Abstract This paper formulated and implemented a novel local continuum damage model to be used with a continuous or a continuous-discontinuous strategy to simulate crack growth in quasi-brittle failure for mode I and mixed-mode conditions. The damage model is based on an evolution law using only physical parameters, which can be obtained through fracture and resistance tests without the need for further calibration. The local energy dissipation is controlled through regularization by the fracture energy and element length ensuring that different mesh densities dissipated the same energy during the damage evolution. The proposed damage model is employed in a finite element framework in two strategies: (i) a continuous strategy in which only the continuum damage model is used to predict crack propagation failure; and (ii) a continuous-discontinuous strategy in which a discontinuous enrichment is used to insert a crack within the elements after the total damage state is reached with no ad-hoc threshold value for the transition from continuous to the discontinuous approach. Comprehensive validation is demonstrated through comparisons with experimental results for various types of tests in mode I and mixed-mode conditions: single edge notch beam, unnotched four-point beam, anti-symmetric four-point shear beam, and double-edge-notched specimen. The results demonstrated that the proposed damage model and both strategies successfully simulate the crack propagation and failure of all simulated tests. Good agreement with the experimental results is observed for the crack path, maximum load, and entire load-displacement softening curves with coarser meshes than other models of the literature. Furthermore, the 3D results of the mixed-mode double-edge-notched specimen show that the proposed model provides good results even with coarser meshes using 16 times fewer elements than recent and similar results from the literature.

中文翻译：

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使用连续或连续-不连续策略模拟模式 I 和混合模式条件下的准脆性破坏的新型连续损伤模型

摘要 本文制定并实现了一种新的局部连续损伤模型，该模型与连续或连续-不连续策略一起使用，以模拟 I 型和混合模式条件下准脆性破坏中的裂纹扩展。损伤模型基于仅使用物理参数的演化规律，可通过断裂和阻力测试获得，无需进一步校准。局部能量耗散通过断裂能和单元长度的正则化来控制，确保不同的网格密度在损伤演化过程中耗散相同的能量。提出的损伤模型在有限元框架中采用两种策略：(i) 连续策略，其中仅使用连续损伤模型来预测裂纹扩展失效；(ii) 连续-不连续策略，在达到总损伤状态后，使用不连续富集在单元内插入裂纹，从连续到不连续方法的过渡没有临时阈值。通过与模式 I 和混合模式条件下各种类型测试的实验结果进行比较，证明了全面验证：单边缺口梁、无缺口四点梁、反对称四点剪切梁和双边缺口试样. 结果表明，所提出的损伤模型和两种策略都成功地模拟了所有模拟试验的裂纹扩展和失效。对于裂纹路径、最大载荷、以及具有比文献中的其他模型更粗的网格的整个载荷-位移软化曲线。此外，混合模式双边缘缺口试样的 3D 结果表明，即使使用较粗的网格，所提出的模型也能提供良好的结果，所使用的元素比最近的文献和类似结果少 16 倍。