A sensitivity analysis on Fibre bridging effects in delaminated composite panels under Flexural Loading Conditions

Fibre Bridging is one of the toughening mechanisms, arising in fibre-reinforced composite structures, which can play a relevant role in delaying delamination propagation under general loading conditions. In this paper, the influence of the Fibre Bridging phenomenon on the onset and propagation of delaminations in stiffened composite panels under three-point bending loading conditions have been numerically and experimentally studied. The investigated stiffened panels have been manufactured by using material systems, characterised by a different sensitivity to Fibre Bridging (low, medium, and high bridging sensitivity) and, then, tested under three point bending conditions. The experimental tests have been numerically simulated by means of a robust numerical procedure for the delamination growth simulation, implemented in the ANSYS® FEM code. Indeed the Ansys Parametric Design Language has been used to build a numerical FEM model able to take into account the influence of GIc variations related to the Fibre Bridging phenomenon as a function of the delamination length. The proposed numerical model has been preliminary validated by correlating numerical results and experimental data in terms of load and delaminated area as a function of the applied displacement. A final discussion has been proposed on the capability of the proposed numerical tool to simulate the influence of the material fiber bridging sensitivity on the flexure-induced delaminations onset and growth for the investigated stiffened panels.