Optimization of Finite Element Modeling Methodology for Projectile Models

Abstract

Gun-fired projectiles are subjected to severe loads over extremely short duration. There is a need to better understand the effects of these loads on components within a projectile. While experimental data can be helpful in understanding projectile launch phenomena, collecting such data is usually difficult. There are also limitations on the reliability of sensors under these circumstances. Finite element modeling (FEM) can be used to model the projectile launch event. Currently, engineers usually use large number of elements to accurately model the projectile launch event, which results in an extremely long computational time. FEM results in these cases are always subject to questions regarding accuracy of the results and proof of mesh stability This paper presents an expert system that can reduce computational time needed to perform FEM of gun-fired projectiles. The proposed approach can result in reducing computational time while ensuring that accuracy of results is not affected. Recommendations of the expert system are reached through two stages. In the first stage, an equivalent projectile with simple geometry is created to reduce the complexity of the model. In the second stage, parameters controlling mesh density of the equivalent projectile are used as variables in an optimization scheme with the objective of reducing computational time. Accuracy of the acceleration results from an optimized model with respect to a model with an extremely fine mesh is used as an inequality constraint within the optimization search. A projectile model meshed with aspect ratios obtained from the optimization search produces good agreement with the finite element results of the original densely-meshed projectile model while significantly reducing computational time. It is anticipated that this approach can make it easier to conduct parametric analysis or optimization studies for projectile design.