The basic premise for developing a projectile-gun interaction model is to be able to provide an analytical tool for examining problems which may arise in the development of new and in some cases existing armament.
Two separate computer programs have been developed in the initial phase of the model formulation. One of the programs is a six degree-of-freedom dynamics model of a projectile balloting of finite geometry and inertia traveling in a flexible, rifled or smoothbore gun tube. This model accommodates projectile spin, mass eccentricity, projectile/bore interfacial friction, elastic deformation of the projectile rotating band, and balloting including bourrelet impact and rebound with the bore. The other is a FEM(Finite Element Method) model of gun-tube 3-dimensional motion and vibration. This model accommodates gun tube flexibility and boundary condition.
The two are coupled to provide the ability to assess the mutual effects of projectile/gun-tube interaction. So, it is possible to determine the combined effects of gun-tube motion and vibration upon projectile balloting, and conversely, the effects of balloting upon the gun dynamics.
The essential variables to be obtained from this simultaneous analysis are the initial transverse displacement/velocity, pitch, yaw, pitch rate, and yaw rate of the projectile after it exits the muzzle. These initial values can then be combined with already existing exterior ballistics program to provide gun performance parameters such as accuracy and dispersion of the shot down range.