湿热环境下复合材料的混合型层间断裂特性研究

EXPERIMENTAL STUDY ON THE INTERLAMINAR FRACTURE TOUGHNESS OF COMPOSITE LAMINATE ON HYGROTHERMAL CONDITIONS

采用混合型挠曲(MMF)试件,研究了材料吸湿和环境温度对T300/5405复合材料混合型层间断裂韧性的影响。给出了在不同温度下,不同吸湿含量试件分层临界扩展时的 型分量和 型能量释放率分量散点图。结果表明:在吸湿和温度的综合作用下,分层尖端存在塑性变形;常温下,吸湿对材料的层间断裂韧性影响不明显,在高温环境中,随吸湿量增加,层间断裂韧性显著增加;温度对干态材料的断裂韧性影响较小,试件吸湿后,随温度升高,韧性增强。

With mixed-mode flexure (MMF) specimens, the mixed-mode interlaminar fracture toughness of composite laminate was investigated experimentally, mainly focused on the hygrothermal effect on the strain energy release rates. It was found that the co-function of heat and moisture caused plasticity near the tip of delamination. The critical energy release rates were calculated with two expressions (for mode I and mode II components, respectively) based on the beam theory. Scatter graphs of GI versus GII, the mode I and mode II components of critical energy release rates in different hygrothermal conditions, were given. The result showed that at room temperature, the hygroscopic absorption had little effect on the interlaminar fracture toughness, while at higher temperature conditions, the toughness increased as the hygroscopic degree increased. For dry laminates, the fracture toughness showed no distinct difference as the temperature increased, and for highly moisture absorbted specimens, the toughness was improved markedly. The fractograph was examined for further understanding of the mechanism.