We present a gradient-enhanced damage model for ductile fracture modeling, describing the degraded material response coupled to temperature. Continuum thermodynamics is used to represent components of the energy dissipation as induced by the effective material response, thermal effects, and damage evolution. The viscoplastic Johnson-Cook constitutive model serves as prototype for the effective material. The continuum damage evolution of Lemaitre type is focusing the degradation of the shear response, eventually leading to ductile shear failure. A novel feature is the damage-driving dissipation rate, allowing for elastic and plastic components separated by a global damage threshold for accumulation of inelastic damage-driving energy. In the application to a dynamic split-Hopkinson test and two quasi-static tensile tests, the gradient damage model is compared with the corresponding local model. For isothermal conditions, the examples show that both damage models exhibit mesh convergent behavior when using the global damage threshold.

中文翻译：

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韧性断裂的梯度增强损伤增长模型

我们提出了一种用于延性断裂建模的梯度增强损伤模型，描述了与温度耦合的退化材料响应。连续介质热力学用于表示由有效材料响应、热效应和损伤演变引起的能量耗散分量。粘塑性 Johnson-Cook 本构模型作为有效材料的原型。Lemaitre 型的连续损伤演化集中于剪切响应的退化，最终导致延性剪切破坏。一个新颖的特征是损伤驱动耗散率，允许弹性和塑料组件被一个全局损伤阈值分开，以积累非弹性损伤驱动能量。在动态分裂霍普金森试验和两个准静态拉伸试验的应用中，梯度损伤模型与相应的局部模型进行比较。对于等温条件，示例表明当使用全局损伤阈值时，两种损伤模型都表现出网格收敛行为。