Block Format Keyword
/MAT/LAW51 - Multi-Material ALE Law
Description
Up to four material laws can be defined: elasto-plastic solid, liquid, gas and detonation products. The material boundaries inside an element are not explicitly defined, but an anti-diffusive technique is used to avoid expansion of transition zone (/UPWIND in RADIOSS Starter Input).
LAW51 is only compatible with a 3D analysis with Euler or ALE formulation. It is not recommended to use this law with RADIOSS single precision engine.
Format
(1)
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/MAT/LAW51/mat_ID
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mat_title
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Blank
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Iform
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Material Law
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Formulation
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Number of
sub-materials
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Plasticity
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Explosive
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Iform=0
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3
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--
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--
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Iform=1
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3
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Johnson-Cook
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--
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Iform=10
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4
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Johnson-Cook
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Jones-Wilkins-Lee
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Iform=11
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4
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Johnson-Cook
Drücker-Prager
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Jones-Wilkins-Lee
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Elementary Boundary Conditions
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Formulation
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Type
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Iform=2
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INLET
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Iform=3
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OUTLET
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Iform=4
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GAS INLET (state defined from stagnation point)
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Iform=5
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LIQUID INLET (state defined from stagnation point)
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| 1. | Unlike most other materials, initial density is automatically computed from the densities and fractions of the various materials. |
| 2. | The anti-diffusive technique can be adjusted with /UPWIND from Starter Input. The  3 flag is the upwind coefficient for damp area: |
-1 < 3 < 1
3 = 1: Full Upwind (default value only)
3 = 1e-30: Zero Upwind (less diffusive, recommended value, if not unstable)
3 = -1: Full Downwind (Anti-Diffusive Technique, potentially unstable)
| 3. | For ALE applications, the time step coefficient is recommended to be 0.5. See /DT in Engine Input. |
| 4. | Artificial viscosity parameters qa and qb must be input through the property card /PROP/SOLID (like other materials). |
| 5. | This law can emulate Law 37 (liquid and gas mixture) with less diffusion. It can also be used to replace Law 20 for 3D Analysis (Law 20 is only compatible with 2D quad element). |
| 6. | LAW51 is based on the equilibrium between each material present inside the element. RADIOSS computes and outputs a relative pressure  . At each cycle: |
Total pressure can be calculated with external pressure:
| 7. | Material tracking is possible through animation files: |
/ANIM/BRIC/VFRAC (volumetric fractions)
| 8. | The following global outputs are available for animation files: |
/ANIM/BRICK/EPSP (global plasticity)
/ANIM/BRICK/TEMP (global temperature)
/ANIM/BRICK/BFRAC (High Explosive Burn fraction, if defined)
| 9. | It is recommended to use Streamline Upwind method for momentum advection to get rid of mesh dependency (see /UPWM/SUPG). |
| 10. | Tetra 4 elements can be used for this law, but BRICK elements are highly recommended for better numerical solution in ALE. |
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Material Hypothesis
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Output
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Modeling
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C0
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C1
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C2
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C3
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C4
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C5
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E0
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Pext
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Pmin
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Perfect gas
(Example 43)
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10-30
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-P0
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P0
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-P0
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10-30
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P0
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-P0
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Water
(Linear EOS)
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P0
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10-30
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P0
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-P0
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Linear Solid
(Linear EOS)
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P0
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P0
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Mie-Gruneisen
 constant
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K1
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K2
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K3
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- 1
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- 1
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E0
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P0
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Mie-Gruneisen
constant
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K1
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K2
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K3
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0
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0 - a
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E0
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P0
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Where,
Where,
 | is the total pressure and total energy formulation |
 | is the relative pressure and total energy formulation |
 | is the total pressure and relative energy formulation |
 | is the relative pressure and relative energy formulation |
| P0 | is the initial total pressure |
| E0 | is the initial total energy |
 | is the perfect gas constant |
 | is the poisson coefficient |
| is the Gruneisen’s gamma |
 | is the coefficient for first order approximation in Energy |
 | is the initial density |
| S | is the linear Hugoniot slope coefficient |
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See Also:
Material Compatibility
Example 46 - TNT Cylinder Expansion
Example 50 - INIVOL and Fluid Structure Interaction (Drop Container)
