ABSTRACT

The mechanical properties of adhesives are sensitive to both temperature and humidity. A modified Arcan device was proposed to characterize the failures of adhesive joints under mixed mode loading. Aluminum alloy butt joints (BJs), 45°scarf joints (45°SJs) and thick-adherend shear joints (TASJs) were manufactured to investigate the effects of loading conditions. Moreover, these joints were subjected to various durations of high-temperature aging (80°C) and hygrothermal aging (80°C/95% RH): 0 (unaged), 6, 12, 18, 24, and 30 days. The adhesive joints were analyzed by Fourier transform infrared (FTIR) spectroscopy, and the load–displacement curves, failure strengths, failure modes were analyzed. The results showed under high-temperature conditions, humidity can accelerate the rate of decrease in the failure strength of the adhesive joints, which resulted from the fracture of the polymer chains and the influence of internal stresses. As the hygrothermal aging duration increased, the fracture surfaces of the joints changed significantly. The number of cracks and cavities in the fracture surface increased as the aging duration increased. After aging, the failure strength values of the adhesive joints conformed to the quadratic stress failure criterion. Two curved surface equations reflecting the relationship between the quadratic stress criterion and the aging duration were established.

摘要

粘合剂的机械性能对温度和湿度都很敏感。提出了一种改进的 Arcan 装置来表征混合模式载荷下粘合接头的失效。制造铝合金对接接头 (BJs)、45°scarf 接头 (45°SJs) 和厚粘附剪切接头 (TASJs) 以研究加载条件的影响。此外，这些接头经受了不同时间的高温老化 (80°C) 和湿热老化 (80°C/95% RH)：0（未老化）、6、12、18、24 和 30 天。采用傅里叶变换红外（FTIR）光谱分析粘接接头，分析载荷-位移曲线、失效强度、失效模式。结果表明，在高温条件下，湿度会加速胶接头破坏强度的下降速度，这是由于聚合物链的断裂和内应力的影响。随着湿热老化时间的延长，接头断口发生明显变化。随着时效时间的增加，断口中裂纹和空洞的数量增加。老化后，粘接接头的破坏强度值符合二次应力破坏准则。建立了反映二次应力判据与时效时间关系的两个曲面方程。粘接接头的破坏强度值符合二次应力破坏准则。建立了反映二次应力判据与时效时间关系的两个曲面方程。粘接接头的破坏强度值符合二次应力破坏准则。建立了反映二次应力判据与时效时间关系的两个曲面方程。