A Crashworthiness Test for Composite Fuselage Structure

Abstract

Composite materials are being considered for application to primary fuselage structure. It is improtant that the crash energy absorption capacity of the composite structure be as good as that of the aluminum construction. This complex response is difficult to evaluate analytically and expensive to determine experimentally. This paper represents an attempt to develop an inexpensive test method which permits the ranking or quantitative evaluation of different material/structural concepts with regard to their energy absorption capacity. The test specimen consists of a cylindrical shell 9 inches in diameter and 18 inches in length. Some of the cylinders are hat stiffened. Some are of honeycomb sandwich construction. The materials are aluminum, graphite, fiberglass, and Kevlar 49. The specimens all have the same design requirements, which do not include energy absorp- tion. The cylinders are axially crushed and their load/deflection curves obtained. The areas under these curves are the energies dissipated or absorbed during crushing. The stiffened composite specimens all absorbed less energy than the aluminum specimens. Stiffened and sandwich aluminum designs were comparable. The sandwich composite specimens performed much better than the stiffened ones but still failed to match the performance of aluminum. It appears that additional energy absorption will have to be designed into composite fuselages to match the characteristics of aluminum fuselages.