Page 290 - The Combined Finite-Discrete Element Method

COUPLED COMBINED FINITE-DISCRETE ELEMENT SIMULATION 273

0.45
0.4
Legend: 2 × 2 × 0.1 (m) block
0.35 Course mesh, m = 0.01 [kg]
Kinetic energy ( × 0.1 MNm) 0.25 Course mesh, m = 0.04 [kg]
0.3
Course mesh, m = 0.02 [kg]
Course mesh, m = 0.08 [kg]
Fine mesh, m = 0.01 [kg]
0.2
Fine mesh, m = 0.03 [kg]
Fine mesh, m = 0.08 [kg]
0.15
0.1

0.05
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Time (0.001 s)
Figure 8.9 Total kinetic energy of all solid fragments (versus time after ignition) for different
amounts of explosive.

3

2.5 Legend: 2 × 2 × 0.1 (m) block
Course mesh, m = 0.01 [kg]
Course mesh, m = 0.02 [kg]
2
Gas pressure (GPa) 1.5 1 Course mesh, m = 0.08 [kg]
Course mesh, m = 0.04 [kg]
Fine mesh, m = 0.01 [kg]
Fine mesh, m = 0.03 [kg]
Fine mesh, m = 0.08 [kg]

0.5

0
0 0.02 0.04 0.06 0.08 0.1
Time (0.001 s)

Figure 8.10 Pressure of detonation gas versus time after ignition for a 2 m square block.

The kinetic energy versus time diagrams for a series of explosive charges and different
discretisation grids are shown in Figure 8.9. The kinetic energy increases with the increase
in the amount of explosive used. In all the results shown, the specific explosive energy
of 6280 kNm/kg is employed.
The coupled simulation of explosive induced fragmentation also yields pressure, tem-
perature, density and the internal energy of the detonation gas. The detonation gas pressure
versus time for different amounts of explosive is shown in Figure 8.10. The pressure is