Title:
Gas gun studies of armature-rail interface wear effects

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dc.contributor.advisor Thadhani, Naresh N.
dc.contributor.author Jackson, Tyler Andrew en_US
dc.contributor.committeeMember Cowan
dc.contributor.committeeMember Danyluk
dc.contributor.committeeMember Rosen
dc.contributor.department Mechanical Engineering en_US
dc.date.accessioned 2011-03-04T20:58:23Z
dc.date.available 2011-03-04T20:58:23Z
dc.date.issued 2010-11-18 en_US
dc.description.abstract The objective of this work has been to investigate the applicability of the gas gun to study the armature-rail interface wear characteristics relevant to rail gun operations. The approach involved developing constitutive models for armature materials (aluminum 6061) as well as oxygen-free high-thermal conductivity copper as the rail material. Taylor rod-on-anvil impact experiments were performed to validate the accuracy of constitutive strength models by correlating predictions of dynamic simulations in ANSYS AUTODYN with experimental observations. An optical comparator was used to discretize the cross sectional deformation profile of each rod-shaped sample. Parameters of the Johnson-Cook strength model were adjusted for each material to match deformation profiles obtained from simulations with profiles obtained from impact experiments. The fitted Johnson-Cook model parameters for each material were able to give overall deformed length and diameter values within 2% of the experimentally observed data. Additional simulations were then used with the validated strength model parameters to design the geometry involving cylindrical rods of armature material accelerated through a concentric cylindrical extrusion die made of copper, to emulate the interface wear effects produced in a rail gun operation. Experiments were conducted using this geometry and employing both the 7.62mm and 80mm diameter gas guns. Microstructural analysis was conducted on interfaces of the recovered samples from both designs. Hardness measurements were also performed along the interface layer to evaluate the structure formation due to solid-state wear or melt formation. The stress and strain conditions resulting in the observed microstructural effects were correlated with predictions from numerical simulations performed using the validated material models. The overall results illustrate that the stress-strain conditions produced during acceleration of Al through hollow concentric copper extrusion die, result in interface deformation and wear characteristics that are influenced by velocity. At velocities (less than 800m/s), interface wear leads to formation of layer dominated by solid-state alloying of Cu and Al, while higher velocities produce a melted and re-solidified aluminum layer. Hence, use of different armature (Al-based) and rail (Cu-based) materials can be evaluated with the gas-gun set-up employed in the current work to study the effects of interface wear ranging from formation melt layer to solid-state alloying as a function of material properties and velocity. en_US
dc.description.degree M.S. en_US
dc.identifier.uri http://hdl.handle.net/1853/37223
dc.publisher Georgia Institute of Technology en_US
dc.subject Gas gun en_US
dc.subject Armature-rail en_US
dc.subject Taylor test en_US
dc.subject.lcsh Armatures
dc.subject.lcsh Electromagnetic devices
dc.subject.lcsh Mechanical wear
dc.title Gas gun studies of armature-rail interface wear effects en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Thadhani, Naresh N.
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication ec14adca-203a-4973-b6ac-65dab1b1f44d
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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