Crash analysis of composite aircraft fuselage under belly landing [EMBARGOED]

Abstract

In the aviation industry, accidents during landing are more frequent compared to other phases of flight and in most of the cases the aircraft is forced to make an emergency belly landing when the landing gear malfunctions. This study aims to analyze the energy absorption of a typical composite aircraft fuselage section under such crash belly landing. The impact test of the composite fuselage section simulations was created and analyzed using LS-Dyna finite element software. As the energy absorbed by the fuselage elements depends on various parameters of the composites, a detailed parametric study has been carried out. The effect of different composite materials with different layup of the skin of the fuselage on the energy absorption is studied in detail. Moreover, the study also analyzed the impact of various external factors, including landing terrain and skin thickness, on energy absorption. The analysis comprised landing scenarios on rigid ground, water surface and soft soil, with different impact velocities. The aim was to assess how these factors influenced the energy-absorbing capacity. Five different materials that are commonly used in aerospace applications are selected in this study such as aluminium, carbon fiber reinforced polymer (CFRP) glass/epoxy, graphite/epoxy, Kevlar/epoxy and boron/epoxy. Frames and skin were found to have the highest energy absorption contribution across all cases, while passenger floor and struts had the lowest contribution. Moreover, it was found that fuselage skin made of glass/epoxy absorbed higher energy compared to other materials. Other than that, the energy absorbed by the skin during an impact was highest when composite layups were made of unidirectional laminates. Regarding the effect of different skin thickness on energy absorption, it is found that as the thickness increases, energy absorbed decreases. As for the effect of different terrain, results demonstrated that the fuselage absorbs the most energy when it hits rigid ground compared to soft soil and water surface. Apart from that, it was demonstrated that the fuselage absorbs higher energy when two components of velocity are applied as compared to one component of velocity. Additionally, the energy absorbed by the fuselage is less when it hits the ground with an angle of inclination than when it hits the ground flat. Important conclusions on the effect of belly-landing impact on the onboard passengers are also derived based on various case studies.