Abstract
Polyurethane adhesive and aluminum alloy were selected to make adhesive joints. Butt joints tested at different loading angles (0°, 45°, and 90°) using a modified Arcan fixture were selected to represent three stress states (normal stress, normal/shear combined stress, and shear stress, respectively). Firstly, the accelerated aging tests were carried out on the joints in a hygrothermal environment (80 °C/95% RH). The quasi-static tests were carried out at different temperatures (−40 °C, 20 °C, and 80 °C) for the joints after hygrothermal aging for different periods. The variation rules of the joints’ mechanical properties and failure modes with different aging levels were studied. The results show that the failure load of the joints was obviously affected by stress state and temperature. In the low-temperature test, the failure load of the joints decreased most obviously, and the BJ was the most sensitive to temperature, indicating that the failure load decreased more with the increase of the normal stress ratio in the joint. Through macroscopic and SEM analysis of the failure section, it was found that the hydrolysis reaction of polyurethane adhesive itself and the interface failure of the joints were the main reasons for the decrease of joint strength. The failure models were established to characterize the adhesive structure with different aging levels at service temperature.
Highlights
Adhesion technology has been widely used in the assembly process of high-speed train components
When the quasi-static mechanical properties of the adhesive joints after hygrothermal aging were tested at three temperatures (−40 °C, 20 °C, and 80 °C), the obtained me
It is found average of agi for 6 days, the failure loads obviously decrease; this is becausethat thethe polymer chain b failure loads of joints decrease graduallyin with increase ofrange aging time, and there areunder d and there aretheapparent differences thethevariation of failure load for the longest duration, the fastest speed, anddifferent the fastest decreasing cro apparent differences the variation rangebreaking of failure load under temperatures temperatures andindifferent stress states
Summary
Adhesion technology has been widely used in the assembly process of high-speed train components. In the service process of the high-speed trains, the adhesive structure is more vulnerable to the comprehensive effect of environmental factors, such as temperature and humidity. Domestic and foreign scholars have carried out relevant research found that the aging behavior of the adhesive system in the service process of the highon the influence of hygrothermal aging on adhesive structures’ strength property. It was speed trains was usually the result of the combined effect of temperature and humidity. The failure criteria related to aging cycle and temperature were obtained, which could be used to check the strength under different aging levels and temperatures
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