Critical damage degree model of spall fracture in ductile metals

A critical damage degree model was established for spall fracture in high-purity ductile polycrystalline metals. Three critical characteristic damage degrees (i.e., nucleation, complete plasticity, and fracture damage) were used to divide the dynamics of damage evolution into four stages: void nucleation, elastoplastic growth, plastic growth, and coalescence. For each stage, a physical model was established based on the damage evolution regularities and mechanism. Simulated results of the proposed model coincided well with the experimental ones in terms of serious spall experiments for oxygen-free copper. Finally, the association between the characteristics of the pullback signal in the spall experiment and the dynamic properties of damage evolution is discussed, indicating that the three critical damage degrees in the model had definite physical meanings.