Łagoda Tadeusz, Głowacka Karolina, Kurek Andrzej
Faculty of Mechanical Engineering, Opole University of Technology, 45-758 Opole, Poland.
Materials (Basel). 2020 Oct 29;13(21):4850. doi: 10.3390/ma13214850.
The main purpose of this paper is to propose, based on the literature review, a new multiaxial fatigue strain criterion, analogous to the Dang Van stress criterion, considering the maximum amplitude of the shear strain and volumetric strain. The proposed strain criterion was successfully verified by fatigue tests in cyclic bending with torsion of specimens made of 2017A-T4 and 6082-T6 aluminum alloy. The scatter of test results for cyclic bending and the combination of cyclic bending and torsion is included in the scatter of tests for the cyclic torsion of the analyzed materials. Fracture surfaces for respective bending and torsion in the 6082-T6 aluminum test with strain control showed that, in the case of bending, cracks can be observed that develop from the surface of the specimen towards the bending plane. They are inclined from the fatigue crack at an angle of 45° in relation to the crack surface and the remaining cracks come from the static fracture. In the case of torsion, however, a conical fracture at 45° and a static torsion zone can be observed.
本文的主要目的是在文献综述的基础上，提出一种新的多轴疲劳应变准则，类似于当凡应力准则，该准则考虑了剪切应变和体积应变的最大幅值。通过对2017A-T4和6082-T6铝合金制成的试样进行循环弯曲加扭转疲劳试验，成功验证了所提出的应变准则。循环弯曲试验结果以及循环弯曲与扭转组合试验结果的离散性包含在所分析材料的循环扭转试验离散性之中。在6082-T6铝合金应变控制试验中，各弯曲和扭转情况下的断口表明，在弯曲情况下，可以观察到裂纹从试样表面向弯曲平面扩展。它们相对于裂纹表面从疲劳裂纹处以45°角倾斜，其余裂纹来自静断。然而，在扭转情况下，可以观察到45°的锥形断口和静扭区。
