Compressive Behaviour of a Damaged Omega Stiffened Panel: Damage Detection and Numerical Analysis

The damage detection of composite material structures is one of the major concerns in aerospace due to the complexity of composites’ failure mechanisms, their onset location and propagation paths. The failure of an omega stiffened CFRP panel for aerospace applications subject to compressive load is experimentally and numerically studied in this work. The specimen is characterised by a large notch damage located in the middle of the bay and oriented according to the load direction. A compressive mechanical test has been performed to determine the global buckling phenomenon and the induced progressive fibre-matrix damage and delamination development. The panel has been instrumented with back-to-back strain gauges in skin and stringers locations. Non-destructive techniques, such as lock-in thermography and ultrasounds, have been used to detect the damage status and the cracks size and depth after failure. Numerical analysis, aimed to investigate the failure mechanisms and their interaction during compression, has been carried out by means of the FE software ABAQUS and the results have been compared to the experimental data. The combined assessment of numerical results and experimental data has allowed to provide a detailed insight of the investigated phenomenon.