Abstract In this study, based on an experimental digital laser dynamic caustic system, a dynamic fracture experiment on a polymethyl methacrylate (PMMA) semi-disc specimen with a weak precast double-layer surface under an impact load was carried out, the cracking, expansion, and wearing patterns of the cracks under different tilt angles (60°, 45°, and 30°) were studied, and the changing characteristics of the trajectory, velocity, and dynamic stress intensity factors of a crack expansion were compared. In addition, a newly developed discrete lattice spring method was adopted to simulate the expansion of dynamic cracks in a PMMA specimen with weak double-layer surfaces, and it was found that this numerical model can reproduce experimental phenomena for analyzing the effects of a weak surface spacing on the crack expansion. Combined with the test and numerical analysis results, it can be concluded that the tilt angle and spacing of a weak double-layer surface will have a significant influence on the crack expansion characteristics.

中文翻译：

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动态荷载作用下预制双层弱表面半圆盘聚甲基丙烯酸甲酯试样的裂纹扩展特性研究

摘要 本研究基于实验性数字激光动态焦散系统，对具有弱预制双层表面的聚甲基丙烯酸甲酯（PMMA）半圆盘试样在冲击载荷作用下进行动态断裂试验，断裂、膨胀、膨胀。 ,研究了不同倾斜角度(60°、45°和30°)下裂纹的磨损规律,比较了裂纹扩展轨迹、速度和动态应力强度因子的变化特征。此外，采用新开发的离散晶格弹簧方法模拟具有弱双层表面的 PMMA 试样中动态裂纹的扩展，发现该数值模型可以再现实验现象，用于分析弱表面的影响裂纹扩展的间距。