Three-dimension Finite Element Analysis on State Difference Between Hot Gun and Cold Gun in Typical Small Caliber Rifle Barrel System

Abstract

Aiming at the difference of automatic rifle under the conditions of cold and hot gun,a typical small-caliber automatic rifle was taken as the research object in order to reveal the mechanism of cold and heat deviation and improve firing accuracy,and the research method based on thermal-solid coupling was used. The transient temperature and deformation of a typical small-caliber automatic rifle barrel system coated with Cr layer but ignoring the rifling were calculated under continuous thermal shock and chamber pressure. The variations of temperature field and displacement field along radial direction were analyzed. The simulation results were verified by the experimental data. The results show that the temperature gradient of each point in the inner chamber layer can cause a sharp change of thermal stress in high frequency during continuous firing; the thermal load is the main factor affecting the residual displacement; the peak displacement of the first few projectiles in the barrel system is mainly affected by the pulse displacement. With the increase of projectile quantity,the peak displacement is mainly affected by residual displacement. With the increase of projectile quantity,the deformation of barrel system in hot gun state is obviously larger than that in cold gun state,and the thermal load is the main reason affecting the deformation of barrel system. The pressure on the barrel system generates a displacement pulse that does not affect the residual displacement. The increase of residual displacement decreases with the amount of projectile.