基于涡流场相轨迹的碳纤维多层立体编织在线质量评估方法

Carbon fiber multilayer stereo woven material overcomes the weak mechanical properties between the layers of the traditional multilayer laminated carbon fiber composite material so that it becomes the forefront of high-performance composite material preparation industry. However, carbon fiber multilayer stereo woven material is easy to produce structural defects in the production process. The off-line defect detection is carried out after products curing in the traditional solution, which prevents us recycling of defected defecting products. High defective rate is the main bottleneck to hinder the large-scale industrialization of carbon fiber multilayer stereo weaving materials. Thanks to the advantages of non-contact, no radiation, low power consumption and so on the eddy current nondestructive testing method is very suitable for online quality detection. In view of the facts above, this research studies the online quality detection method of carbon fiber stereo woven process based on the phase analysis method. The research content mainly includes: The method of forward problem model of carbon fiber multilayer stereo woven materials; Eddy current nondestructive testing theory based on phase trajectory method; Fast multi frequency phase-sensitive demodulation method based on parallel computing method. The research results can realize on-line quality evaluation of carbon fiber multilayer three-dimensional braiding process. What’s more, the defective products can be detected and repaired in time before curing, which is beneficial to reduce the rate of defective products and to accelerate the large-scale industrialization process of such materials.

碳纤维多层立体编织材料克服了传统层合碳纤维复合材料层间力学特性薄弱的缺点，逐步成为高性能复合材料制备产业的前沿发展方向。然而，碳纤维多层立体编织材料在生产过程中极易产生结构缺陷。传统的检测方法为固化成型后的离线缺陷检测，被检出的次品无法回收利用。高次品率是阻碍碳纤维多层立体编织材料大规模产业化的主要瓶颈。电磁涡流无损检测方法因其具有非接触、无辐射、低功耗等优点，非常适合进行在线质量检测。本项目基于此背景，探索基于相位分析理论的碳纤维立体编织过程在线质量检测方法，研究内容主要包括：碳纤维多层立体编织材料正问题模型研究；基于相轨迹方法的电涡流无损检测方法研究；基于并行计算方法的快速多频相敏解调方法研究。研究成果可实现对碳纤维多层立体编织过程的在线质量评估，在固化成型前及时检测出产品缺陷并进行修补，降低产品次品率，加快此类材料大规模产业化的进程。

碳纤维增强复合材料(Carbon Fiber Reinforce Polymer, CFRP)作为一种新型材料具有耐高温、强度高、化学稳定性强、抗蠕变等一系列特点，在多个工业领域大量应用，针对这种新型材料的无损检测方法的研究也越来越受到关注。利用无损检测技术发现在其制造和使用过程中的各种缺陷，对保证生产生活中的安全性和促进碳纤维复合材料的发展，具有十分重要的作用。涡流检测是一种非接触、低成本、无辐射、不需要耦合剂的检测技术，它是基于载流线圈与导电材料之间的电磁感应原理实验的。本项目根据纤维复合材料的检测需求，针对实际使用中对更加常见的编织CFRP，对其电测涡流检测技术进行了深入了研究。在深入研究单向CFRP的电学特性和涡流通路的基础上，首先提出了一种编织CFRP的离散化电导率模型，使用双圆旋转线圈传感器，以传感器阻抗信号作为检测信号特征量对平纹编织CFRP进行有限元仿真分析。在此基础上，设计了编织CFRP的检测系统，对编织CFRP的缺陷以及疲劳进行了分析总结。研究表明，线圈阻抗的最大变化出现在经纱和纬纱的电导率矢量叠加的最大值处，且仿真结果与实验结果误差小于0.6％，故本文所提出的模型可以有效模拟平纹编织CFRP的电磁特性，同时可以有效地检测出编织CFRP的缺陷以及疲劳情况，具有较好的可视化。编织CFRP的电导率在循环载荷作用下会发生变化。此外，可以通过在块均质化模型中改变电导率来模拟编织CFRP的疲劳现象。