Influence of the gun barrel straightness on projectile exit conditions

22 ème Congrès Français de Mécanique.Gun accuracy is influenced by several parameters during the internal ballistics phase. Accuracy is defined by the bias and dispersion of impact points on the target. The aim of this study is to determine the influence of gun barrel straightness on projectile exit conditions, in order to understand how to improve weapon accuracy. A numerical firing analysis was carried out with LS-Dyna software. The model validity is proven by its ability to accurately predict the measured circumferential strains caused by the forcing effect of the projectile, and by the consistency of the contact forces at the projectile-tube interface. To validate the firing simulation, circumferential strains of the tube were measured and compared to LS-Dyna results. Subsequently, the barrel geometry was modified to add a straightness defect to the initial curvature due to gravity. Lastly, a post-treatment was performed to determine the angular and transverse velocities of the projectile during internal ballistics phase.This analysis shown the influence of specific shapes on ammunition balloting and velocity.