吸水/失水对GFRP层压板弯曲性能的影响

Moisture absorption/desorption effects on flexural properties of GFRP laminates

摘要:

为研究湿热软化环境中吸水/失水对玻璃纤维增强聚合物（GFRP）层压板弯曲性能退化的影响,进行了三点弯曲试验,对分别在20 ℃和40 ℃环境中测得的干燥、不饱和吸水与饱和吸水试件的弯曲性能进行了比较分析。以一次吸水-失水过程为一个周期,来研究由水分扩散引起的GFRP层压板力学性能退化程度和永久损伤。试验结果表明:湿热组合效应会使GFRP层压板的抗弯强度和弹性模量降低,且抗弯强度的降低率远大于弹性模量的降低率；在40 ℃环境下,经一个周期处理后,GFRP层压板的弹性模量和抗弯强度相比原始试件均产生了不可恢复的损失,分别为15.0%和16.4%,而这种损失在20 ℃下并不明显。此外,建立了湿-力耦合有限元模型,以模拟GFRP层压板在不同吸水/失水阶段的力学性能,并通过弯曲试验进行验证。

Abstract:

To investigate the influence of moisture absorption/desorption on the flexural property degradation of glass fiber reinforced polymer (GFRP) laminates under hot/wet aging environments, three-point bending tests were carried out. The flexural properties of specimens were compared under dry, unsaturated, and saturated water absorption conditions at test temperatures 20 ℃ and 40 ℃. A moisture absorption-desorption process was considered as a cycle to investigate the mechanical degradation and permanent damage of GFRP laminates induced by moisture diffusion. Experimental results show that the combination effects of moisture and temperature reduced the flexural strength and elastic modulus of GFRP laminates, and the reduction rate of flexural strength was much larger than that of elastic modulus. At the test temperature of 40 ℃, unrecoverable losses of elastic modulus (15.0%) and flexural strength (16.4%) occurred for GFRP laminates experiencing one cycle of moisture absorption-desorption process, which was not evident at the test temperature of 20 ℃.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 was subsequently validated with flexural test results.