Jiang Xu, Song Jie, Qiang Xuhong, Kolstein Henk, Bijlaard Frans
Department of Bridge Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China.
Shandong Provincial Academy of Building Research, Jinan 250031, China.
Polymers (Basel). 2016 Aug 10;8(8):290. doi: 10.3390/polym8080290.
Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP) laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test standard (ASTM D790-10A). The flexural properties of dry (0% /), moisture unsaturated (30% / and 50% /) and moisture saturated (100% /) specimens at both 20 and 40 °C test temperatures were compared. One cycle of moisture absorption-desorption process was considered in this study to investigate the mechanical degradation scale and the permanent damage of GFRP laminates induced by moisture diffusion. Experimental results confirm that the combination of moisture and temperature effects sincerely deteriorates the flexural properties of GFRP laminates, on both strength and stiffness. Furthermore, the reducing percentage of flexural strength is found much larger than that of E-modulus. Unrecoverable losses of E-modulus (15.0%) and flexural strength (16.4%) for the GFRP laminates experiencing one cycle of moisture absorption/desorption process are evident at the test temperature of 40 °C, but not for the case of 20 °C test temperature. Moreover, a coupled hygro-mechanical Finite Element (FE) model was developed to characterize the mechanical behaviors of GFRP laminates at different moisture absorption/desorption stages, and the modeling method was subsequently validated with flexural test results.
在热湿老化环境下，通过实验研究了吸湿/解吸对玻璃纤维增强聚合物（GFRP）层压板弯曲性能的影响。为了表征机械降解，按照美国材料与试验协会（ASTM）测试标准（ASTM D790 - 10A）进行了三点弯曲试验。比较了在20℃和40℃测试温度下，干燥（0%/）、吸湿不饱和（30%/和50%/）以及吸湿饱和（100%/）试样的弯曲性能。本研究考虑了一个吸湿 - 解吸过程循环，以研究水分扩散引起的GFRP层压板的机械降解程度和永久性损伤。实验结果证实，湿度和温度效应的共同作用确实会使GFRP层压板的弯曲性能在强度和刚度方面都有所下降。此外，发现弯曲强度的降低百分比远大于弹性模量的降低百分比。在40℃测试温度下，经历一个吸湿/解吸过程循环的GFRP层压板的弹性模量不可恢复损失（15.0%）和弯曲强度不可恢复损失（16.4%）很明显，但在20℃测试温度下并非如此。此外，还建立了一个耦合的湿热 - 力学有限元（FE）模型来表征GFRP层压板在不同吸湿/解吸阶段的力学行为，随后用弯曲试验结果对建模方法进行了验证。
