This paper presents the outcomes of a research program that tested and examined the behaviors of glass fiber-reinforced polymer (GFRP) bonded steel double-strap joints after being cured in a variety of harsh curing conditions. Nineteen specimens were manufactured, cured in an air environment (the reference specimen), treated with different wet–dry cyclic curing or hygrothermal pretreatment, and then tested under quasi-static loading. Based on the experimental studies, mixed failure modes, rather than the cohesive failure of the adhesive, were found in the harsh environmental cured specimens. Additionally, an approximately linear relationship of load–displacement curves was observed for all the GFRP/steel bonded specimens from which the tensile capacities and stiffness were discussed. By analyzing the strain development of the bonded specimens during quasi-static tensile testing, the fracture mechanism analysis focused on the threshold value of the strain curves for different cured specimens. Finally, based on the studies of interfacial fracture energy, G_f, the effects of harsh environmental curing were assessed. The results showed that the failure modes, joint tensile capacities, stiffness, and interfacial fracture energy G_f were highly dependent on the curing conditions, and a significant degradation of bonding performance could be introduced by the investigated harsh environments.

中文翻译：

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干湿循环和湿热固化后GFRP /钢粘结接头的粘结行为

本文介绍了一项研究计划的结果，该计划在各种恶劣的固化条件下进行固化后，测试并检查了玻璃纤维增​​强聚合物（GFRP）粘结的钢双表带接头的行为。制造了19个样品，在空气环境中固化（参考样品），用不同的干湿循环固化或湿热预处理进行处理，然后在准静态载荷下进行测试。根据实验研究，在恶劣的环境固化标本中发现了混合破坏模式，而不是粘合剂的内聚破坏。此外，对于所有GFRP /钢粘结试样，观察到了载荷-位移曲线的近似线性关系，并从中讨论了其抗拉能力和刚度。通过分析准静态拉伸试验过程中粘结试样的应变发展，断裂机理分析集中在不同固化试样的应变曲线阈值上。最后，基于界面断裂能的研究，G _f，评估了恶劣环境固化的影响。结果表明，破坏模式，接头抗拉能力，刚度和界面断裂能G _f高度依赖于固化条件，并且所研究的恶劣环境可能导致粘结性能的显着降低。