The Development of a Floor Former Concept Incorporating Energy-Absorbing Composite Tubes

The structures technology group at Boeing Rotorcraft – Philadelphia has been developing and testing concepts for an energy-absorbing composite floor former that enables the use of under-floor fuel storage for transport rotorcraft. Objectives were to develop beam concepts that endure the flight loads of a hypothetical rotorcraft and maximize the energy absorption during a 42 ft/sec crash event. A concept that incorporates energy-absorbing tubes was selected, designed, fabricated, and tested. Crush data is presented for single energy-absorbing tubes in round and hexagonal configurations, the results of which show that round tubes absorb more specific energy. Detailed discussions of the design, tooling, and fabrication of a concept structure incorporating the tubes follow. Testing revealed that interactions between the tube containing structure and the tubes themselves inhibits the tubes from attaining maximum energy absorption levels achieved during unit testing. Further studies and designs are planned to understand and resolve the phenomena.