湿热环境下碳纤维复合材料斜面胶接件拉伸试验研究

Tensile performance of adhesively bonded carbon/epoxy composite scarf joints subject to hygrothermal environment

测量了胶膜及其复合材料斜面胶接件在湿热环境下的力学性能,对比分析了湿热环境对胶膜及其碳纤维复合材料斜面胶接件力学性能的影响,并分析了湿热对其破坏模式的影响。研究表明,胶膜的模量和强度吸湿后分别下降23.6%和27.0%,高温下分别下降69.4%和66.9%,吸湿后高温下分别下降85.0%和89.0%;其碳纤维复合材料斜面胶接件的名义剪切强度在吸湿后、高温下和吸湿后高温下分别下降了12.6%、36.4%和78.1%。同时,该斜面胶接结构的失效模式在室温干态时胶层和胶接界面破坏都有;吸湿致使胶接界面性能下降而发生更多界面破坏;高温环境下,以胶层破坏为主;湿热同时作用下,以界面破坏为主。

Experiments were carried out to test the tensile properties of adhesive film and adhesively bonded carbon/epoxy composite scarf joints using this adhesive film under different environment conditions. Comparisons were then made to study the hygrothermal effects on their mechanical properties. Changes of damage modes induced by hygrothermal environments were analyzed. Results showed degradations of the modulus and strength of adhesive were 23.6% and 27.0%, respectively, after water absorption; 69.4% and 66.9%, respectively, under elevated temperature; 85.0% and 89.0%, respectively, under combination of water absorption and elevated temperature. The nominal shear strength of carbon/epoxy composite scarf joints decreased 12.6%, 36.4% and 78.1%, for room temperature/wet, elevated temperature/dry and elevated temperature/wet condition respectively. Simultaneously, both adhesive and interfacial failures happened under room temperature/dry condition. After water absorption, the strength of interface between adhesive and laminate was degraded and more interfacial fracture generated. Adhesive properties decreased a lot under elevated temperature, so adhesive failure dominated. While subject to combination of elevated temperature and wet condition, interfacial fracture dominated.