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编织结构碳纤维复合材料电导率分布特性及电磁检测方法
【作者】 李硕；
【导师】 张荣华；
【作者基本信息】 天津工业大学 ， 控制科学与工程， 2021， 硕士
【摘要】 碳纤维增强复合材料(Carbon Fiber Reinforced Plastics,CFRP)具有耐高温、耐腐蚀、质量轻、强度高等优异的特性,被广泛应用在航空航天、风电叶片、汽车和压力容器制造等领域。然而在制作和使用过程中,由于碳纤维复合材料的工艺参数难以精确控制,且受到疲劳载荷、外力等因素的影响容易出现裂纹或者纤维断裂等损伤,存在很大的安全隐患。而电磁检测技术具有无接触、无辐射、成本低的优势,所以利用电磁检测技术研究碳纤维复合材料结构特性以及实现对其损伤监测,对提高生产效率,保证生产生活中的安全性具有十分重要的意义。本文研究对象为编织结构CFRP,编织结构CFRP包括二维编织和三维编织。首先基于碳纤维复合材料各向异性和异质性的特点,建立了二维平纹编织CFRP的方块模型和纱线模型。根据电磁感应原理设计了12线圈电磁式圆形阵列传感器,放置于模型上方得到传感器线圈的阻抗值。然后以无缺陷时的传感器电阻值为基础,在CFRP板上设置裂纹缺陷进行电磁仿真和实验,得到有缺陷时比无缺陷时传感器电阻更小的变化规律,利用传感器电阻变化特点获得了CFRP的裂纹损伤信息。三维编织结构比二维编织结构力学性能更加优良,之后本文对三维平纹和斜纹编织结构碳纤维复合材料的准静态三点弯曲损伤进行了研究。首先推导出了载荷-电导率理论模型,得到载荷和电导率变化关系。然后根据三维平纹和斜纹编织的结构进行力学和电学的仿真与实验,由于试验材料的宽度限制,传感器采用尺寸更小的双线圈传感器,得到载荷和传感器线圈电压的关系。结果表明:电涡流无损检测技术能够很好地表征编织结构的碳纤维复合材料电导率分布特性以及裂纹缺陷和抗弯曲性能。
【Abstract】 Carbon Fiber Reinforced Plastics(CFRP)has excellent characteristics such as high temperature resistance,corrosion resistance,light weight and high strength.It is widely used in aerospace,wind turbine blades,automobiles,and pressure vessel manufacturing.However,CFRP are prone to cracks or fiber breakage due to the difficulty of precise control of process parameters and the influence of factors such as fatigue load and external force during the production and use process,which poses great safety risks.While the electromagnetic eddy current nondestructive testing technology has the advantages of non-contact,non-radiation and low cost.Therefore,the use of electromagnetic detection technology to study the structural characteristics of CFRP and realize their damage monitoring is of great significance for improving production efficiency and ensuring safety in production and life.The research object of this paper is woven structure CFRP,which is divided into2-D and 3-D.First,based on the anisotropy and heterogeneity of carbon fiber composite materials,two models of block model and yarn model are established for 2-D plain weave CFRP.According to the principle of electromagnetic induction,a 12-coil electromagnetic circular array sensor is designed,placed above the model to obtain the impedance value of the sensor coil.Then based on the sensor resistance value when there is no defect,the crack defect is set on the CFRP board for electromagnetic simulation and experiment,the sensor resistance is smaller when there is a defect than when there is no defect.With this change rule,the CFRP crack damage information is obtained by using the characteristics of the sensor resistance change.The 3-D braided structure has better mechanical properties than the 2-D braided structure.After that,the quasi-static three-point bending damage of carbon fiber composites with 3-D plain and twill weave structure is studied.First,the loadconductivity theory model is derived,and the relationship between load and conductivity changes is obtained.Then according to the 3-D plain and twill weave structure,mechanical and electrical simulations and experiments are carried out.Due to the limitation of the width of the test material,the sensor adopts a smaller doublecoil sensor to obtain the relationship between the load and the sensor coil voltage.The results show that the eddy current non-destructive testing technology can well characterize the electrical conductivity distribution characteristics,crack defects and bending resistance of carbon fiber composites with woven structures.