SPALL THROUGH VOID NUCLEATION, GROWTH AND COALESCENCE

Plate impact experiments, in the range 53-256 m/s, have been performed on leaded brass to study the process of ductile fracture under high r ates of strain. The material contains a dispersion of lead particles w hich serve as void nucleation sites and promote ductile fracture throu gh void nucleation, growth and coalescence. Spall was observed to occu r for impact velocities above 120 m/s. Recorded free surface velocitie s from VISAR measurements have been used to assess a model of ductile fracture based on the Gurson [1] yield function implemented within the LS-DYNA2D hydrocode. Good agreement is found between predicted and me asured spall velocities.