Dynamic thermal models for simulation of Lock-in Thermography tests on debonded composite T-joint

Debonding is a critical failure mode in composite T-joint structures compromising structural integrity and performance. This study presents a novel approach to simulating Lock-in Thermography (LT) tests with an accurate representation of heat flux and convective boundary conditions aiming to speed up experimental LT analyses for debonding detection. The numerical model based on the Carrera Unified Formulation (CUF) implemented using the MUL2 software represents the debonded region as an air gap with variable thickness. Phase contrast maps from simulations were compared with experimental results to evaluate model accuracy and determine the air-gap thickness corresponding to actual debonding. A parametric study examined how variations in air-gap thickness affect phase contrast identifying configurations that closely match experimental observations. Results demonstrate that CUF-based modeling effectively predicts phase contrast variations associated with debonding providing a reliable tool for Non-Destructive Testing (NDT) of composite structures. Compared to conventional commercial FE software the CUF approach significantly reduces computational time by using fewer degrees of freedom while maintaining high fidelity making it an efficient tool for fast parametric studies and improved structural health monitoring.