Delamination and Skin-Spar Debond Detection in Composite Structures Using the Inverse Finite Element Method

This work presents a novel strategy for detecting and localizing intra- or inter-laminar damages in composite structures using surface-instrumented strain sensors. It is based on the real-time reconstruction of structural displacements using the inverse Finite Element Method (iFEM). The iFEM reconstructed displacements or strains are post-processed or 'smoothed' to establish a real-time healthy structural baseline. As damage diagnosis is based on comparing damaged and healthy data obtained using the iFEM, no prior data or information regarding the healthy state of the structure is required. The approach is applied numerically on two carbon fiber-reinforced epoxy composite structures: for delamination detection in a thin plate, and skin-spar debond detection in a wing box. The influence of measurement noise and sensor locations on damage detection is also investigated. The results demonstrate that the proposed approach is reliable and robust but requires strain sensors proximal to the damage site to ensure accurate predictions.

Automated summary

This work presents a novel strategy that uses surface-instrumented strain sensors for detecting and localizing damages in composite structures. The strategy relies on real-time reconstruction of structural displacements using the inverse Finite Element Method (iFEM). The iFEM reconstructed displacements or strains are processed to establish a real-time healthy structural baseline, making prior information unnecessary. The approach is demonstrated on carbon fiber-reinforced epoxy composite structures, showing reliability and robustness but highlighting the importance of sensor proximity to accurately predict damages.