Material testing machine for superposition of tension/compression, torsion and internal pressure

金属结构材料的损伤和破坏行为在很大程度上取决于局部应力状态。损伤模型通过使用相应的材料参数来描述这种应力状态相关性，用于评估材料和部件的完整性以及模拟成形过程以达到损伤控制的目的。这些参数的校准以及模型的验证需要一种测试技术，借助于该技术可以以定义的方式设置试件中的应力状态。然而，申请者的设施目前还不能使用这种测试技术。相反，应力状态是通过调整单轴试验框架内的试件几何形状来产生的，因此既不能设置任意的应力状态，也不能可靠地避免不成比例的应变路径。这将由所申请的试验机进行补救，该试验机将法向应力和剪切应力叠加到由内部压力产生的静水压力上，从而能够系统地设置特定的应力状态。所申请的试验机是制造商目录中找不到的一种独特的试验机，因为除了拉伸/压缩和扭转试验外，它还提供对空心试件施加内压的功能。因此，机器必须根据本提案中所述申请人的意愿进行单独改装。在这一点上，测试机器在亚琛将是独一无二的。由于所有三名申请者都是金属设计中心的附属机构，该中心被选为机器的地点。这种位置的选择确保了所有申请者对机器的最佳使用。该试验机还将集成到由材料科学和工程部创建的虚拟StrucMatLab中。这将在后续工作和维护成本方面发挥协同效应，并进一步增加科学家，特别是地质资源和材料工程学院的科学家对机器的可及性。许多正在进行或刚刚申请的研究项目将受益于试验机器的采购，包括基础科学和更多以应用为导向的项目，包括材料科学和材料工程、生产工程(成形技术)和土木工程(钢结构)。

The damage and failure behavior of metallic structural materials is significantly dependent on the local stress state. Damage models, that are used to both evaluate material and component integrity as well as to simulate forming processes with the aim of damage control, describe this stress state dependency by using corresponding material parameters. The calibration of these parameters as well as the validation of the models require a test technique with the help of which the stress states in specimens can be set in a defined manner. However, such a test technique is currently not available at the applicants’ facilities. Instead, the stress state is generated by adjustment of the specimen geometry within the framework of uniaxial tests, whereby neither arbitrary stress states can be set, nor can non-proportional strain paths be reliably avoided. This is to be remedied by the testing machine applied for, which superimposes normal and shear stresses onto hydrostatic stresses generated by internal pressure thus enabling the systematic setting of specific stress states. The applied for testing machine is a unique machine that cannot be found in the manufacturers’ catalogs because, in addition to tensile/compression as well as torsion testing, it also provides for the application of internal pressure to hollow specimens. Therefore, the machine must be individually adapted to the wishes of the applicants as formulated in the present proposal. To this extent, the testing machine will be unique at the Aachen location.As all three applicants are affiliated in the Center for Metallic Design, the center was selected as the location for the machine. This choice of location ensures optimal use of the machine by all applicants. The testing machine is also to be integrated into the virtual StrucMatLab founded by the Division of Materials Science and Engineering. This will leverage synergy effects in terms of follow-up as well as maintenance costs and furthermore, increase the accessibility of the machine for scientists, especially from the Faculty of Georesources and Materials Engineering.Many research projects that are already underway or have just been applied for will benefit from the procurement of the testing machine, covering both basic science and more application-oriented projects from the fields of materials science and materials engineering, production engineering (forming technology) and civil engineering (steel construction).