Fragmentation of metallic materials during impact
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Studies on shear-plug formation and on double-layered steel plates impacted by blunt-nosed hardened steel projectiles showed that at certain velocities against certain targetplates the projectiles shattered upon impact. This was not captured by the numeric simulations. From a design point of view, being able to break the projectile upon impact would be an impressive feature of a protective structure. From the component tests, it is evident that the compressed gas gun at SIMLab is an excellent tool for impact experiments. It is very predictable and can deliver the desired velocities at commmand. A fine set of experimental data was produced. Projectiles of three different degrees of hardness were launched at varying velocities in a series of Taylor tests to observe how they acted. The events were captured using a high speed camera. Lagrangian finite element simulations have been performed in an attempt to model the fragmentation process. The fragmentation itself has been modeled using cohesive elements.Fragmentation is a complex phenomenon depending on several different variables, makingit difficult to model and even harder to make the models general. Simulations show thatit is possible to recreate the some of the events from the lab experiments numerically. Material tests were carried out to provide data for the material and cohesive models used in the nite element simulations. Both a plastic-kinematic and the modified Johnson-Cook material models were used in addition to a cohesive model.