高温环境对胶螺混合连接复合材料结构失效行为的影响

Effect of elevated temperature on failure behavior of hybrid bolted-bonded joints in composite structures

  • 摘要: 采用试验与仿真相结合的方法,对高温环境下玻璃纤维增强树脂(GFRP)平纹编织层合板-铝合金双钉单搭接胶螺混合连接结构的载荷传递机制和失效模式展开探究。试验方面,开展了80℃高温环境下胶螺混合连接结构的拉伸破坏试验,并与室温胶螺混合连接、高温纯螺栓连接和室温纯螺栓连接三组工况进行对比分析;借助3D-DIC和SEM等手段对结构的宏观和微观的失效特征进行表征。数值仿真方面,构建了基于LaRC失效准则的复合材料渐进损伤失效模型,插入内聚力单元用于对胶粘剂的模拟。结果表明:胶螺混合连接在常温和高温时的极限载荷比纯螺栓连接分别提高了9.2%和4.0%,但高温环境会使胶螺混合连接试样的极限载荷值下降17.8%;胶螺混合连接在加载前期可以缓解应力集中现象,但温度载荷导致粘合剂提前失效后表面出现明显的应力集中,最终失效除了常温环境中发生的静截面拉伸破坏,还发生了由于轴承效应导致的挤压破坏,此时失效模式与纯螺栓连接一致;构建的数值仿真模型可以准确预测结构的失效模式和演化过程,对胶螺混合连接结构的载荷传递机制和失效规律进行解析。

     

    Abstract: Experiments and simulations were conducted to investigate the load transfer mechanism and failure modes of a double-bolt single-lap hybrid bolted-bonded joint between glass fiber reinforced polymer (GFRP) plain weave laminates and an aluminum alloy plane under high-temperature conditions. The experimental aspect involved conducting tensile failure tests on hybrid bolted-bonded joints under high-temperature conditions of 80℃, and comparing them with three other working conditions: Hybrid bolted-bonded joints at room temperature, high-temperature bolted joints, and room temperature bolted joints. Failure characteristics at macroscopic and microscopic scales of the hybrid jointed structure were characterized by means of 3D-DIC and SEM. The numerical simulation involved the development of a progressive damage failure model based on the LaRC failure criterion to accurately depict the evolution of in-plane failures. Additionally, cohesive elements were incorporated between plies to effectively simulate delamination behavior. The results indicate that the hybrid bolted-bonded joint exhibits an increase in ultimate load capacity compared to a bolted joint at both room temperature and elevated temperature, with enhancements of 9.2% and 4.0%, respectively. However, it is noteworthy that the ultimate load capacity of the hybrid bolted-bonded joint specimens is reduced by 17.8% in the elevated temperature environment. The hybrid bolted-bonded joint mitigates stress concentration phenomena during the early stages of loading. However, noticeable stress concentrations occur on the surface under temperature-induced loading after premature adhesive failure. The ultimate failure modes include not only the static cross-sectional tensile failure observed in ambient conditions but also compression failure induced by bearing effects. In this scenario, the failure mode aligns with that of a pure bolted connection. The developed numerical simulation model can accurately predict the failure modes and evolution process of the structure, enabling a comprehensive analysis of the load transfer mechanism and failure patterns in hybrid bolted-bonded joint structures.

     

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