机织热塑性复合材料CF/PPS低速冲击损伤修理工艺参数优化及性能评价

Thermoplastic composites have excellent repairable properties, but the current repair methods for impact damage are not standardized. the phenomenon of stress concentration in the repair area and the influence mechanism of the repair process parameters on the mechanical properties of the repaired materials still need to be further studied. The optimal repair scheme based on different low velocity impact damage characteristics is of great significance to the repair and maintenance of thermoplastic composite structures and performance evaluation. This project firstly carried out low velocity impact test to analyze the impact damage characteristics of CF/PPS of woven thermoplastic composites caused by laminated structures, and quantified the relationship between impact energy and damage repair areas of thermoplastic composites with different laminated structures. Then the finite element modeling of the repaired thermoplastic composite structure is established to analyze the variation law of the stress concentration coefficient in the repair area and the peeling stress of the repair interface with the repair process parameters (the shape of the excavation and the slope of the excavation) and optimize the repair process parameters. At last, the low velocity impact damage specimens were repaired by patched thermo-reforming and nondestructive testing, and the repair effect was evaluated by residual strength test. The purpose of this project is to establish a set of analysis methods applicable to the repair and post-repair performance evaluation of thermoplastic composite materials with different low velocity impact damage degrees, laying a theoretical analysis foundation for the repair of thermoplastic composite materials.

热塑性复合材料具有优良的可修复特性，但目前针对冲击损伤的修理工艺仍存在修理区域应力集中以及修理工艺参数不规范等问题。基于不同低速冲击损伤特征确定最优修理方案，对热塑性复合材料结构修理维护和性能评价具有重要意义。本项目首先开展低速冲击试验分析铺层结构对机织热塑性复合材料CF/PPS冲击损伤特征的影响，量化冲击能量与不同铺层结构热塑性复合材料损伤修复区域的关系；然后对二次热压成型挖补修复后热塑性复合材料结构进行细观建模，分析修理区域的应力集中系数和修复界面剥离应力随修理工艺参数（挖补形状、挖补斜度）的变化规律并优化修理工艺参数；最后对损伤试件进行二次热压成型挖补修理并进行无损检测，采用剩余强度实验分析修理后结构失效形式，评价修理效果。本项目目的是建立一套适用于不同低速冲击损伤程度的热塑性复合材料修理及修复后性能评价的分析方法，为热塑性复合材料结构修理奠定理论分析基础。

热塑性复合材料具有优良的可修复特性，对于航空航天、轨道交通等领域含冲击损伤的热塑性复合材料结构具有重要意义。然而，热塑性复合材料损伤修复工艺仍存在修复区域应力集中、修复工艺参数不规范等问题。本项目通过试验与仿真方法相结合，阐明了不同冲击能量下热塑性复合材料的损伤机制及损伤范围，非冲击面的椭圆形损伤面积约为冲击面的损伤面积的1.72~1.75倍；基于多尺度、参数化修复试件仿真模型讨论了不同挖不同挖补斜度对于热塑性复合材料修复区域应力分布的影响规律：非冲击面修复半径越大，则修复区域应力集中系数越大；考虑二次热压修复工艺过程对修复区域界面性能的影响，基于热塑性树脂分子链浓度在非等温条件下的演化规律，发展了一种热力工艺历史下热塑性复合材料界面性能演化的预报模型，在优化修复结构参数及热压工艺参数的基础上，开展热塑性复合材料CF/PPS二次热压挖补修复，挖补构件的精准限位是保证修复构件尺寸及质量的关键因素。超声C扫结果显示挖补斜度越大则修复区域越容易存在孔隙，修复后CF/PPS试件弯曲强度和模量的恢复率最高可达90%，形成了含冲击损伤的热塑性复合材料修复流程及性能评价方法。项目相关研究成果可以应用于热塑性复合材料构件二次成型及结构修复相应领域。