基于激光热弹效应的碳纤维增强树脂复合材料缺陷检测机理研究北大核心CSCD

碳纤维增强树脂基复合材料(carbon fiber reinforced resin polymer, CFRP)在周期载荷作用下产生的基体裂纹、纤维断裂等微损伤的累积会严重影响CFRP的力学性能,微损伤尺寸较小且位置分散,传统的无损检测方法难以准确识别。激光超声检测技术具有非接触、检测速度快、测量范围广等优点,特别是结合激光的远距离激励和大角度入射的优势,在大尺寸、曲面形式结构材料的损伤检测方面有巨大的潜力。本文基于激光热弹效应,在分析激光作用到CFRP后的温度、应力和位移场分布的基础上,对CFRP内部超声波的产生过程和传播特性进行了系统研究。并通过对CFRP中不同处存在缺陷时的超声波回波信号的分析比较,得到缺陷位置与回波信号特性之间的对应关系,从而实现从回波信号特征反演出CFRP中缺陷位置的关键信息。

Study of defect detection mechanism of carbon fiber reinforced polymer based on laser the rmoelastic effect

The accumulation of micro-damage such as matrix crack and fiber fracture in car bon fiber reinforced polymer (CFRP) under cyclic loading will seriou sly affect the mechanical properties of CFRP.The size of micro-damage is small and the locati ons of micro-damage are scattered,which are difficult to be accurately identified by tr aditional nondestructive testing methods.Laser ultrasonic detection technology has the ad vantages of non-contact,fast detection speed,wide measurement range,et al.Especially combine d with the advantages of laser long distance excitation and large angle incidence,it has a great potential in the damage detection of large size and curved structure materials.Based on the thermoelastic effect of laser,the generation process and propagation characteristics of ultra sonic wave in CFRP are systematically studied on the basis of analyzing the distribution of te mperature,stress and displacement field after laser is applied to CFRP.Through the analysis and comparison of ultrasonic echo signals with defects in different places in CFRP,t he corresponding relationship between defect position and echo signal characteristics is obtained,so as to re alize the reverse performance of the key information of defect position in CFRP from the echo sign al characteristics.