Abstract:
This paper describes the development of a finite element model for a 40 mm Case Telescoped Ammunition and its associated gun, designed to simulate the in-bore travel of the projectile during firing. The model is intended for parametric studies to examine the influence of ammunition and gun parameters on the projectile's exit conditions. The work is part of a PhD thesis focused on the accuracy of Kinetic Energy Rounds.
The model is built on principles used for a 120 mm gun system but addresses unique challenges of the 40 mm system, such as progressive rifling and a slipping obturator. The simulation accounts for complex interactions, including barrel wall loading from high-pressure propellant gases. The paper notes that a full fluid-structure interaction (FSI) simulation, including the propellant gases, was too complicated, so a "weak coupling" method was used, where pre-calculated pressure curves were applied as a load.
A key requirement for the model was simulating the recoil system, which is powered by springs in the 40 mm gun, unlike the 120 mm system which uses a hydraulic principle. The model's results were validated against strains measured on the gun barrel and an instrumented penetrator with an on-board data recorder. Various configurations were tested to match experimental data, highlighting the importance of accurate contact logic and friction coefficients.
