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基于非关联流动规律的Gotoh屈服准则的参数确定方法

PARAMETER DETERMINATION METHOD OF GOTOH YIELD CRITERION BASED ON NON-ASSOCIATED FLOW RULE

  • 摘要: 屈服准则对板料成形过程的理论解析、工艺优化和有限元模拟有着重要的影响. 通过提高屈服准则的各向异性表征能力, 可以确保成形过程的可靠性及实际预测的准确性. 本文基于非关联流动法则, 给出了Gotoh屈服准则一套全新的参数求解方法. 在结合常用屈服准则并考虑流动规律的基础上, 分别以5754O铝合金、DP980先进高强钢和SAPH440结构钢作为研究对象, 进行了不同加载路径下各向异性变形行为的预测. 根据Gotoh屈服准则推导的屈服函数、塑性势函数以及基于关联流动的理论函数计算出屈服应力和各向异性指数r值随加载角度的分布趋势, 进而针对平面应力状态的屈服轨迹展开分析, 验证了不同屈服准则和流动规律对各向异性屈服行为的预测精度. 理论与实验数据对比结果表明: 不同屈服准则针对同种板料在流动规律一致的情形下其表征各向异性的能力有显著差异; 相同屈服准则基于不同流动规律其表征能力也具有明显差别. 基于非关联流动的屈服准则能极大地提高精度, 各向异性表征能力显著加强. 相关结果能够为各向异性屈服准则在塑性成形领域的实际应用方案提供重要参考.

     

    Abstract: Yield criterion has an important influence on theoretical analysis, process optimization and finite element simulation of sheet metal forming process. By enhancing the anisotropy characterization ability of the yield criterion, the reliability of the forming process and the accuracy of the actual prediction can be ensured. In this paper, a new set of parameter solving method for the Gotoh yield criterion is given based on non-associated flow rule. On the basis of common yield criteria and different flow rules, the 5754O aluminum alloy, DP980 advanced high-strength steel and SAPH440 structural steel sheet were taken as examples, the anisotropic deformation behavior of which were predicted under different loading paths. The yield function and plastic potential function derived from Gotoh yield criterion and the theoretical functions based on associated flow rule were used to calculate the distributions trend of yield stress and r-value along different loading angle. Furthermore, the yield locus under the plane stress state is analyzed, and the prediction accuracy the anisotropic yield behavior based on different yield criteria and the flow rules is verified. By comparing the theoretical and experimental results, it is shown that different yield criteria with same flow rule have significant differences in anisotropic characterization ability for the same sheet. There are also obvious deviations in the characterization process when the yield criterion is adopted based on different flow rules. The yield criterion based on non-associated flow rule can greatly improve its own flexibility and accuracy, and the characterization ability is significantly enhanced. The final results will provide an important reference for the actual application strategy of the yield criteria in the plastic forming field.

     

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