Cyclic plasticity modeling and finite element analyzes of a circumferentially notched round bar under combined axial and torsion loadings
Cyclic plasticity modeling and finite element analyzes of a circumferentially notched round bar under combined axial and torsion loadings
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DOI：
10.1016/j.matdes.2011.07.022
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发表时间：
2012-02
影响因子：
8.4
通讯作者：
Mehmet Firat-
中科院分区：
文献类型：
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作者：
Mehmet Firat-
提出了一种适用于金属结构疲劳损伤建模的循环塑性模型，并描述了该模型在小应变塑性框架下的有限元实现。该模型采用应力空间中的von Mises屈服曲面，其评价遵循Armstrong-Frederick型非线性运动硬化规则，并假设正态性假设与关联流动规则相结合。采用增量隐式迭代算法对得到的应力-应变方程进行数值求解，采用塑性模型得到的连续切线进行有限元计算。将所建立的有限元计算模型应用于周向缺口试件轴扭联合加载试验的循环变形分析。计算的缺口根变形与测量的缺口根应变历史进行了比较。对模型预测的评估表明，非比例加载试验的模拟精度很高。计算得到的应变曲线与试验数据基本一致，且与实测剪切-轴向应变曲线定性匹配。在比例平衡扭转-轴向加载下，非线性剪切应变-轴向应变循环也得到了较好的模拟。缺口根应变的误差与加载路径形状有关，与轴向应变相比，剪切应变误差相对较大。计算机解决时间也是可以接受的。
A cyclic plasticity model suitable for fatigue damage modeling of metallic structures is presented and its finite element (FE) implementation is described within the small strain plasticity framework. The model uses the von Mises yield surface in stress space whose evaluation follows an Armstrong–Frederick type of nonlinear kinematic hardening rule, and the normality hypothesis in conjunction with the associative flow rule is assumed. An incremental implicit-iterative algorithm was employed for the numerical solution of resulting stress–strain equations, and the continuum tangent obtained from plasticity model was used in FE implementation. The developed FE computational model is applied in the cyclic deformation analysis of a circumferentially notched specimen in combined axial force-torsion loading tests. The computed notch root deformations were compared with measured notch root strain histories. An assessment of model predictions showed that non-proportional loading tests have been simulated with a good accuracy. The computed strain loops were in accord with experimental data and matched qualitatively with measured shear – axial strain histories irrespective of loading path of the test. In proportional balanced torsion-axial loading, the nonlinear shear strain – axial strain loops were also simulated properly. The errors in notch root strains were dependent on the loading path shape, and compared to axial strains, the shear strain errors were relatively greater. The computer solution times were also acceptable.