Free-edge effects in fibre reinforced composites can produce premature damage at the composite edges due to mechanical, geometrical and hygro–thermal effects. Observation of damage on the free-edge of a composite plate is therefore different than what can be observed inside the material. The amount of individually broken fibres in a composite is counted by observing a test specimen with a polished edge and by cutting test specimens to observe damage inside the material. The amount of damage observed on a polished edge is found to greatly exceed that which is observed inside test specimens subjected to the same testing conditions. It is shown that the progression of important damage mechanisms can be observed on polished edges, but also that invalid damage mechanism may be observed using free-edge microscopy.

中文翻译：

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使用大视场显微镜观察复合材料弯曲疲劳试验中的边缘效应

由于机械、几何和湿热效应，纤维增强复合材料中的自由边缘效应会在复合材料边缘产生过早损坏。因此，观察复合板自由边缘的损伤与观察到的材料内部不同。通过观察具有抛光边缘的试样和切割试样以观察材料内部的损坏来计算复合材料中单个断裂纤维的数量。发现在抛光边缘上观察到的损伤量大大超过在相同测试条件下的试样内部观察到的损伤量。结果表明，可以在抛光边缘上观察到重要损伤机制的进展，但也可以使用自由边缘显微镜观察到无效的损伤机制。