Abstract The change in the critical strain energy release rate as damage evolves, known as the R-curve, is of crucial importance to the understanding of fracture behaviour. The examination of damage evolution ahead of the crack tip in order to determine accurately the crack increment is key for the determination of the R-curve. Conventional in situ methods such as optical measurements only examine the specimen surfaces. X-ray Computed Tomography (CT) offers satisfactory image quality, but conventional CT scanning requires the removal of the specimens from the test machine. If no dye penetrant is used, the specimens can be re-loaded, but some important information will be missing such as the early load drops corresponding to damage initiation. If dye penetrant is used, the specimens can no longer be re-tested. In contrast, in situ CT scanning can capture the detailed damage states ply-by-ply while the specimen is loaded and diminish the need for multiple specimens. In situ characterization of trans-laminar fracture toughness of composites using CT has not been attempted in the past. It has been proven successful in this research, and shown that a partial R-curve can be constructed with a single Extended Single-Edge-notch Tension (ESET) specimen.

中文翻译：

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使用 X 射线计算机断层扫描原位表征跨层断裂韧性

摘要 随着损伤的发展，临界应变能释放率的变化，称为 R 曲线，对于理解断裂行为至关重要。检查裂纹尖端之前的损伤演化以准确确定裂纹增量是确定 R 曲线的关键。传统的原位方法（例如光学测量）仅检查样品表面。X 射线计算机断层扫描 (CT) 提供令人满意的图像质量，但传统的 CT 扫描需要从测试机器中取出样本。如果不使用染料渗透剂，样品可以重新加载，但一些重要信息将丢失，例如与损坏开始相对应的早期负载下降。如果使用染料渗透剂，则不能再重新测试样品。相比之下，原位 CT 扫描可以在加载试样时逐层捕获详细的损坏状态，并减少对多个试样的需求。过去没有尝试使用 CT 对复合材料的跨层断裂韧性进行原位表征。该研究已被证明是成功的，并表明可以使用单个扩展单边缘缺口张力 (ESET) 试样构建部分 R 曲线。