不同缝高比下高延性水泥基复合材料Ⅰ-Ⅱ复合型断裂性能模拟研究

Study on simulation of mixed-mode Ⅰ-Ⅱ fracture behavior of engineered cementitious composites with different notch-depth ratios

  • 摘要: 为探究缝高比影响下高延性水泥基复合材料(engineered cementitious composites, ECC)Ⅰ-Ⅱ复合型断裂性能演化规律,依托ABAQUS分析平台,结合损伤塑性模型(concrete damage plasticity, CDP)与单元删除技术,建立ECC三点弯曲梁数值模型,通过对比模拟与试验所得荷载-裂缝张开位移曲线、裂缝扩展路径等,验证了模拟的有效性。选取4种初始缝高比分别为0.1、0.2、0.3、0.4的试件,建立有限元分析模型,从破坏形态、荷载特征、断裂韧度等维度分析缝高比对Ⅰ-Ⅱ复合型断裂性能的影响。结果表明:试件从预制裂尖起裂,后向试件上表面偏转延伸,最终形成明显偏斜的Ⅰ-Ⅱ复合型贯通裂缝,但并未到达加载点;随着初始缝高比的增大,起裂荷载、失稳荷载及断裂韧度逐步降低;模拟过程可体现Ⅰ-Ⅱ复合型裂缝扩展过程的3个阶段。

     

    Abstract: In order to explore the evolution law of mixed-mode Ⅰ-Ⅱ fracture properties of engineered cementitious composites (ECC) under the influence of notch-depth ratio, a numerical model of three-point bending ECC beams was established based on the ABAQUS analysis platform, combined with the concrete damage plasticity (CDP) model and element deletion technique. The validity of the simulation was verified by comparing the load-crack opening displacement curves and crack propagation paths obtained from both simulation and experimental results. Four specimens with different initial notch-depth ratios of 0.1, 0.2, 0.3, 0.4 were selected to establish the finite element analysis model. The influence of the notch-depth ratio on the mixed-mode Ⅰ-Ⅱ fracture properties was systematically analyzed from the aspects such as failure mode, load characteristics, and fracture toughness. The results showed that the specimen cracked from the pre-fabricated notch tip, then extended towards the upper surface of the specimen and finally formed a significantly deviated mixed-mode Ⅰ-Ⅱ through crack, but it did not reach the loading point. As the initial notch-depth ratio increased, the initial load, unstable load and toughness gradually decreased. The simulation process can reflect the three-stage propagation process of the mixed-mode Ⅰ-Ⅱ fracture.

     

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