石英纤维增强聚酰亚胺树脂基复合材料的疲劳特性

Fatigue performance of quartz fiber/polyimide composite at elevated temperature

石英纤维增强聚酰亚胺树脂基复合材料具有比强度高、比刚度大、结构可设计性等很多优点,将在武器装备结构件领域广泛应用。对石英纤维增强聚酰亚胺树脂基复合材料的室温及高温拉伸性能进行了研究;对石英纤维增强聚酰亚胺树脂基复合材料的室温及高温拉-拉疲劳特性进行了研究。结果表明,复合材料的拉伸强度及弹性模量随着测试温度的升高而降低,并且在300℃时保留率分别是68%和80%。在相同应力水平下,复合材料的室温疲劳寿命比高温疲劳寿命高。在高温下,由于树脂软化,复合材料的经纱裂纹减缓。通过疲劳断裂的断口形貌和疲劳寿命变化,对复合材料损伤机制进行评估。

The tensile stress-strain behavior and tensile strength of quartz fiber reinforced polyimide matrix (QFRP) composite were measured at room and elevated temperatures.The average tensile strength and elasticity modulus decreased with increasing temperature,and remained 68% and 80% at 300℃,respectively.Tension-tension fatigue behavior of a QFRP composite was studied at room and elevated temperatures.At the same cyclic stress level,a longer fatigue life of QFRP composites was obtained at room temperature,compared to elevated temperature.Damage evolution was discussed on the basis of cross-section and mechanical variation.The dominant damage mechanism of warp yarn cracking was mitigated at elevated temperatures as a direct result of resin softening,which was also the case for the fatigue test specimens.This study yielded an improved understanding of damage mechanisms and local deformation behavior for QFRP composite,which was valuable for designers.