Abstract Phenomenological ductile fracture criteria have defining parameters to be determined from experimental fracture tests. For a precise calibration of a ductile fracture criterion, fracture experiments should cover a wide range of stress states. To this end, sheet metal specimens with different geometries are tested using various experimental setups, such as uniaxial tension, Nakazima, and butterfly tests. Usually, a combination of these tests is performed to capture a wide range of stress states, which makes the calibration procedure more difficult and tedious. In contrast, in the present research, only the hydraulic bulge test with a circular die is utilized to calibrate a ductile fracture criterion with three defining constants. To cover a wide range of stress triaxiality from the pure shear to the equibiaxial tension, circular blanks with different geometries are designed and developed with the aid of the finite element (FE) simulation. Among the presented geometries, there is an innovative specimen for reproducing the in-plane shear state using the hydraulic bulge test. In the present research, the ductile fracture of the AA6061-T6 aluminum alloy sheet is investigated. By comparing results of the FE modeling and the experiment of the hydraulic bulging, it is shown that the pressure, the bulging height, and the sheet thickness at the instant of fracture onset can be predicted with a reasonable accuracy by the ductile fracture model calibrated using the proposed test. Therefore, the designed specimens allow the hydraulic bulge test to be implemented for investigating the ductile fracture of sheet metals under a wide range of stress conditions.

中文翻译：

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使用液压胀形试验校准从剪切到等双轴拉伸的韧性断裂准则

摘要 现象学韧性断裂标准具有定义参数，可通过实验断裂试验确定。为了精确校准延展性断裂准则，断裂实验应涵盖广泛的应力状态。为此，使用各种实验设置对具有不同几何形状的钣金试样进行测试，例如单轴拉伸、Nakazima 和蝴蝶测试。通常，执行这些测试的组合以捕获广泛的应力状态，这使得校准过程更加困难和乏味。相比之下，在目前的研究中，仅使用圆形模具的液压膨胀试验来校准具有三个定义常数的韧性断裂标准。为了涵盖从纯剪切到等双轴拉伸的广泛应力三轴性，借助有限元 (FE) 模拟设计和开发具有不同几何形状的圆形毛坯。在呈现的几何形状中，有一个创新的试样，用于使用液压膨胀试验再现平面内剪切状态。本研究对AA6061-T6铝合金薄板的韧性断裂进行了研究。将有限元建模结果与水力胀形实验结果进行比较，结果表明，通过使用以下方法校准的韧性断裂模型，可以合理准确地预测断裂开始时刻的压力、胀形高度和板材厚度。建议的测试。因此，设计的试样允许实施液压膨胀试验，以研究在各种应力​​条件下金属板的延性断裂。