炮药断裂韧性初探

高膛压炮的问世,对炮药的力学性能提出了更高的要求。本文根据炮药的性质、加工和使用的特点,探讨炮药断裂韧性的测定。

PRELIMINARY STUDIES ON FRACTURE TOUGHNESS OF GUN PROPELLANTS

Since the bore pressures of guns are high, we have to set much higher demands on the mechanical properties of gun propellants, especially the fracture toughness of gun propellants,In the course of production, stockpile and transportation, it is unavoidable to bring, some defects in the granules of propellant or on its surface. In order to ensure safety in using it, besides checking the basic data of its mechanical strength and analysing the stress under the flawless hypothesis, we must further study its fracture toughness. Otherwise, the crack of propellants may be enlarged by collision and induced shock waves and temperature gradients in the powder chamber, which in turn leads to abnormal combustion and unstable interior-ballistic process or to cause a breech blow up.An initial broadening of the crackle on the granule does not mean that it will be destroyed. Only when the extension force is so increased as to produce an unstable extension of the crack on it,the unexpected phenomena would happen.Therefore,we design a special compact tensile specimen with different crack depths and stretch it on an universal electronic testing machine under five different temperatures.The load p and displacement s are simultaneously recorded, and the results are treated by curve fitting procedure on a PC.The relation received between dimensionless crack lenghth (a/w) and corresponding dimensionless compliance (BEs/p) shows that the fracture toughness criteria Kc under different temperatures differs from one another. The temperatures of maximum Kcdiffer from one another, too. There is a tendency the higher the temperature of maximum Kc the higher hardness of the propellant.