Stress Analysis of Autofrettaged Midwall Cooled Compound Gun Tubes

Abstract

Analytical solutions for shrink-fit compound gun tubes were used to study the effects of the liner/sleeve interface diameter, the radial interference, and the effect of machining tolerances on tube strength. Finite element analyses were then done of a midwall cooled compound gun tube where a loose-fitting inner tube (liner) is permanently deformed by means of hydraulic pressure to lock it to the outer tube (sleeve). The interaction between the liner and sleeve was modeled with contact elements. The effect of machining subsequent to the hydraulic autofrettage was taken into account. Simulations were first done for smooth tubes with initial clearance of varying magnitude and, second, for the case where the liner has axial semi-circular cooling channels machined on its outer surface. Manufacturing tolerances were found to be much less critical for the hydraulic autofrettage than with the shrink-fit option. The interface diameter seems to be a relatively insensitive parameter. Relatively large initial clearance between inner and outer tubes can be tolerated. The hydraulic autofrettage option therefore seems better than the shrink-fit only option for compound gun tubes. It was demonstrated that the effect of the cooling channels on the stresses in the tube is significant and substantially weakens the inner tube. However, it is still possible to produce a workable design.

A residual stress analysis program using a Matlab GUI on an autofrettaged compound cylinder

“…In 2007, Lee and Park [3][4][5] studied and analyzed the Bauschinger effect about a compound cylinder. Swardt and Andrews [6] studied the stress analysis of autofrettaged midwall-cooled compound gun tubes in 2006.…”

The Application of Neutron Diffraction Techniques (NDT) in Measuring Residual Strain-Stresses of Engineering Materials

“…In order to enhance mechanical strength and in service integrity of engineering materials, variety of engineering metallic components are manufactured with special technique treatments, such as Autofrettaging [1], Hot Isostatic Pressing (HIP) [2] and Dissimilar Material Welding (DMW) [3]. The Autofrettaging technique utilizes plastic deformation mechanism to produce beneficial residual stresses, hence to increase load bearing capacity of an engineering component.…”

Solution of Heat Transfer Problem for Thick Walled Automatic Weapon Barrel Subjected to Continuous Firing

“…Repeated thermal effect will make the barrel bore geometry shape change. This may lead to a decrease the muzzle velocity, projectile stability, the firing accuracy and the tactical technical performance of the machine gun declining, [3]. Various mathematical methods are available for solving heat conduction in a composite medium, including Laplace transform method, [4,5], orthogonal expansion technique [6][7][8], Green's function approach, [9], line heat-source method, [10,11] and integral transform technique, [12] … etc.…”