Failure analysis of small caliber ammunition cartridge cracking after shooting test was carried out by means of macro check,microanalysis of fracture,element analysis,metallographic constituent assessing,and magnetic particle test.

in this paper a sectional ring parametricelement model of barrel and cartridge is constructedin accordance with the characteristics of varyingclearance and taper between the cartridge and barrel of the automatic weapon, and an incrementalelasto-plastic finite element equation is established.

The analysis for emission stresses of cartridge cases is a complicated nonlinear interaction between cartridge and tube.

In the paper the no linear FEA is used to calculate the stress of cartridge cases in emission and the forces for extraction.

But the strength of the cartridge case after ironing drawing cannot be accurately calculated by this formula,because the result of calculation is lower than that reached in practice.

The existing problem of the scathing of metal cartridge case during port-tightening was analyzed.

On the basis of theoretical and experimental result of closed bomb, the burning rate formula of combustible case is studied.

Based on the analysis of p～t curve s initial section which is obtained from the closed-bomb,this paper gets the difference of ignition characteristics about three types of combustible cases,compares the ignition delay time with theoretical results, then suggests a method to judge ignition by looking for the deflection point of initial section of P～t curve.

The paper gives the mixed loading constructure of combustible case and propellants and studies the energy emission of cartridge with combustible case after burning,then analyses the matching quality between combustible case and propellants.