Crashworthy evaluation of a 1/5-scale model composite fuselage concept

A 1/5-scale model composite fuselage concept for light aircraft and rotorcraft has been developed to satisfy structural and flight loads requirements and to satisfy design goals for improved crashworthiness. The 1/5-scale model fuselage consists of a relatively rigid upper section which forms the passenger cabin, a stiff structural floor, and an energy absorbing subfloor which is designed to limit impact forces during a crash event. The focus of the present paper is to describe the crashworthy evaluation of the fuselage concept through impact testing and finite element simulation using the nonlinear, explicit transient dynamic code, MSC/DYTRAN. The impact design requirement for the scale model fuselage is to achieve and maintain a 125-g floor-level acceleration for a 31 ft/s vertical impact onto a rigid surface. This impact requirement corresponds to a 25-g floor-level acceleration for a geometrically-similar full-scale fuselage section. 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 1/5-scale model fuselage section, which was dropped from a height of 15 feet to generate a 31 ft/s vertical impact velocity onto a rigid surface. The experimental data demonstrate that the fuselage section with a foam-filled subfloor configuration satisfied the impact design requirement. In addition, the fuselage section maintained excellent energy absorption behavior for a 31 ft/s vertical drop test with a 15°-roll impact attitude. Good correlation was obtained between the experimental data and analytical results for both impact conditions.