Normalization and Processing of Rotational Eddy Current Scans for Layup Characterization of CFRP Laminates

The verification of fiber orientation and layup in carbon fiber-reinforced polymer (CFRP) composite laminates is essential to guarantee the performance of the material. This work reports the background, methodology, and results of a rotational eddy current testing (ECT) system for determining fiber orientation and ply layup of unidirectional CFRP components. The system presented mechanically rotates a 15 MHz directional transmit-receive ECT probe, which poses several speed and consistency advantages. The paper presents a theoretical discussion of how these scans are produced, a unique preprocessing normalization method, and an optimization process for determining the layup from the captured datasets. Results show a high level of accuracy for identifying the unique directions present in a laminate, and the theory-supported model enables the extraction of layup order information of multilayer parts, even where repeated lamina are present within the laminate.

碳纤维增强聚合物（carbon fiber-reinforced polymer, CFRP）层压板的纤维取向与铺层验证，是保障材料综合性能的必要前提。本研究详述了一套用于检测单向CFRP构件纤维取向及铺层结构的旋转涡流检测（rotational eddy current testing, ECT）系统的研究背景、检测方法与实验结果。该系统通过机械驱动15 MHz定向收发式ECT探头旋转，在检测速度与一致性层面具备显著优势。本文从理论层面探讨了此类扫描的生成机制，提出了一种专属预处理归一化方法，并针对从采集数据集反推铺层结构的流程设计了优化方案。实验结果表明，该方案对识别层压板内存在的特征纤维取向具有极高精度；且基于理论支撑的模型可实现多层构件铺层顺序信息的提取，即便层压板内存在重复的单层铺层（lamina）时亦能有效完成。