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Ductile fracture under proportional and non-proportional multiaxial loading
International Journal of Solids and Structures ( IF 3.6 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.ijsolstr.2020.11.011 Madhav Baral , Yannis P. Korkolis
International Journal of Solids and Structures ( IF 3.6 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.ijsolstr.2020.11.011 Madhav Baral , Yannis P. Korkolis
Abstract This paper revisits proportional and non-proportional experiments performed earlier by the authors, with the aim to establish the fracture envelope of the material. The experiments involved inflation of thin-walled AA6260-T4 tubes under axial force and internal pressure. By controlling the force/pressure ratio during the experiments, proportional (i.e., radial) and non-proportional (i.e., corner) loading paths were generated. These experiments are reviewed here. Since fracture is of interest, a computationally-efficient finite element model with solid element discretization around the anticipated fracture location and shell elements in the rest of the tube is described. The Yld2000-2D and Yld2004-3D yield criteria are calibrated and implemented in the simulations. In concert with earlier findings, these criteria are found to offer significantly better agreement with the experiments than von Mises. In particular, the local normals to the yield locus show discrepancies under 3°, while 8°–12° are typical for von Mises. This has significant impact in the prediction of the induced strain paths. The fidelity of the modeling framework is established by comparing the predictions of average stress-strain responses, as well as post-mortem local surface strains, to experiments. Then, the finite element models are used to establish the fracture locus of the material, under proportional loading. The fracture strains are found to increase monotonically as the triaxiality approaches zero from above, i.e., no spike is found at triaxiality of 1/3. The fracture strains also increase at higher triaxialities. The presence of the radial stress shifts that spike from triaxiality of 2/3 (equibiaxial tension) to lower values. By superposing the non-proportional results, it is found that the fracture locus is path-dependent.
中文翻译:
比例和非比例多轴加载下的韧性断裂
摘要 本文回顾了作者之前进行的比例和非比例实验,旨在建立材料的断裂包络线。实验涉及在轴向力和内部压力下对薄壁 AA6260-T4 管进行充气。通过在实验过程中控制力/压力比,生成了成比例(即径向)和非成比例(即拐角)加载路径。这些实验在这里进行了回顾。由于裂缝是有趣的,因此描述了一个具有计算效率的有限元模型,该模型具有围绕预期裂缝位置和管其余部分中的壳单元进行离散化的实体单元。Yld2000-2D 和 Yld2004-3D 良率标准在模拟中得到校准和实施。与之前的研究结果一致,发现这些标准与实验的一致性明显优于 von Mises。特别是,屈服轨迹的局部法线显示出 3° 以下的差异,而 von Mises 的典型差异是 8°–12°。这对诱导应变路径的预测具有重要影响。建模框架的保真度是通过将平均应力应变响应的预测以及验尸局部表面应变与实验进行比较来建立的。然后,使用有限元模型建立材料在比例载荷下的断裂轨迹。当三轴度从上方接近零时,发现断裂应变单调增加,即在 1/3 三轴度处没有发现尖峰。在更高的三轴度下,断裂应变也会增加。径向应力的存在将峰值从 2/3(等双轴张力)的三轴性转变为较低的值。通过叠加非比例结果,发现断裂轨迹是路径依赖的。
更新日期:2021-02-01
中文翻译:
比例和非比例多轴加载下的韧性断裂
摘要 本文回顾了作者之前进行的比例和非比例实验,旨在建立材料的断裂包络线。实验涉及在轴向力和内部压力下对薄壁 AA6260-T4 管进行充气。通过在实验过程中控制力/压力比,生成了成比例(即径向)和非成比例(即拐角)加载路径。这些实验在这里进行了回顾。由于裂缝是有趣的,因此描述了一个具有计算效率的有限元模型,该模型具有围绕预期裂缝位置和管其余部分中的壳单元进行离散化的实体单元。Yld2000-2D 和 Yld2004-3D 良率标准在模拟中得到校准和实施。与之前的研究结果一致,发现这些标准与实验的一致性明显优于 von Mises。特别是,屈服轨迹的局部法线显示出 3° 以下的差异,而 von Mises 的典型差异是 8°–12°。这对诱导应变路径的预测具有重要影响。建模框架的保真度是通过将平均应力应变响应的预测以及验尸局部表面应变与实验进行比较来建立的。然后,使用有限元模型建立材料在比例载荷下的断裂轨迹。当三轴度从上方接近零时,发现断裂应变单调增加,即在 1/3 三轴度处没有发现尖峰。在更高的三轴度下,断裂应变也会增加。径向应力的存在将峰值从 2/3(等双轴张力)的三轴性转变为较低的值。通过叠加非比例结果,发现断裂轨迹是路径依赖的。