Rationalization of Ring Fragmentation Data via Simple Kinetic Energy Analysis

Abstract

AbstractThe available data on fragmentation of alloy rings at high strain rate has been reviewed and analysed with reference to a classical statistical and energetic model. The data have also been compared to a simple calculation based on the specific kinetic energy of the ring. It is shown that fragmentation data for alloys with over a 20 times difference in strength and 7 times difference in density scatter around a single curve when plotted as a function of specific kinetic energy over a wide range of strain rates. A fit to this curve therefore provides an approximate estimate of the expected fragment number for any ductile metal without requiring any detailed knowledge about the constitutive behaviour or defect population. This fit is better than a prediction based on the classical statistical model, and similar to that for the energetic model, which also requires a knowledge of the fragmentation fracture energy. The observation that specific kinetic energy alone can explain much of the difference observed between alloys suggest that the energy in the system is more important that details of the alloy microstructure or properties in controlling the number of fragments for a material that fails by ductile fracture. The fit does not work for a case where one alloy was heat treated to a condition where brittle failure occurred.