Abstract In this paper an inclined edge cracked short beam specimen subjected to symmetric three-point bend loading was designed and examined for conducting mixed-mode I/II fracture toughness experiments. The aspect ratio (i.e. length to width ratio) and the loading span distance are considered much lower than the other conventional cracked bend beam samples. Crack tip parameters such as stress intensity factors and T-stress were computed numerically for this specimen by several finite element analyses and it was demonstrated that the specimen is able to produce full combinations of mode I and II including pure mode II. The practical capability of the short bend beam specimen was studied experimentally by conducting a set of mixed-mode fracture tests on PolymethylMethacrylate (PMMA) as a well-known model brittle material. The critical stress intensity factors, the direction of fracture kinking and the path of fracture trajectory were investigated both experimentally and theoretically using two stress and strain-based fracture criteria. The fracture toughness of tested PMMA was decreased by moving towards mode II case due to the effect of T-stress on the fracture mechanism of the short bend beam specimen.

中文翻译：

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边缘裂纹短弯梁试件在混合模式 I/II 下 PMMA 断裂韧性测试中的应用

摘要 本文设计并检验了受对称三点弯曲载荷作用的倾斜边缘裂纹短梁试样，以进行混合模式 I/II 断裂韧性试验。纵横比（即长宽比）和加载跨距被认为远低于其他常规裂纹弯曲梁样品。裂纹尖端参数，如应力强度因子和 T 应力，通过几次有限元分析对该试样进行了数值计算，并证明该试样能够产生模式 I 和 II 的完整组合，包括纯模式 II。通过对聚甲基丙烯酸甲酯 (PMMA) 作为一种众所周知的模型脆性材料进行一组混合模式断裂试验，对短弯曲梁试样的实际能力进行了实验研究。使用两种基于应力和应变的断裂标准，通过实验和理论研究了临界应力强度因子、断裂扭结方向和断裂轨迹路径。由于 T 应力对短弯曲梁试样断裂机制的影响，测试 PMMA 的断裂韧性通过向模式 II 情况移动而降低。