A physical criterion of dynamic tensile fracture has been introduced, based on the knowledge of the micro-mechanism and the measurement of the damage evolution. The physical criterion has suggested two critical damage parameters, named as the critical void coalescence damage D_l and the critical fracturing damage D_f. These two parameters are associated with a damage function model and a percolation-softening function, by which the fracture process is characterized as that the damage slowly increases in a linear manner from the initial state (D=D₀) to the void linkage state (D=D_l), then changes to a nonlinear growth and rapidly approaches to the critical fracturing state (D=D_f), while a final step catastrophically leads to the complete fracture state (D=1.0). Experimental measurements and numerical simulations for both of the plate impact and the cylindrical tube have verified that these two parameters (D_l and D_f) physically constrain the dynamic tensile fracture and may be considered as the intrinsic material constant. Application of this physical criterion for the prediction of dynamic tensile fracture under intricate loading and for complex geometrical system has been discussed.

tensile fracture  /  damage evolution  /  physical criterion