Ductile Fracture during Tensile Hopkinson Bar and Plate Impact Testing

The process of ductile fracture through void nucleation, growth and coalescence under strain rates in the range 1000 - 10000 1/s is studied. The material considered is UNS C36000 free cutting brass containing spheroidal lead particles which serve as void nucleation sites. Tensile Split Hopkinson Bar and Plate Impact tests have been performed to examine stress-strain and fracture behaviour under high rate loading conditions. This paper presents results from the mechanical testing and metallographic observations of damage within tested samples. Measured damage and spall strengths are compared with predictions using LS-DYNA2D calculations employing a Gurson-based constitutive model. The model is shown to provide good predictions of spall strength but is thought to over-predict void growth rates.