Research On Barrel Life Technology

The barrel is the main component of the automatic weapon. Its role is to enable the bullet to get a relatively stable interior and exterior ballistics in the shooting process, and to enable the bullet to move forward with the high speed and rotate simultaneously, by which the bullet can obtain a specified muzzle velocity and the angular velocity required by the flight stability. The barrel is the key part of small arms which decides the muzzle velocity, angular velocity, firing angle and firing direction.Barrel life is the total number of bullets fired before losing its required tactical performances. When the weapon is fired continuously, the barrel is constantly under high temperature, high powder gas and the comprehensive mechanical actions of lateral press effect of rotation-guiding side of the bullet and other mechanical actions, which cause the erosion and wear of rifling constantly.With the increasing number of bullets fired, erosion and wear are also gradually increased, and the bore surface is destroyed gradually, which causes the ballistics performance of the fired bullet to decrease consequently. The deteriorated ballistic performances present themselves in decreased muzzle velocity, worse firing accuracy and flight stability, bigger ratio of elliptical holes. Erosive wear is one of the main reasons of barrel life. Important measures to reduce erosion in bore include improving the structures of inner bore surface and bullet, selecting the type of propellant and charge reasonably, etc. By means of the methods such as erosion reducing additives, surface treatment of bore and composite gun barrel, the barrel life can be improved effectively. The erosion mechanism of machine-gun barrel, its life trend and prediction are always be paid great attention and important studied issues, therefore, the studies of barrel life of large caliber machine-gun are of great significance.This article main research content is as follows:The main research contents are as follows:(1) The transient heat transfer model is established, and the heat conduction and thermal stress of tube are studied using the explicit difference scheme, and related results of barrel thermal stress are given;(2) The finite element models of the barrel with six round rifling, the barrel with six rectangular rifling, the barrel with six zigzag rifling, are established. The dynamic responses during forcing process under three conditions are solved by explicit integration method, and the damage situation and the forcing pressure of different bore structures are presented. By comparison, the simulation results are in good agreement with experiment results.(3) Based on the XFEM, the crack propagation of chrome plated layer of rifled barrel is simulated, and its further propagating direction and angle are predicted. By comparing the simulation results with the test results, the simulation results present enough precision. The simulation provides a way and method for the research of crack propagation.(4)The calculation method for gun barrel fatigue life is analyzed. The fatigue life of the rifled barrel is analyzed and calculated by the FE-safe software. The fatigue life nephogram and load safety factor are given.