| Since being set up,the damage function model has successful application in the 1 -D simulation for spallation under impact loading.For extending the applicated field. and analysising the dynamic fracture, the damage function model is implemented in 2D finite element code—DEFEL, with which the spallation under impact loading and the spallation of metal cylinder under implosion loading, are simulated using criterion of critical damage.In the simulation of spallation in HR-2,2169 and 45 steels, The effect of strain-hardening and bauschinger is taken into account. The calculated free-surface velocity-time relation curves and stress-time relation curves are consistent with the experimental results. But the spall strength of materials from simulation is much larger than that from acoustical approximation (the former is 1.5 to 2 times of the latter),To explain the phenomena,it is advanced "theoretical spall strength" . It is shown that simulation is reasonable.It is simulated in the paper that steel cylinder under outer implosion loading, the cohesion athletics and spallation of steel cylinder is analyzised. The simulation results present the fracture position, kinetic characteristic curve of spall layer and remained layer.For the experiments that spall layer has little buckling,the calculated results are quite in accord with that of the experiments;for the experiments that spall layer has large buckling,the calculated remained layers results are in accord with that of the experiments,but the calculated spall layers results have deference with the expements.It is shown that from the simulation,for spall occurring,spall layer would get thinner as explosive thickness became smaller.It is shown that it is successful that the damage function model is implemented in 2D finite element code.It will become a important means to research the fracture under complex stresses.The paper extend the application of the damage function . |
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