Mechanical engineer, U.S. Army Materials Technology Laboratory, Watertown, MA
The investigation is concerned with the control of force transmitted to the support caused by central normal impact of a projectile on a plate supported by composite isolators with constrained rattle space. Normally isotropic isolators with appropriate low stiffness will absorb appreciable amount of impact energy. But this requires some space (rattle space) for deflection when the plate is subjected to projectile impact. In certain applications (such as plates used as armor in combat aircraft) there is not enough space for the plate to move normal to the plane of the plate. In the present analysis, by using composite isolators the plate is allowed to rotate in the plane of the plate so that less space (rattle space) is required normal to the plane of the plate. By allowing the plate to rotate in its plane, the impact energy is absorbed in the rotational direction in addition to the usual normal to the plane of the plate; thereby transmitting less force to the support compared to the case with isotropic isolators. A method of controlling the force transmitted to the support is to control the natural frequency of the system. In the present analysis the influence of fiber orientation and material properties on the natural frequency of the plate and composite support system is shown.
Paper ID: CTR10140J