A series of cyclic loading tests of G20Mn5QT cast steel are carried out at the strain ratio of − 1. The results of tests show that the G20Mn5QT cast steel has the similar tendency in cyclic softening with different constant strain amplitude. A slight strain softening is observed, and then the stress states keep steady during the remaining cycles. A new damage variable is proposed considering the effects of strength degeneration within two inner variables which are the maximum equivalent plastic strain and the equivalent plastic strain increment. The damage variable provides better insight into the multiaxial cyclic loading and gives a reasonable prediction of failure under the loading history of constant strain amplitude. The proposed damage variable is further introduced in the cyclic constitutive model by the user subroutine interfaces VUMAT by the software ABAQUS. The relationships between the equivalent plastic strain and the damage variable, Young’s modulus and yield strength are finally put forward as it is expedient to get the equivalent plastic strain in the numerical analysis.

中文翻译：

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G20Mn5QT铸钢的循环响应与本构模型研究。

G20Mn5QT铸钢在-1的应变比下进行了一系列循环载荷试验。试验结果表明，G20Mn5QT铸钢在不同的恒定应变幅值下具有相似的循环软化趋势。观察到轻微的应变软化，然后应力状态在其余循环中保持稳定。考虑到强度退化的两个内部变量，即最大等效塑性应变和等效塑性应变增量，提出了一个新的损伤变量。损伤变量可以更好地了解多轴循环载荷，并给出在恒定应变幅度的载荷历史下失效的合理预测。通过用户子例程接口VUMAT和ABAQUS软件，将提出的损伤变量进一步引入循环本构模型。最后提出了当量塑性应变与损伤变量，杨氏模量和屈服强度之间的关系，因为在数值分析中可以方便地得到当量塑性应变。