Finite-element simulations and probabilistic fracture assessments of the response of alternate rifling geometries

A 3-D finite-element model was used to simulate the severe and localized thermal/pressure transients and the resulting stresses experienced by a rifled ceramic-barrel with a steel outer-liner; the focus of the simulations was on the influence of non-traditional rifling geometries on the thermoelastic- and pressure-stresses generated during a single firing event. In order to minimize computational requirements, a twisted segment of the barrel length based on rotational symmetry was used. Using this simplification, the model utilized uniform heating and pressure across the ID surface via a time-dependent convective coefficient and pressure generated by the propellant gasses. Results indicated that the unique rifling geometries had only a limited influence on the maximum circumferential (hoop) stresses and temperatures when compared with more traditional rifling configurations because of the compressive thermal stresses developed at the heated (and rifled) surface.