Available at: https://digitalcommons.calpoly.edu/theses/986
Date of Award
MS in Aerospace Engineering
Several methods of increasing railgun barrel performance and lifetime are investigated. These include two different barrel-projectile interface coatings: a solid graphite coating and a liquid eutectic indium-gallium alloy coating. These coatings are characterized and their usability in a railgun application is evaluated. A new type of projectile, in which the electrical conductivity varies as a function of position in order to condition current flow, is proposed and simulated with FEA software. The graphite coating was found to measurably reduce the forces of friction inside the bore but was so thin that it did not improve contact. The added contact resistance of the graphite was measured and gauged to not be problematic on larger scale railguns. The liquid metal was found to greatly improve contact and not introduce extra resistance but its hazardous nature and tremendous cost detracted from its usability. The simulated resistivity augmented projectiles were able to mitigate harmful current build-up on the back of a projectile using different conductivity gradients. Within the range of conductivity of aluminum alloys no simulated gradient was able to fully level the current density, however, once the range was expanded to include the lower conductivity of titanium, nearly uniform current density was achieved.