SOME RESULTS FROM A CRASH ENERGY ABSORPTION TEST FOR EVALUATING COMPOSITE FUSELAGE CONSTRUCTION

Composite cylindrical shell specimens have been crushed in compression as a means of observing and measuring their energy absorption characteristics. These tests have provided a practical basis for comparing various composite construction concepts to aluminum. However, in full scale helicopter drop tests it can be seen that a part of the vehicle kinetic energy is absorbed in skin shear. Therefore, to compare the shear and compression behavior, a duplicate set of cylindrical specimens were tested in torsion. These tests compared aluminum, fiberglass, Kevlar, and graphite in the form of sandwich and stiffened skin construction. The energy absorption characteristics differed between shear and compression and the results were more complex. However, some of the conclusions from the compression tests remained valid. Namely, sandwich construction absorbed more energy than stiffened skin construction. Aluminum and Kevlar/aluminum hybrid had the highest energy absorption capacity of the stiffened skin specimens. Also, Kevlar and aluminum stiffened skins had superior skin tearing resistance.