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Size effect on the shear damage under low stress triaxiality in micro-scaled plastic deformation of metallic materials
Materials & Design ( IF 8.4 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.matdes.2020.109107
Jilai Wang , Chuanzheng Li , Yi Wan , Chengpeng Zhang , Jiaqi Ran , M.W. Fu

Abstract Micro-forming is one of the major micro-manufacturing methods with promising application potentials, in which the damage response and fracture behavior need to be insightfully addressed. Among all the damage criteria to predict fracture, GTN model is a widely-used one and able to predict void-dominated fracture in micro-scale deformation. However, it is not very applicable under low stress triaxiality and shear-dominated condition. An in-depth understanding of shear damage and its potential size effect are crucial to explore the micro-scaled damage and fracture mechanisms. This research characterizes the size effect on flow stress via employing a combined constitutive model, and an approach for applying a phenomenological shear damage evolution law to the GTN-Thomason model via considering the size effect is developed. The prediction of micro-scaled fracture in a wide stress triaxiality range is thus enabled. Through simulation and experiment, the proposed model is validated and verified. In addition, stress state parameters including stress triaxiality, Lode parameter, and weight function, are also discussed, and the two damage parameters are analyzed quantificationally to reveal different fracture mechanisms occurring in different stress states and grain sizes. The research thus facilitates the physical insight and in-depth understanding of the size effect on damage evolution and fracture formation in micro-scaled plastic deformation of materials.

中文翻译:

金属材料微尺度塑性变形低应力三轴下剪切损伤的尺寸效应

摘要 微成形是具有广阔应用潜力的主要微制造方法之一,其中损伤响应和断裂行为需要深入研究。在预测断裂的所有损伤准则中,GTN 模型是一种广泛使用的模型,能够预测微尺度变形中以空隙为主的断裂。但是,它在低应力三轴性和剪切主导的条件下不太适用。深入了解剪切损伤及其潜在的尺寸效应对于探索微观损伤和断裂机制至关重要。本研究通过采用组合本构模型来表征尺寸对流动应力的影响,并开发了一种通过考虑尺寸效应将现象学剪切损伤演化规律应用于 GTN-Thomason 模型的方法。因此,可以预测宽应力三轴度范围内的微尺度断裂。通过仿真和实验,对所提出的模型进行了验证和验证。此外,还讨论了应力状态参数,包括应力三轴性、洛德参数和权重函数,并对这两个损伤参数进行了量化分析,揭示了不同应力状态和晶粒尺寸下发生的不同断裂机制。因此,该研究促进了对材料微尺度塑性变形中损伤演化和断裂形成的尺寸效应的物理洞察和深入理解。还讨论了应力状态参数,包括应力三轴性、Lode 参数和权重函数,并对这两个损伤参数进行了量化分析,揭示了在不同应力状态和晶粒尺寸下发生的不同断裂机制。因此,该研究促进了对材料微尺度塑性变形中损伤演化和断裂形成的尺寸效应的物理洞察和深入理解。还讨论了应力状态参数,包括应力三轴性、Lode 参数和权重函数,并对这两个损伤参数进行了量化分析,揭示了在不同应力状态和晶粒尺寸下发生的不同断裂机制。因此,该研究促进了对材料微尺度塑性变形中损伤演化和断裂形成的尺寸效应的物理洞察和深入理解。
更新日期:2020-11-01
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