Ram Accelerator Barrel Response to Transient Loads

Abstract

The ram accelerator is a hypervelocity launch system which uses a propulsive cycle similar to the one used in a ramjet engine. While the ram accelerator is structurally similar to a conventional gun, this combustion cycle creates a distinctly different pressure profile inside the barrel, and by extension a distinctly different stress and strain profile within the barrel itself. Finite Element Analysis (FEA) was performed using ABAQUS to investigate changes in barrel stress and strain due to transient loading conditions. The simulations showed maximum stress and strain decreasing with increasing projectile velocity, with maximum strain decreasing nearly 1.5 times more than the maximum stress despite remaining below the yield limit. Discontinuities in the inner surface of the barrel caused moderate increases to the maximum stress and strain. Testing also showed two specific velocities which created resonance responses within the system which amplified the stress and strain in the barrel.