FBG-UGW multi-source fusion for acoustoelastic compensation: enabling deformation–damage signal decoupling in CFRP structural health monitoring

Abstract Deformation of carbon fiber reinforced polymer (CFRP) structures under service loads induces significant ultrasonic guided wave (UGW) signal baseline shifts due to the acoustoelastic effect, causing deformation–damage signal coupling and resulting in false alarms or missed detections. To address this, we propose a novel Kriging-based strain field fusion and acoustoelastic compensation (KSFF-AC) algorithm. It integrates distributed strain data from a fiber Bragg grating (FBG) network to construct a physics-driven decoupling model that links strain to UGW variations. Kriging interpolation first reconstructs the full-field strain, enabling the calculation of path-weighted integrated strain for UGW paths. This strain is then input into an acoustoelastic linear model to reconstruct the UGW baselines in real-time. Bidirectional gradient loading and damage experiments validate the method: KSFF-AC reduces the reconstruction error from >13% to