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.
Heat effects measurements in process of dynamic crash of polymer composites
In the work, the attempt to determine the influence of loading rate on temperature of the surface of the crushed composite energy absorbing elements was undertaken. The specimens made of epoxy composites reinforced with glass fabrics and carbon fabrics of the structures [(0/90)T ]n were subjected to dynamic investigations. Thermovision investigations were conducted during energy absorbing tests. A thermovision camera enables the measurement of the temperature on the whole surface of the specimen visible in the camera lens while the measurement with the use of thermocouple is only local and has great heat inertia. During the investigations, the increase of specimen temperature related to impact velocity occurs. The temperature increase is caused by friction between the particles of the crushed specimen and by friction between the specimen and the support of the strength machine. At high loading rates, the increase of temperature on the surface of the specimens was significantly greater than the softening temperature of the epoxy resin E-53.
Fiber-reinforced plastic composites for energy absorption purposes☆
Abstract The energy-absorbing characteristics in axial collapse of structures made from fiber-reinforced plastic (FRP) composites are reviewed from both the materials and the structural viewpoints. The type and nature of the fiber and resin, the geometry of the structure and the fiber arrangement affect significantly the energy-absorbing capability, but the data currently available are not yet sufficient to give a clearly unambiguous answer for a particular situation. An effective trigger mechanism is necessary to initiate stable collapse since thin-wall structures in particular are prone to unstable collapse. Methods are described to estimate the energy-absorbing potential of an FRP composite structure.