Thermo-mechanical behaviour of a composite stiffened panel undergoing the tail-pipe fire event

In this paper, a numerical/experimental study is introduced on a carbon fibre reinforced polymer composite panel experiencing the tail-pipe fire phenomenon. This phenomenon, being of main concern for an Airplane during the engine-starting phase, can be qualitatively described as the ignition of a flame outside the nozzle impacting the adjacent aircraft structural components, such as the wing or the tail. The tail-pipe fire phenomenon is characterized by a variable duration and may cause the overheating or even the damage of the aircraft components. A numerical model, able to simulate the thermomechanical behaviour of composite structures under fire, is proposed. The presented approach, considering a strong coupling between the thermal and the structural fields and taking into account thermal and mechanical properties degradation, has been implemented in the commercial FEM software ABAQUS and applied to a stiffened composite panel. The numerical model has been validated by comparing the ABAQUS numerical results to the experimental data obtained by an ad-hoc campaign including mechanical tests under variable thermal conditions. The comparisons, performed in terms of Temperature-Time and Load-Strain evolution histories, showed a good agreement between numerical and experimental data, confirming the robustness of the proposed numerical tool and its effectiveness in predicting damage onset and propagation due to the presence of high thermal gradients.