PSI - Issue 13

Zheng Miao et al. / Procedia Structural Integrity 13 (2018) 1043–1046 Author name / Structural Integrity Procedia 00 (2018) 000–000

1045

3

s a



(2)

P P   

ln

 



1

a s : parameter of the cavity growth model, 100GPa ； P : the mean pressure of unit, 100GPa; The relationship between the expansion degree and porosity of the material: 1 1     When the material contains damage in the form of tiny cavities, the pressure of the solid component in the representative unit is first calculated.   , s s s P P T   s P : pressure of solid ； s  :density of solid ； T :temperature ； Porosity is then used to average the pressure of the solid component to the whole representative unit.   1 s P P    (3) When the porosity of the material reaches the critical porosity, it is considered that the micropores in the material are inter connected to form macrocracks. At this time, the material is macroscopically fractured, the pressure and stress are zero, and the other physical quantities remain uncharged. 2.3. Modeling of spallation and verification of program The plane impact test of metal is simulated in 2 dimension Lagrange code. The result show that VG-Spall model can accurately distinguish the rebound signal in the free surface velocity curve. The physical quantity that is strong related to the spallation process, such as the rebound height and rebound position of the velocity curve, is in good agreement with the experiment result, which preliminarily verifies the correctness of the simulation in the spallation modeling. 2.4. Analysis of numerical result Figure 1 shows that the comparison between numerical simulation and experimental data. The first platform area of the free surface velocity curve is higher than the experimental data. Generally, the height of platform depends on the acoustic impedance and shock wave strength of the material. The theoretical calculation shows that the free surface velocity of target is 1.7km/s, is 10% higher than the measurement.

experiment-DISAR1 experiment-DPS3 Num

V(km/s)

10

15

20

25

30

TIME(  s)

Fig. 1. Velocity of numerical simulation and experimental data.

The numerical simulation results accurately capture the position and depth of the speed rebound. It shows that the description of the fracture behavior of the material layer in the VG-Spall model is basically in accordance with the physical facts. The limit porosity values selected can reflect the growth of the microporous holes in the material to the cumulative damage degree of the interpenetrating damage.