Abstract As a non-contact optical experimental method, caustic method is commonly employed in measuring stress intensity factor at the crack tips of different materials. Caustics theory is commonly used for solving stress intensity factor at crack tips in homogeneous isotropic materials, but it lacks the required accuracy for solving stress intensity factor in interfacial cracks in dissimilar materials. In this paper, we have deduced the theoretical equation of stress intensity factor at interfacial crack tips the orthotropic bi-materials and evaluated the effects of different crack propagation speeds, orthotropic bi-materials and other parameters on the initial curves of focal line and the shape of caustics. In addition, dynamic caustic experiments on composite/epoxy bi-materials under low velocity-impact loadings were performed and the evolution of dynamic interfacial cracks was captured by high-speed cameras which showed good agreements with theoretical results. Research results confirmed the usefulness of the application of caustic method in dissimilar isotropic and orthotropic materials, isotropic-orthotropic bi-materials and homogeneous isotropic and orthotropic materials under subsonic crack propagation velocities.

中文翻译：

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界面裂纹焦散法统一理论模型

摘要 焦散法作为一种非接触式光学实验方法，常用于测量不同材料裂纹尖端的应力强度因子。焦散理论通常用于求解均质各向同性材料裂纹尖端的应力强度因子，但它缺乏求解异种材料界面裂纹应力强度因子所需的精度。本文推导了正交各向异性双材料界面裂纹尖端应力强度因子的理论方程，并评价了不同裂纹扩展速度、正交各向异性双材料等参数对焦线初始曲线和形状的影响。焦散。此外，对复合材料/环氧树脂双材料在低速冲击载荷下进行动态腐蚀性实验，高速相机捕捉到动态界面裂纹的演变，与理论结果吻合良好。研究结果证实了在亚音速裂纹扩展速度下，焦散法在不同的各向同性和正交各向异性材料、各向同性-正交各向异性双材料以及均质各向同性和正交各向异性材料中的应用是有用的。