Study On The Relations Between The Dynamic Properties Of Two Alloy Steels And The Fragmentation Characteristics Of Exploded Cylinders

The research of fragmenting behavior of metal cylinder under internal explosive loading has very important value both theoretically and practically. The fragmenting behavior of a cylindrical structure is related to the dynamic performance of shell material and charge properties. In order to study the relations between properties of the explosive and the dynamic performance of shell material, this paper are as follows:Dynamic strength of six 401 and 823 steel under different heat treatment process were tested at strain rate of 104s-1 by using split Hopkinson pressure bar(SHPB), and the dynamic failure strains were calculated using Johnson-Cook failure equation.Fragmentation of a series of variable shells with different dynamic performance experiments were carried out under the internal explosive loading, and the initial velocity of fragments were tested. It shows that with the increasing of wall thickness, the fragment velocity have appeared a downward trend, but the velocity amplitude of shell with different dynamic performance fragment is different. Under the condition of the same wall thickness, fragment velocity increases with the optimization matching relation between dynamic strength and dynamic plasticity, shell fragment velocity produced most in large wall thickness of 4mm.The traditional Gurney formula for calculating the fragment velocity was modified using the method of dimensional analysis. And using the modified formula is reflected the different wall thickness of shell fragment velocity varies with the change of material performance.Different experimental conditions has been performed using finite element program of LS-Dyna. The fragment velocity data matched the experimental data well. And design a different materials, verified the relations between the fragment velocity and dynamic performance of shell materialsThe number and mass distribution of of the fragment was investigated using the method of image analysis approach. The results show that dynamical fracture mode dominated final mass distribution of fragments. Larger cylindrical shell tend to occur complicated forms such as tensile-shear mixed fracture and tensile fracture, lead to increase the size of the fragment, decrease in the number and quality of distribution.