Development of a scale model composite fuselage concept for improved crashworthiness

A composite fuselage concept for light aircraft has been developed to provide improved crashworthiness. The fuselage consists of a relatively rigid upper section, or passenger cabin, including a stiff structural floor and a frangible lower section that encloses the crash energy management structure. The crashworthy performance of the fuselage concept was evaluated through impact testing of a one-fifth-scale model fuselage section. The impact design requirement for the scale model fuselage is to achieve a 125-g average poor-level acceleration for a 31-ft/s vertical impact onto a rigid surface. The energy absorption behavior of two different subfloor configurations was determined through quasi-static crushing tests. For the dynamic evaluation, each subfloor configuration was incorporated into a one-fifth-scale model fuselage section, which was dropped from a height of 15 ft to achieve a 31-ft/s vertical velocity at impact. The experimental data demonstrate that the fuselage section with a foam-block subfloor configuration satisfied the impact design requirement. A second drop test was performed to evaluate the energy absorption performance of the fuselage concept for an off-axis impact condition. The experimental data are correlated with analytical predictions from a finite element model developed using the nonlinear, explicit transient dynamic code MSC/DYTRAN.