Investigation of a crash concept for CFRP transport aircraft based on tension absorption

Abstract

Transport aircraft made of carbon fibre reinforced plastics (CFRP) have to provide an equivalent crashworthiness compared to today's aluminium aircraft designs. However, CFRP structures typically show brittle failure behaviour under complex loading conditions and little energy absorption, whereas aluminium structures provide comparably high energy absorption due to their ductile failure characteristics. Improved crashworthiness for CFRP fuselages can be obtained by the installation of special crash devices, which are designed for energy absorption by progressive failure in compression, tension or bending. The realisation of crashworthy CFRP fuselage designs with the focus on compression or bending absorbers is often associated with significant mass penalty compared to the purely static sizing of the corresponding fuselage structure. In this context, an alternative crash kinematics was developed and numerically investigated in which most of the kinetic energy is dissipated by tension absorption in the sub-cargo area of a fuselage structure. The numerical study was performed on the basis of a purely vertical impact with a two-bay fuselage section using the explicit finite element (FE) solver Abaqus/Explicit. The simulation results show for the developed crash kinematics several advantages, e.g. reduced mass penalty, with the tension absorption concept compared to crash concepts that use energy absorption by progressive crushing in the sub-cargo area.