碳纤维树脂基复合材料三点弯曲超高周疲劳实验研究

STUDY ON THE THREE-PIONT BENDING FATIFGUE EXPERIMENT OF CARBON FIBER REINFORCED RESIN COMPOSITEES IN THE VERY HIGH CYCLE FATIGUE REGIME

开展了碳纤维树脂基复合材料三点弯曲超高周疲劳实验,对比了无冷却、间断加载、压缩冷空气及液氮四种冷却方式,并利用红外热像仪对试件的温度进行监控,研究了碳纤维树脂基复合材料在超声频加载下的热效应。结果表明:碳纤维树脂基复合材料在超声频加载时会产生明显的温升现象,并对其弯曲模量及谐振频率产生较大影响,严重时甚至会出现试件烧蚀现象;采用液氮冷却可保证试件在超声加载过程中温度不超过其玻璃态转化温度;当应力循环次数超过10~7时试件在超高周范围仍会发生疲劳破坏,破坏形式包括分层、基体开裂两种。

The three-point bending fatigue experiment of CFRP was carried out.The four cooling methods including no cooling,discontinuous load,compressed cold air and liquid nitrogen cooling were compared.The thermal effect of ultrasonic loading for CFRP was studied by using the infrared thermal imager to detect temperature of the specimens.Results show that the temperature of CFRP in ultrasonic loading would rise obviously,as a result,the bending modulus and resonance frequency will be greatly influenced,even the specimens can be ablated.And the cooling method using liquid nitrogen can guarantee that the temperature of the specimen will not exceed the glass transition temperature under ultrasonic loading.Composite will still be destroyed in very high cycle regime.The fatigue characteristics of the composite were lamination and matrix cracking.