A novel phase-field model for ductile fracture is presented. The model is developed within a consistent variational framework in the context of finite-deformation kinematics. A novel coalescence dissipation introduces a new coupling mechanism between plasticity and fracture by degrading the fracture toughness as the equivalent plastic strain increases. The proposed model is compared with a recent alternative where plasticity and fracture are strongly coupled. Several representative numerical examples motivate specific modeling choices. In particular, a linear crack geometric function provides an “unperturbed” ductile response prior to crack initiation, and Lorentz-type degradation functions ensure that the critical fracture strength remains independent of the phase-field regularization length. In addition, the response of the model is demonstrated to converge with a vanishing phase-field regularization length. The model is then applied to calibrate and simulate a three-point bending experiment of an aluminum alloy specimen with a complex geometry. The effect of the proposed coalescence dissipation coupling on simulations of the experiment is first investigated in a two-dimensional plane strain setting. The calibrated model is then applied to a three-dimensional calculation, where the calculated load-deflection curves and the crack trajectory show excellent agreement with experimental observations. Finally, the model is applied to simulate crack nucleation and growth in a specimen from a recent Sandia Fracture Challenge.

提出了一种新的韧性断裂相场模型。该模型是在有限变形运动学背景下的一致变分框架内开发的。一种新的聚结耗散通过随着等效塑性应变的增加而降低断裂韧性，从而在塑性和断裂之间引入了一种新的耦合机制。所提出的模型与最近的替代方案进行了比较，其中塑性和断裂强耦合。几个有代表性的数值例子激发了特定的建模选择。特别是，线性裂纹几何函数在裂纹萌生之前提供“不受干扰”的延性响应，洛伦兹型退化函数确保临界断裂强度保持与相场正则化长度无关。此外，模型的响应被证明收敛于消失的相场正则化长度。然后将该模型应用于校准和模拟具有复杂几何形状的铝合金试样的三点弯曲实验。首先在二维平面应变设置中研究了所提出的聚结耗散耦合对实验模拟的影响。然后将校准后的模型应用于三维计算，计算出的载荷-挠度曲线和裂纹轨迹与实验观察结果非常吻合。最后，该模型用于模拟来自最近的 Sandia 断裂挑战赛的试样中的裂纹成核和生长。然后将该模型应用于校准和模拟具有复杂几何形状的铝合金试样的三点弯曲实验。首先在二维平面应变设置中研究了所提出的聚结耗散耦合对实验模拟的影响。然后将校准后的模型应用于三维计算，计算出的载荷-挠度曲线和裂纹轨迹与实验观察结果非常吻合。最后，该模型用于模拟来自最近的 Sandia 断裂挑战赛的试样中的裂纹成核和生长。然后将该模型应用于校准和模拟具有复杂几何形状的铝合金试样的三点弯曲实验。首先在二维平面应变设置中研究了所提出的聚结耗散耦合对实验模拟的影响。然后将校准后的模型应用于三维计算，计算出的载荷-挠度曲线和裂纹轨迹与实验观察结果非常吻合。最后，该模型用于模拟来自最近的 Sandia 断裂挑战赛的试样中的裂纹成核和生长。然后将校准后的模型应用于三维计算，计算出的载荷-挠度曲线和裂纹轨迹与实验观察结果非常吻合。最后，该模型用于模拟来自最近的 Sandia 断裂挑战赛的试样中的裂纹成核和生长。然后将校准后的模型应用于三维计算，计算出的载荷-挠度曲线和裂纹轨迹与实验观察结果非常吻合。最后，该模型用于模拟来自最近的 Sandia 断裂挑战赛的试样中的裂纹成核和生长。