Abstract To solve the problem that the original GTN model cannot accurately simulate ductile fracture of material under low stress triaxiality, many scholars have made shear improvement to it, but these shear modified GTN models have their own advantages and disadvantages and the parameters are difficult to be determined. An improved shear modified GTN (ISMGTN) model containing two independent damage mechanisms is proposed for ductile fracture prediction of materials under different stress states. The shear damage parameters, tensile damage parameters and the hardening parameters are identified using a FE inverse identification method incorporating the Latin hypercube design, Kriging approximate model and NLPQL optimization method performed in the optimization software ISIGHT. Influence of each damage parameter on damage evolution under different stress states is analyzed by a unit cell model. Accuracy of the ISMGTN model and feasibility of the damage parameters identification method are verified by performing them on a material aluminum alloy 6061 with 0°, 30° and 60° shear tests, plate tensile tests, and notched tensile tests. Additionally, fracture morphology analyses of the fractured specimen and contour plots of the effective tensile damage and effective shear damage from the FE analysis using the identified parameters are performed to study possible mechanism of deformation and failure in microscale and macroscale perspectives, respectively, and a good consistence is obtained.

中文翻译：

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铝合金不同应力状态下塑性断裂的改进剪切修正GTN模型及其参数辨识

摘要 为解决原GTN模型不能准确模拟低应力三轴下材料的韧性断裂问题，许多学者对其进行了剪切改进，但这些剪切修正的GTN模型各有优缺点，参数难以确定。决定。提出了一种改进的剪切修正 GTN (ISMGTN) 模型，该模型包含两种独立的损伤机制，用于不同应力状态下材料的韧性断裂预测。剪切损伤参数、拉伸损伤参数和硬化参数使用有限元逆识别方法进行识别，该方法结合了拉丁超立方设计、克里金近似模型和在优化软件 ISIGHT 中执行的 NLPQL 优化方法。采用晶胞模型分析了不同应力状态下各损伤参数对损伤演化的影响。通过对材料铝合金6061进行0°、30°和60°剪切试验、板拉伸试验和缺口拉伸试验，验证了ISMGTN模型的准确性和损伤参数识别方法的可行性。此外，使用确定的参数对断裂试样进行断裂形貌分析，并从有限元分析中得到有效拉伸损伤和有效剪切损伤的等高线图，分别从微观和宏观角度研究变形和破坏的可能机制，并获得良好的结果。获得一致性。通过对材料铝合金6061进行0°、30°和60°剪切试验、板拉伸试验和缺口拉伸试验，验证了ISMGTN模型的准确性和损伤参数识别方法的可行性。此外，使用确定的参数对断裂试样进行断裂形貌分析，并从有限元分析中得到有效拉伸损伤和有效剪切损伤的等高线图，分别从微观和宏观角度研究变形和破坏的可能机制，并获得良好的结果。获得一致性。通过对材料铝合金6061进行0°、30°和60°剪切试验、板拉伸试验和缺口拉伸试验，验证了ISMGTN模型的准确性和损伤参数识别方法的可行性。此外，使用确定的参数对断裂试样进行断裂形貌分析，并从有限元分析中得到有效拉伸损伤和有效剪切损伤的等高线图，分别从微观和宏观角度研究变形和破坏的可能机制，并获得良好的结果。获得一致性。