压-压疲劳载荷下CFRP层合板表面红外辐射特征

为探究含冲击损伤CFRP层合板在循环交变载荷下的损伤演化规律，基于热力耦合效应研究了含损伤CFRP层合板疲劳过程中的表面红外辐射特征。以压-压疲劳试验模拟交变载荷，采用红外热成像方法分析了疲劳过程中含损伤CFRP层合板的热图序列和温度数据，结果表明：随着疲劳次数的增加，损伤沿垂直疲劳载荷方向演化，热斑颜色逐渐加深，初始冲击损伤形状逐渐演化为椭圆状，最后热斑横向端部出现"尖点"；试件最大表面温差演化整体呈"快速上升-缓慢上升-快速上升"规律，最后出现跳升，其中热斑尖点、最大表面温差跳升可被视为结构疲劳破坏的前兆；含损伤CFRP层合板疲劳破坏时，其最大表面温差主要与纤维和基体种类有关，而试件铺层方式相较于纤维基体类别对最大表面温差无明显影响。研究揭示了冲击后CFRP层合板在疲劳载荷作用下的损伤演化规律，为飞行器复合材料结构的剩余疲劳寿命评估与损伤容限设计奠定了基础。

Infrared radiation characteristics of CFRP laminate surface under compressive fatigue load

To explore the damage evolution rule of impact-damaged CFRP laminates under cyclic alternating load, we studied the surface infrared radiation characteristics of damaged CFRP laminates during fatigue based on the thermodynamic coupling effect. Using the infrared thermal image method, we analyzed the heat map sequences and temperature data of the damaged CFRP laminated plate during fatigue with the pressure-pressure fatigue test simulating the alternating load. Results show that with the increase of fatigue times, the damage evolves along the vertical direction of the fatigue load, the color of the hot spot gradually deepens, the initial impact damage slowly evolves into an elliptical shape, and finally a "sharp point" appears at the end of the hot spot. The maximum surface temperature difference of the specimen as a whole shows the rule of "fast rise-slow rise-fast rise", finally leading to a jump. The "sharp point" on the hot spot and the maximum surface temperature difference jump can be regarded as the precursor of structural fatigue failure. When the CFRP laminates are damaged, the maximum surface temperature difference is mainly related to the types of the fiber and the matrix, while the laying-out mode of the specimens has no significant influence on the types of fiber matrix. The study reveals the damage evolution law of CFRP laminates under fatigue load after impact, laying a foundation for the residual fatigue life evaluation and damage tolerance design of aircraft composite structures.