The predictability of strain distributions and the related prediction of hardening and failure plays a central role in tool and process design for any metal forming process. Studying yielding behaviour, it was discovered that for various well established yield loci no satisfying agreement between DIC (digital image correlation) measurement of strain distribution and simulation result could be obtained, even after optimization of parameters based on associated flow assumption. In parallel, crystal plasticity simulations were investigated with the objective to predict the relation between stress and strain ratios for a large number of load cases based on texture measurement. To include macroscopic data, a secondary strategy uses cruciform tension specimen as defined in ISO16842 to obtain strain and stress ratios. The resulting relations were then applied separately as input parameters for the plastic yield description. Both approaches reach high agreement between forming experiment and simulation. Against the previous assumption, the output can be obtained with either anisotropic or free shape yield loci and associated flow description. The methodology discussed provides an alternative and challenges to rethink the definition of yielding for aluminium alloys on the example of an AA6014-T4 aluminium alloy.

应变分布的可预测性以及硬化和破坏的相关预测在任何金属成型工艺的工具和工艺设计中都起着核心作用。在研究屈服行为时，发现即使对于基于相关流动假设的参数进行了优化，对于各种公认的屈服点，在应变分布的DIC（数字图像相关性）测量和模拟结果之间也无法获得令人满意的一致性。同时，研究了晶体可塑性模拟，目的是基于织构测量来预测大量工况下应力与应变比之间的关系。为了包括宏观数据，第二种策略是使用ISO16842中定义的十字形拉伸试样来获得应变和应力比。然后将所得关系作为塑料屈服说明的输入参数分别应用。两种方法在成形实验和仿真之间都达到了高度一致。与先前的假设相反，可以使用各向异性或自由形状屈服轨迹和关联的流量描述获得输出。所讨论的方法论为以AA6014-T4铝合金为例重新思考铝合金的屈服定义提供了一种选择和挑战。