Evaluation of structural adhesive joints fracture toughness without crack measurement

ABSTRACT The adhesive fracture resistance of structural adhesive joints in mode II, ��IIC, is accessed through the application of two models that prescind of the measurement of the crack length during the subjection of ENF specimens to three-point bending monotonic tests. The load vs transversal displacement results are used in two different approaches: a damage model and a cohesive zone model. The first one was used in test where the crack propagation was unstable and the second one was used for stable crack propagations. These initial results show the viability of the models and show that both: initial crack length and transversal load rate; have great influence in ��IIC evaluation.

摘要 针对结构胶接头的II型粘结断裂韧性（GIIIC），本研究采用两种无需在端部切口弯曲（End Notched Flexure, ENF）试样开展三点弯曲单调加载试验过程中进行裂纹长度测量的模型，完成了相关评估。研究将载荷-横向位移曲线结果应用于两种不同分析路径：损伤模型（damage model）与内聚力区模型（cohesive zone model）。其中损伤模型适配裂纹扩展失稳的试验场景，内聚力区模型则用于裂纹扩展稳定的试验场景。初步研究结果既验证了上述模型的可行性，同时表明初始裂纹长度与横向加载速率均对II型粘结断裂韧性（GIIIC）的评估存在显著影响。