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

Abstract

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.

Delamination Detection and Localization in Vibrating Composite Plates and Shells Using the Inverse Finite Element Method

“…Moreover, vibrational modes will become more complex as the dimensions of the domain increase, whereas the iFEM-RZT-based method is very versatile in terms of numerical/practical implementation thanks to its well-developed library of inverse elements [33,44,47,50]. Finally, the most recent iFEM-based delamination detection technique [56] is more economical than the present methodology in terms of instrumentation; however, it lacks the capability to detect the delaminated region through the thickness of the laminate, whereas the technique proposed in the present paper is exempt from such a restriction. layer-wise damage identifiers can be calculated at the delaminated region.…”

“…The findings of this research effort were further consolidated by validating the novel methodology against the experimental test data. Most recently, Roy and Gherlone [ 56 ] targeted delamination damage detection in composite structure. In their study, the unidirectional strain data acquired from the composite material were smoothed over the entire problem domain, which were then used to locate delamination damage.…”