Effect of Humidity on The Fatigue Behaviour of Adhesively Bonded Aluminium Joints

Abstract The present work focuses on the effects of water degradation on the fatigue behaviour of adhesive joints bonded with aluminium adherends. The objective of this study is to measure the influence that humidity has on the fatigue crack growth velocity of two distinct adhesives characterized using the Paris Law, using double cantilever beam (DCB) specimens in unaged and various aged conditions loaded in mode I in order to understand the influence that water content has on the Paris Law constants. It was found that the slope of the Paris Law curve is not heavily changed with the presence of water, but a shift in the curves does occur, generally resulting in a crack initiating at a lower threshold than in the unaged adhesive. Based on this behaviour, it can be concluded that an increase in water content reduces the fatigue joint strength and lifespan of adhesive joints bonded with the studied adhesives.

摘要 本研究聚焦于水降解对铝质被粘物胶接接头疲劳性能的影响。本研究的目标为：采用未老化及多种老化工况下的双悬臂梁（double cantilever beam, DCB）试样，在I型加载条件下，基于巴黎定律（Paris Law）表征两种不同胶粘剂的疲劳裂纹扩展速率，同时探究水分含量对巴黎定律常数的影响机制。研究发现，水的存在对巴黎定律曲线的斜率影响较小，但曲线整体发生偏移，通常表现为相较于未老化胶粘剂，裂纹在更低的临界阈值下萌生。基于该试验现象可得出结论：水分含量的提升会降低所研究胶粘剂胶接接头的疲劳强度与使用寿命。