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

Area of Science:

• Structural Health Monitoring
• Composite Materials Science
• Computational Mechanics

Background:

• Composite structures are susceptible to intra- and inter-laminar damage.
• Accurate damage detection is crucial for structural integrity and safety.
• Existing methods may require baseline data of the healthy state.

Purpose of the Study:

• To present a novel strategy for detecting and localizing intra- or inter-laminar damages in composite structures.
• To develop a damage diagnosis approach that does not require prior information of the healthy structure.
• To evaluate the proposed method's reliability and robustness under various conditions.

Main Methods:

• Utilizing surface-instrumented strain sensors for data acquisition.
• Employing the inverse Finite Element Method (iFEM) for real-time reconstruction of structural displacements.
• Post-processing (smoothing) of iFEM results to establish a real-time healthy structural baseline.
• Comparing damaged and healthy structural data for damage diagnosis.

Main Results:

• The proposed approach successfully detected and localized delamination in a thin plate and skin-spar debonding in a wing box numerically.
• The method demonstrated reliability and robustness in damage detection.
• The accuracy of damage prediction is influenced by measurement noise and sensor proximity to the damage site.

Conclusions:

• The developed strategy offers a reliable and robust method for composite damage detection and localization.
• The inverse Finite Element Method (iFEM) is effective for real-time structural displacement reconstruction and baseline establishment.
• Optimal sensor placement proximal to potential damage sites is critical for accurate predictions.