Relationship between mechanical-property and energy-absorption trends for composite tubes
U.S. Army helicopters are designed to dissipate prescribed levels of crash impact kinetic energy without compromising the integrity of the fuselage. Because of the complexity of the energy-absorption process it is imperative for designers of energy-absorbing structures to develop an in-depth understanding of how and why composite structures absorb energy. A description of the crushing modes and mechanisms of energy absorption for composite tubes and beams is presented. Three primary crushing modes of composite structures including transverse shearing, lamina bending, and local buckling are described. The experimental data presented show that fiber and matrix mechanical properties and laminate stiffness and strength mechanical properties cannot reliably predict the energy-absorption response of composite tubes.
The Crush Performance of Composite Structures
Compression tests have been carried out on a range of composite structures made from a csm/polyester laminate. Geometries tested included truncated cones, slotted and sectioned round tubes, square tubes and flat plates. For cones and tubular specimens failure is by progressive crush absorbing relatively large amounts of energy. A trigger is necessary to initiate crush in tubular specimens, however cone failure is self triggering with crush commencing at the small end. Plate specimens failed by catastrophic splitting and buckling with minimal energy absorption. The inability of plate specimens to support stable crush is thought to be due to the lack of transverse restraining forces in the crush zone.
Collaborative Aircraft Design Methodology using ADAS linked to CEASIOM
The aircraft design stages, conceptual and preliminary, are necessarily collaborative bytheir very nature. An example design carried out in this paper brings the collaborativeaspects of design to l ...