环境温湿度对泡沫复合材料夹层结构界面性能的影响

摘要

复合材料夹层结构是由复合材料作为面板、轻质材料作为芯材而形成的强度高、耐腐性好、可设计性强的高效结构形式.环境温湿度变化时,因面板和芯材的吸湿性能和热膨胀系数不同,界面处易积聚应力而导致剥离破坏.本文研究不同时间的干湿循环老化作用下泡沫复合材料夹层结构及其面板、芯材的吸湿性能,达到吸湿平衡时,芯材的吸湿率是面板的10倍左右;由于双侧面板的约束作用,夹层结构与面板的吸湿率相当.通过双悬臂梁界面剥离拉伸试验研究干湿循环老化构件在25和70℃两种温度环境条件下的界面性能,从试验所得的荷载-位移曲线可以看出:结构的界面强度随老化时间的延长而降低;温度对老化构件的界面力学性能影响显著,温度越高,界面强度越低,裂纹扩展越稳定.%Composite sandwich structures,formed by two stiff face sheets sandwiching a light weight core, have many advantages such as high strength,excellent corrosion resistance,and good design-ability.Due to the discontinuous moisture absorption properties and thermal expansion coefficients, the interfacial delamination often occurred in practical engineering under varying temperature and humidity. This paper focuses on the moisture absorption performance of foam-core sandwich structures subjected to dry-wet cycle environment.It is found that the moisture rate of core is almost 10 times as high as that of the face sheet when the sandwich is in moisture sorption equilibrium. In the process of moisture absorption, the moisture rate of sandwich is the same as that of the face sheet,because of the constraint of the face sheets. By using the stretch tests for double cantilever beam,the interfacial performance under 25 and 70 ℃ are investigated.The results indicate that the interfacial strength decreases with the increase in aging time. Moreover,the temperature can affect the interfacial performance.The interfacial strength decreases and the crack propagations tend to be stable under high temperatures.