The structural integrity of a novel composite adhesively bonded flap-track beam

The structural integrity of a flap-track beam (FTB) made from non-crimp fabric composites and assembled using mechanical fasteners and adhesively bonded joints is investigated using full-scale experiments and numerical modeling. The FTB, being an aircraft structural component, has been selected as the verification structure and demonstrator of a novel material-driven design concept aiming to progressively replace mechanical fasteners by adhesively bonded joints and introduce fabric composites of enhanced through-thickness properties in aero-structures. For the sake of investigation, the FTB has been subjected to a combination of static and fatigue loading conditions taken from realistic load-scenarios. Due to size and complexity of the structure and testing demands, a special test-rig was developed for the occasion. During loading, the response of the structure has being fully monitored using a network of sensors along with an optical measurement system. After loading, the health of the structure was monitored using non-destructive inspection. Complementary to mechanical testing, a 3D detailed FE model was developed for virtual experimenting. On the basis of the model, progressive damage modeling has been implemented to simulate initiation and progression of composite failure as well as debonding. Both experiments and model have shown that the composite FTB is capable to effectively carry the load which the original fastened metallic FTB has been designed to carry. Localized damage that has no significant effect on the integrity of the structure has been detected at fastener areas and bonded joints containing initial defects. Between experiments and model a satisfactory agreement has been achieved considering the uncertainties in experimental procedure and numerical errors of the model.