THERMAL EFFECT INFLUENCE ON BULLET ENGRAVING PROCESS AND INTERIOR BALLISTIC PROCESS

Abstract

The thermal effect cause by continuous firing of firearms, generally recognize have influence on the movement of bullets during in-bore process. In order to understand this influence. A finite element model coupled thermal and structure which contained bullet and barrel was established. Through the classical interior ballistic theory, the distribution and variation law of the boundary and load conditions parameters in the bore were determined, such as base pressure, propellant gas temperature, forced convection coefficient. By loading the boundary and load conditions at different positions in the barrel versus real time, the temperature distribution and deformation of the barrel after different initial temperatures and multiple continuous firing, the changes of the structure and movement parameters of bullets were calculated, and the model was validated by the temperature distribution of the barrel surface through the experimental test. The research shows that the thermal effect has a great influence on the engraving resistance of bullet, but the trajectory was little. The structural characteristics of the bullet change greatly with the increase of temperature. In addition, the thermal effect has a great influence on the vibration speed of the barrel muzzle, which may further affect the firing accuracy. Generally, when the barrel temperature is below 200 ℃ , the thermal effect has little influence, and when the barrel temperature is above 200 , the negative influence caused by the thermal effect increases linearly.