Research Of Automatic Weapons Barrel Thermodynamics

Currently, the higher requirements on the accuracy of automatic weapon, During bulletlaunch, the gunpowder gases is as high as2000。C?3000。C in the barrel, and the propellantgas action time is usually only a few millisecond. It will produce a dynamic temperaturedifference effect between the inner surface of the barrel and beside of the inner surface. Thisdynamic temperature difference effect causes the inner surface produced very large stress. Incontinuous shooting, continuous pulsed with heat shock exacerbates the cumulative heat ofbarrel and appears the barrel thermal expansion. Large thermal stress and friction betweenbullet and barrel arises small cracks in the inner surface. Due to these reasons leads to reducedfiring accuracy and barrel life. This paper mainly study of thermodynamic properties of barrelunder pulse thermal shock and explore the related factors and regulation.This paper takes the7.62mm rifle as an example. Based on interior ballistic theory and heattransfer, finite element method, numerical simulation and thermodynamic model isestablished, and Dynamic, Temp-disp, Explicit method is used to make solution. Consideringthe material nonlinearity related to temperature, optimizing the mesh density, ensure theaccuracy of the simulation. On this basis, study the different rate of pulse width, pulsetemperature peak and pulse width on the thermodynamic properties such as barrel temperature,thermal stress and strain. Make use of the orthogonal experiment method to find out the shootspeed, number of shooting, gunpowder pulse peak and gunpowder pulse width to thesensitivity of barrel thermodynamic properties. Held in10shoots, the temperature pulse peakvalue and pulse width are more influential on the thermodynamic properties of barrel. Furtherthe dynamic equivalent model in the barrel is established. Study the projectile friction heateffect and barrel mechanical-thermal coupled thermodynamic properties. The influence offriction heat effect is far below than gunpowder thermal shock effect to the barrel thermodynamic properties. In continuous shooting, the thermodynamic properties of barreland various influencing factors of regulation, can guide the design of automatic weaponsystem matching with the projectile.