Analysis of the forces on infantry rifle housing via finite element method

The aim of the working principle of the infantry rifle, to explode the cartridge within the barrel housing, locking cartridge mechanism head in an appropriate tolerance and to eject the empty cartridge by the help of barrel gas pressure which reduced to the safe value after firing. The explosion of the cartridge in a safe manner and ejecting of empty cartridge depend directly on the head space dimensions and barrel material. There are three different weapon mechanisms including sudden retro driving, retro driving and gas operational to eject the empty cartridge automatically by weapon mechanism. In this study, the obtained behaviors of cartridge housing is investigated depending on the different materials and head space dimension as a result of the firing of ammunition in a gas operated gun. The aim of this study is to determine the head space tolerance which could operate safely in a rifle operating with a gas piston system that uses a 7,62x51 NATO normal cartridge for brass housing and to observe the behavior of housing after the firing and to analyze the change of the head space measurement when the housing material is steel. Furthermore, the properties of removability from the barrel are examined comparing with the housing contact pressure values between steel and brass barrel (housing). During the firing of ammunition, the bursting pressure and temperature after the explosion are experimentally determined. The pressure and temperature data obtained from the experimental studies are defined in finite element model and performed analysis. As a result of the performed studies, for the same dimensional barrel it is observed that instead of brass, using steel material, the tolerance of head space increased but the contract pressure between barrel and housing. According to the analysis results, it was determined that the service life of the rifle will be increase with the increment of head space dimensions depending on the head space tolerance and the empty cartridge will easily be removed from the rifle when using the brass material instead of steel housing .