ABSTRACT

Today, adhesively bonded joints are frequently used in the space and aviation industries. Joints used in these sectors are generally subject to dynamic loads due to environmental factors. This study experimentally and numerically investigated the static tensile loads of adhesively bonded joints after fully reversed (combination of tensile and compressive) fatigue loading where nanoadhesives – obtained by adding carbon nanostructures into aerospace grade structural adhesive – were used to bond the joints. Single lap joint specimens were produced using a nanocomposite adhesive obtained by adding 1 wt. % graphene, 1 wt. % carbon nanotubes-COOH and 1 wt. % fullerene C60 nanostructures to a DP460 structural adhesive. AA2024-T3 aluminum alloy and carbon fiber-reinforced composites (CFRCs) with a plain weave fabric (0/90°) were used as adherend materials. First, static tensile tests were applied to these joints to obtain their failure loads and then fully reversed sinusoidal fatigue tests were applied under a constant load amplitude, a frequency of 20 Hz and a load ratio of R = −1. Considering the failure loads obtained from the static tensile tests, 10⁶ fully reversed fatigue loading cycles were applied – which was accepted as an infinite life – at 400 N, 800 N and 1200 N load levels.

The static tensile failure loads and energy values absorbed of these joints were obtained and the change in the failure loads and energy values absorbed of the joints subjected to fatigue was investigated. The static failure loads of aluminum joints bonded with nanoadhesive and subjected to fully reversed fatigue loading increased by approximately 5% to 17%, depending on the nanostructure type added to the adhesive. Moreover, it was observed that there was an increase in loading of approximately 3% to 20% for the nanostructure reinforced joints obtained by using CFRCs with [0/90]₆ stacking sequence.

摘要

今天，粘合接头经常用于航天和航空工业。由于环境因素，这些领域中使用的接头通常会承受动态载荷。本研究通过实验和数值方法研究了在完全逆转（拉伸和压缩的组合）疲劳载荷后粘合接头的静态拉伸载荷，其中纳米粘合剂（通过将碳纳米结构添加到航空级结构粘合剂中获得）用于粘合接头。使用通过添加 1 wt. % 石墨烯, 1 wt. % 碳纳米管-COOH 和 1 wt. % 富勒烯 C60 纳米结构到 DP460 结构粘合剂。AA2024-T3 铝合金和碳纤维增强复合材料 (CFRCs) 与平纹织物 (0/90°) 被用作粘附材料。首先，对这些接头进行静态拉伸试验以获得它们的失效载荷，然后在恒定载荷幅值、20 Hz 频率和 R = -1 载荷比下进行完全反向正弦疲劳试验。考虑从静态拉伸试验获得的破坏载荷，10^{在 400 N、800 N 和 1200 N 载荷水平下应用了6 个}完全反向的疲劳载荷循环——这被认为是无限寿命。

获得了这些接头的静态拉伸破坏载荷和吸收能量值，并研究了疲劳接头的破坏载荷和吸收能量值的变化。与纳米粘合剂粘合并承受完全反向疲劳载荷的铝接头的静态失效载荷增加了大约 5% 至 17%，具体取决于添加到粘合剂中的纳米结构类型。_{此外，观察到使用具有 [0/90] 6}堆叠顺序的 CFRC 获得的纳米结构增强接头的负载增加了大约 3% 到 20% 。