Thermo-mechanically coupled thermal and stress analysis of interior ballistics problem

Abstract

This study covers the interior ballistic solution of a 7.62 mm gun barrel based on shooting tests conducted using a test barrel and G3 rifle. The 3-D transient heat transfer and stress (thermal/mechanical) analysis were done using a thermo-mechanically coupled theory. The maximum pressure and muzzle velocity data of the test barrel were obtained via piezo-electric sensors and light screens, respectively. Using these data, Vallier–Heydenreich method was employed to determine the pressure, projectile velocity and position along the barrel. Pressure information was used with Noble–Abel equation to determine the temperature of burnt gases along the barrel. The convection heat transfer coefficient was determined using Vielle's burning equation. The commercial software program ANSYS was employed to get the temperature distribution in radial and axial directions of the barrel. The radial temperature distribution through the barrel wall thickness was validated by the temperature readings taken at the outer barrel surface using a FLIR thermal imager as a new and high precision method compared to the most generally used measuring methods with thermocouples. Pressure and temperature data along the barrel were employed in stress analysis to get the radial, circumferential and axial stresses. The results of the finite element (ANSYS) and analytical solutions were closely conforming to each other.