Mechanical properties at high strain-rate of lead core and brass jacket of a NATO 7.62 mm ball bullet

Abstract

Abstract. Numerical simulations are now an actual option in order to try to reproduce and understand the mechanical response in components subjected to extreme loading conditions, like in a ballistic impact. A correct materials calibration is therefore necessary in order to extract the materials parameters. In this work the simple and widely used Johnson-Cook model was used to analyse the experimental data obtained for the characterization of the bullet materials. The bullet under investigation is a full metal jacket ball, with a lead-antimony alloy core and a brass jacket. The experimental tests cover a wide range in strain-rate, starting from quasi-static tests up to high dynamic tests performed on a standard Split Hopkinson Pressure Bar setup. In general, there is a great lack in strain-rate sensitivity and failure data. Pure lead is very soft and ductile, so antimony is used to give greater hardness and strength. The results of this study show a significant strain-rate influence for this alloy that can be associated with the presence of the lead-antimony phases and their structures. Also in case of the brass the results showed significant strain-rate sensitivity in the material response.

Investigation about the influence of the mechanical properties of lead core and brass jacket of a NATO 7.62 mm ball bullet in numerical simulations of ballistic impacts

“…Formers projectile data collected from [7] have been summarized in Table 3. Present research new projectile data have been summarized in Table 4 [14]. It is worth to mention that the data in Table 4 are not exactly the data reported in [14] but are very similar.…”

“…Present research new projectile data have been summarized in Table 4 [14]. It is worth to mention that the data in Table 4 are not exactly the data reported in [14] but are very similar. The data in [14] are the last step of an optimization process; the data in Table 4 belong to an intermediate step.…”

“…Also considering the residual velocity of the bullet the authors obtain 771 m/s from experimental test, 778 m/s from numerical former data [7], 806 from numerical new data [14]. Again the reduce damage of the jacket, obtained during numerical simulation with new data [14], increases the residual velocity of the bullet.…”

“…4. Qualitative numerical\experimental comparisons between entry and exit holes using former bullet material data [7] and the new ones [14]. …”

“…Mechanical properties have been obtained by means of chemical composition identification and hardness tests, Table 3. Instead in present research improved material data have been used from a specific experimental campaign based on specimens made directly from lead and brass alloys of core and jacket obtained one step before the final manufacturing of the bullet [14]. Formers projectile data collected from [7] have been summarized in Table 3.…”