DYNAMIC-RESPONSES OF A KINETIC-ENERGY PROJECTILE UNDER TRANSVERSE LOADINGS

We report on the effects of launch tube nonstraightness and asymmetric loading on the accuracy performance of a kinetic energy projectile. M odeling the projectile as a rigid body within the launch tube, we obta in and solve the equations of rotary motion to calculate the orientati on of the projectile relative to the tube as a function of time. Three launch tube geometries are modeled; curiously, the most severe enviro nment does not produce the most deviant projectile orientations during in-bore travel or at muzzle exit. To determine the effects of asymmet ric loading, we model the rod as a nonuniform two-dimensional beam, su bject to a transverse blast load. Determined experimentally, the sabot equivalent stiffness is bounded between 10(6) and 10(7) N/m. These bo unds are used in an elastic boundary condition to the rod finite eleme nt model. The ANSYS transient Vibration analyses predict a peak transv erse displacement of 20 mm and a peak transverse velocity of 75 mm/s a t muzzle exit. We conclude that: (1) base pressures asymmetry induces transverse vibrations in the projectile, and these vibrations are affe cted by sabot stiffness; and (2) launch tube profile nonstraightness i nduces rigid body rotations in the projectile, and these rotations may or may not increase with launch tube severity.