| Budget Amount *help |
¥8,610,000 (Direct Cost: ¥7,800,000、Indirect Cost: ¥810,000)
Fiscal Year 2007: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2006: ¥5,100,000 (Direct Cost: ¥5,100,000)
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| Research Abstract |
Continuous-DEM (C-DEM) was proposed by enabling the reproduction of the deviatoric stress by introducing the concept of continuum mechanics. Simulations of impact problems, interaction between blast and metal, shock and water column was performed by the C-DEM. Validation of the suggested method and the code was carried out by comparing the results with theoretical and experimental results along with results obtained by reliable commercial codes. The conclusions of this study are summarized as follows.
1. Establishment of the Continuous-DEM
Improvement in the procedure of obtaining spring strains was conducted. This implement in the C-DEM enabled the DEM, usually applied to discontinuous analysis, to apply constitutive laws based on continuum mechanics calculation. Stabilization of the analytical results was additionally attained by application of artificial viscosities.
2. C-DEM validation by impact analysis
One-dimensional (1D) results of impact to rigid wall well agreed with theoretical
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values. Two-dimensional (2D) plastic deformation of metals has qualitatively reproduced experimental results. 1D impact problem was evaluated by comparing the results theoretically and by another method. The C-DEM and AUTODYN[○!R] showed good agreement in 2D impact between SUS 304 flyer and target.
3. Simulation of one-dimensional blast-metal interaction
The interaction between blast and metal was reproduced by exchanging pressure and particle velocity at the coupled boundary. While pressure and particle velocity obtained by the one-way analysis was overestimated in the case of contact detonation, the two-way analysis achieved good agreement with the AUTODYN[○!R]. In the case of standoff detonation, the weak blast resulted only small difference in terminal particle velocity. However, the wave propagation in the target may result pressure rise at the coupled boundary, suggesting necessity of two-way calculation in any case of coupled analyses.
4. Simulation of interaction between shock and water column
The simulation ended before deformation due to the instability of the interaction. The formation of vortex, however, denoted qualitative reproduction of the experiment. By conducting numerical experiments by substituting the cylindrical column with a quadrangular column, the water deformation and the development of the vortex was confirmed to mutually progress these particular events Less
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