Contribution to an efficient FE-based design of magnesium sheet parts

轻量化结构是汽车制造商为降低S汽车的重量、燃油消耗和整体温室气体排放而采取的已知战略。为了达到这些目标，铝合金以及更高和高强度钢的使用日益成为系列化生产的标准。尽管镁的密度很低，但仍难以被接受，这主要是因为人们对其不同寻常的塑性行为缺乏了解，而且在商业有限元程序中也缺乏足够的材料模型。本研究项目的任务是实施并进一步开发一种高效的镁板材料模型，以克服这一缺陷。为此，建立了Li等人的本构材料模型TWINLAW。(2010)将使用UMAT子例程在ABAQUS/Standard中实施。将用改进的各向异性屈服准则取代原模型的von Mose屈服准则，以解决材料的显著各向异性。仅有部分描述的模式的实施及其进一步发展是一项具有挑战性的任务。事实上，由于采用了先进的各向异性屈服准则，整个本构模型将受到影响，可能会经历一次重大的修改。由于新流面的复杂性，预计积分算法将会改变。李等人的补充。(2010)，该模型的调查仅在室温下进行，模型将在增强温度下进行等温测试。在相关成形工艺温度范围内的验证将使用已实施的以及新的实验方法来执行。

Light weight construction is for automotive manufactures a known strategy in order to reduce car´s weight, fuel consumption and overall greenhouse emissions. In order to meet these targets the use of aluminum alloy as well as higher- and high-strength steels has increasingly become a standard for series production. Magnesium has struggled for acceptance despite the low density, mainly due to the lack of knowledge of its unusual plastic behavior and the absence of adequate material models in commercial FE-programs. The mission of the present research project is to implement and further develop an efficient material model for magnesium sheets in order to overcome this deficit. For this purpose, the constitutive material model called TWINLAW from Li et al. (2010) will be implemented in ABAQUS/Standard using a UMAT subroutine. The von Mises yield criterion of the model in its original form will be substitute by an advanced anisotropic yield criterion to address the pronounced anisotropy of the material. The implementation of the only partially described model together with its further development represents a challenging task. In fact, the whole constitutive model will be impacted by the adoption of an advanced anisotropic yield criterion and will likely undergo a major rework. It is among other things expected that the integration algorithm will be changed because of the complexity of the new flow surface. Supplementary to Li et al. (2010) whose investigations were carried out at room temperature only, the model will be isothermally tested at enhanced temperatures. This validation in a relevant forming technology temperature range will be performed using already implemented as well as new experimental methods.