Non-Destructive Inspection (NDI) of Large Scale Composite Structures

ISE is currently developing a robust computational method for the determination of structural defects within laminated composite aerospace structures. The current method under development uses a mathematically derived specially-orthotropic lamination model subjected to sensitivity perturbations from empirical dynamic transfer-function data. Predicted failure areas, precipitated by the loss of signal coherence between test points, are screened under a statistical failure model using the maximum strain energy (Beltrami) theory and maximum distortion energy (von Mises) theory as indicators of areas of delamination of plies, disbonding of joints, or void detection.

The proposed method would open the door for a rapid, yet computationally elegant way to access potential composite structural defects in aircraft wing and fuselage sections as well as helicopter rotor systems, saving downtime costs while maintaining airworthiness. 

The photo to the right shows one of the many tests being performed to quantify the extent of disbonding and delamination within an eight-ply woven composite panel specimen having a NASA ply configuration of [0/45/0/-45]_S and an EA-956 resin. Several specimens with known defects (similar to the one shown) are being tested to determine the accuracy of the model as a predictive tool for composite failure analysis.