Dynamic Behavior of Advanced Gun Barrels inResponse to Launch of a Projectile

摘要

Since the invention of guns and projectiles, the objective for ballisticians is torndeliver more mass at a higher velocity for a further distance. As projectile velocityrnincreases and approaches to a critical value, referred as the critical velocity in thernconventional gun community, resonance may occur and result in a very high amplitudernstresses and strains at the instant and location near the armature of projectile. Therndynamic response is particularly crucial if a gun barrel is designed to be lightweightrnbarrels for hypervelocity launch of projectile. Stress and strain profiles in the rail gunrnunder a dynamic condition are quite different and generally cannot be determined from arnstatic analysis. An analytical model is developed to study the dynamic behavior ofrnadvanced gun systems such as composite gun barrel with conventional propulsion andrnelectromagnetic (EM) rail gun in response to high-speed projectile movement.rnFor a composite gun barrel, both analytical and numerical solutions are developedrnto model the dynamic response of the barrel. Cylindrical shell theory is extended tornderive a closed-form expression of critical velocity for an anisotropic gun barrel. Therngoverning equation of EM rail gun under dynamic condition is derived based on arnstructural model of a beam on elastic foundation. The rail is modeled as a beam while therncontainment is an elastic foundation. The critical velocity of a gun with a geneticrnconfiguration is illustrated as a function of material properties, geometry, and barrelrnconstruction. A parametric study is performed based on an assumed gun section andrnconstruction. The results provide a good understanding to design a rail gun subjected torndynamic loading conditions.