Small Caliber Cartridge Case Chamber System Finite Element Analysis

In the evolution of automatic weapon, the design of cartridge-case and chamber systempossesses a very important position. The system composed of cartridge case and chamberis one of the essential parts of bullet. During the course of shooting, this system enduresvery heavy loads of high pressure and heat, which are generated from the power gas, andthe reliability of this system takes influence on the weapons performance directly. Incurrent research, aiming at the rupture problem engendered in the shooting process of acertain 5.56mm automatic rifle, the strain and stress distributions on the cartridge caseunder the action of axial pull have been analyzed. Based on the theories of elastic-plasticmechanics and contact mechanics, a mathematic and physical model of the cartridge-caseand chamber system has been set up; and based on the platform of the general softwarepackage APDL of ANSYS for finite element analysi's (FEA), a parameterized model of thecartridge-case and chamber system has also been established. The method for nonlinearFEA has been adopted to analyze the stress distribution on the entire cartridge-case andchamber system, and the method of contact element has been employed to investigate thecontact stress between the cartridge case and chamber, and then the influences of frictioncoefficient and locking space on the static and dynamic stress and strain response of thecartridge case and chamber to the action of power gas have also been discussed. On thebasis of a lot of numerical tests, a kind of element Plane13, which is concentrated incoupled computation of heat and construction, has been used finally to simulate thetransient response of the cartridge-case and chamber system to the power gas. Throughloading the temporary thermal characteristics of explosive gas in the procedure of emulate, the corresponding transient thermal stress distributed on the entire system under thecombined load of transient thermal stress and transient pressure has been obtained. Owingto these comprehensive considerations, the numerical results obtained in this paperrepresent the actual situations comparatively exactly. By analyzing these data, some usefulcognitions and conclusions of law and realistic effect, which can be referenced by futuredesign of ammunition system and firearms construction, have been acquired.