Analysis And Research On Bending Deformation Of A Large Caliber Sniper Rifle

To the influence of barrel of some 12.7mm sniper rifle on the firing accuracy, the barrel bending by its dead weight, the thermal bending from different ambient temperatures and solar radiation, and the changing mechanism of thermal dynamics of barrel under different temperature environments, and the above influence upon the firing accuracy were analyzed.Firstly, the bending deformations, including the bending angle and displacement of gun muzzle, caused by the barrel dead weight were calculated by theoretical method and numerical calculation. By further analysis of bending deformations under different firing angles, the relation between firing angle and bending deformation was obtained.The reasons causing the thermal bending of sniper rifle barrel were analyzed from two aspects emphatically. The first was uniform bending by ambient temperature. The thermal expansions under different ambient temperatures were calculated by FEM numerical solution. By further coupling with the dead weight of sniper rifle barrel, the coupling bending deformations of barrel under different ambient temperatures were calculated. The second was the non-uniform heating of gun barrel by solar radiation. The transient thermal-fluid-solid coupling calculation to the barrel of sniper rifle in a spatial domain was calculated by CFX and ANSYS. Calculation results showed the steady temperature difference between the upper surface and lower surface of barrel was produced. The coupling effect of this temperature difference with barrel dead weight could produce bending angle of muzzle with about 0.3mil, which had obvious influence on firing accuracy. Based on the above work, the characteristics of thermal dynamics of barrel of sniper rifle were studied. The natural frequencies and the corresponding vibration modes of barrel under different ambient temperatures were numerically calculated by FEM. With the obtained vibration modes as basic parameters, the thermal vibration characteristics of barrel, such as harmonic response, shock vibration response, random vibration response, etc, under different temperatures, were calculated.In summary, the deep studies of barrel bending deformation of sniper rifle caused by different ambient temperatures, solar radiations, barrel dead weight and their coupling effects were calculated. The new research thinking and method were provided. The obtained results supplied the basis and solving method for the firing correcting and the improvement of firing accuracy of sniper rifle, and were of great theoretical value and engineering value.