles for phenomena like shakedown, ratcheting, mean stress relaxation, cyclic hardening and softening are not explored and left beyond the scope of the current study. The results, besides showing the applicability of the test to the kinematic hardening parameter identification purposes, also show that the Armstrong–Frederick model falls short to capture the cyclic response of the selected materials, especially advanced high strength steels DP600 and TRIP700.