Abstract Thin barrier coatings on polymer films are used increasingly in various applications. In coatings development, it is of interest to characterise the fracture toughness. The tensile fragmentation test potentially provides data to determine the critical energy-release rate for channelling cracks in the coatings during crack accumulation with increasing strain. Also, the crack-opening of displacement is of importance to predict barrier properties. In this work, a method based on finite-element simulations is presented to predict the energy-release rate and crack-opening displacement. The results are compared with experimental findings for TiO2 and mixed TiO2-Al2O3 coatings, with a thickness down to 4–20 nm, on polymer films. It was found that the non-linear stress–strain behaviour of the polymer substrate material needs to be accounted for in the numerical model, in particular for the high strains close to crack saturation observed in these types of materials. Considering the small scales for the cracks and coating thickness, the predicted crack openings compare favourably with those measured experimentally using high-resolution scanning-electron microscopy.

中文翻译：

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承受拉伸载荷的聚合物基材上的薄屏障涂层中的能量释放速率和裂纹的张开

摘要 聚合物薄膜上的薄屏障涂层越来越多地用于各种应用。在涂层开发中，表征断裂韧性很重要。拉伸断裂试验可能提供数据，以确定在随着应变增加裂纹积累过程中涂层中沟道裂纹的临界能量释放率。此外，位移的裂缝张开对于预测屏障性能很重要。在这项工作中，提出了一种基于有限元模拟的方法来预测能量释放率和裂缝张开位移。将结果与聚合物薄膜上的 TiO2 和混合 TiO2-Al2O3 涂层（厚度低至 4-20 nm）的实验结果进行比较。研究发现，聚合物基材的非线性应力-应变行为需要在数值模型中加以考虑，特别是对于在这些类型的材料中观察到的接近裂纹饱和的高应变。考虑到裂纹和涂层厚度的小尺度，预测的裂纹开口与使用高分辨率扫描电子显微镜实验测量的那些相比更有利。