Incline Firing Analysis Using ANSYS to Determine Directional Barrel Deformations

Abstract In this paper, the directional deformations of a 120mm smoothbore tank gun were analyzed during several initial firing angles. This analysis sets up the barrel as a cantilever beam and accelerates the projectile with a given pressure time load history. This study aims to understand the deformation patterns associated with various firing angles with a Finite Element Analysis (FEA) approach and seeks to obtain valuable initial conditions to improve long-range firing accuracy at a relatively large firing angle. The primary objective of the paper was to uncover a physical rationale behind the “rifle rule”, which suggests that when shooting at an inclined surface, the projectile tends to strike higher. The findings are intended to inform the development of a 3D trajectory analysis simulator. The axial, vertical, and horizontal deformation of the barrel at 0, ±15, ±30, and ±45 degrees are compared, as well as validating the results with the projectile’s exit velocity. Lastly, the results show that the vertical deformation of the barrel is significant enough to vary the trajectory of the projectile and should be considered during an inclined/declined firing scenario. While the axial and horizontal deformations are small enough to be considered trivial and unlikely to have a significant effect on the accuracy.