Electrospun ZnO-integrated Carbon Fiber-reinforced Polymer Laminates for Structural Health Monitoring: A Cross-correlation Time Difference of Arrival - based Impact Localization Approach
J. Environ. Nanotechnol., Volume 15, No 2 (June 2026) pp. 530-543
Abstract
Structural health monitoring (SHM) of composite laminates typically relies on externally attached or embedded sensors, which may adversely affect structural integrity and long-term durability. To address this limitation, the present study develops a ZnO-based self-sensing Carbon Fiber Reinforced Polymer (CFRP) laminate capable of accurate impact localization using a cross-correlation-based Time Difference of Arrival (TDoA) method. Electrospun ZnO nanofibers were embedded within the laminate structure and systematically compared with conventional ZnO thin-film sensors. The sensing system consists of three spatially distributed sensors operating at a sampling frequency of 1 MHz. The guided wave velocity was experimentally determined as 1026 m/s using a pitch-catch technique. The acquired piezoelectric signals were preprocessed through detrending and Savitzky–Golay filtering to remove baseline drift and high-frequency noise. Cross-correlation analysis was then employed to extract inter-sensor delays, yielding time differences of 0 µs and 2 µs, corresponding to distance differences of 0 m and 0.00205 m, respectively. These parameters were subsequently utilized in a triangulation algorithm to estimate the impact coordinates. The proposed localization framework demonstrated high accuracy across multiple test points, with absolute errors ranging from 0.50 cm to 1.33 cm. For example, an impact at (15, 8) cm was predicted as (13.98, 7.15) cm, resulting in a deviation of 1.33 cm. Similarly, lower errors of approximately 0.50–0.94 cm were consistently observed across other test cases, indicating robust localization performance. ZnO thin-film sensors exhibited slightly higher signal amplitude and improved localization precision due to direct electrode coupling. However, ZnO nanofiber-integrated laminates achieved comparable accuracy while significantly enhancing structural compatibility, reducing interfacial discontinuities, and improving damage tolerance. The results confirm that the integration of ZnO-based sensing layers with cross-correlation TDoA analysis provides a reliable, accurate, and structurally efficient approach for impact localization in composite structures. This method offers strong potential for next-generation lightweight SHM systems in aerospace, automotive, and high-performance engineering applications.
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