Iform = 1
Block Format Keyword This material is able to handle up to three elasto plastic materials (solid, liquid, or gas). The material law is based on a diffusive interface technique.
- P
- Positive for a compression and negative for traction.
Where, E=Eint/V0, C'2=C2δμ≥0 and C'3=C3δμ≥0 means that the EOS is linear for an expansion and cubic for a compression.
By default process is adiabatic δQ=0 . To enable thermal computation, refer to 6.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/MAT/LAW51/mat_ID/unit_ID | |||||||||
mat_title | |||||||||
Blank | |||||||||
Iform |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
Pext | ν | νvol |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat_10 | ρmat_10 | Emat_10 | ΔPmat_1min | Cmat_10 | |||||
C1mat_1 | C2mat_1 | C3mat_1 | C4mat_1 | C5mat_1 | |||||
Gmat_11 | amat_1 | bmat_1 | nmat_1 | ||||||
cmat_1 | ˙ε0mat_1 | ||||||||
mmat_1 | Tmat_10 | Tmat_1melt | Tlimmat_1 | ρCmat _ 1v | |||||
εmat _1 p,max | σmat_1max | Kmat_1A | Kmat_1B |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat_20 | ρmat_20 | Emat_20 | ΔPmat_2min | Cmat_20 | |||||
Cmat_21 | Cmat_22 | Cmat_23 | Cmat_24 | Cmat_25 | |||||
Gmat_21 | amat_2 | bmat_2 | nmat_2 | ||||||
cmat_2 | ˙εmat_20 | ||||||||
mmat_2 | Tmat_20 | Tmat_2melt | Tmat_2lim | ρCmat_2v | |||||
εmat _2 p,max | σmat_2max | Kmat_2A | Kmat_2B |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat_30 | ρmat_30 | Emat_30 | ΔPmat_3min | Cmat_30 | |||||
Cmat_31 | Cmat_32 | Cmat_33 | Cmat_34 | Cmat_35 | |||||
Gmat_31 | amat_3 | bmat_3 | nmat_3 | ||||||
cmat_3 | ˙εmat_30 | ||||||||
mmat_3 | Tmat_30 | Tmat_3melt | Tmat_3lim | ρCmat_3v | |||||
εmat _3 p,max | σmat_3max | Kmat_3A | Kmat_3B |
Definition
Field | Contents | SI Unit Example |
---|---|---|
mat_ID | Material identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit Identifier. (Interger, maximum 10 digits) |
|
mat_title | Material title. (Character, maximum 100 characters) |
|
Iform | Formulation flag. (Integer) |
|
Pext | External pressure. 2 Default = 0 (Real) |
[Pa] |
ν | Kinematic viscosity shear
ν=μ/ρ
. 3 Default = 0 (Real) |
[m2s] |
νvol | Kinematic viscosity (volumetric),
νvol=3λ+2μρ
which corresponds to
Stokes Hypothesis. 3 Default = 0 (Real) |
[m2s] |
αmat_i0 | Initial volumetric fraction. 4 (Real) |
|
ρmat_i0 | Initial density. (Real) |
[kgm3] |
Emat_i0 | Initial energy per unit
volume. (Real) |
[Jm3] |
ΔPmat_imin | Hydrodynamic cavitation pressure. 5 If fluid material ( Gmat_i1=0 ), then default = −Pext . If solid material ( Gmat_i1≠0 ), then default = -1e30. (Real) |
[Pa] |
Cmat_i0 | Initial pressure. (Real) |
[Pa] |
Cmat_i1 | Hydrodynamic coefficient. (Real) |
[Pa] |
Cmat_i2 | Hydrodynamic coefficient. (Real) |
[Pa] |
Cmat_i3 | Hydrodynamic coefficient. (Real) |
[Pa] |
Cmat_i4 | Hydrodynamic coefficient. (Real) |
|
Cmat_i5 | Hydrodynamic coefficient. (Real) |
|
Gmat_i1 | Elasticity shear modulus.
(Real) |
[Pa] |
amat _i | Plasticity yield stress. (Real) |
[Pa] |
bmat _i | Plasticity hardening
parameter. (Real) |
[Pa] |
nmat _i | Plasticity hardening exponent. Default = 1.0 (Real) |
|
cmat _i | Strain rate coefficient.
Default = 0.00 (Real) |
|
˙εmat_i0 | Reference strain rate. If ˙ε≤˙εmat_j0 , no strain rate effect (Real) |
[1s] |
mmat _i | Temperature exponent. Default = 1.00 (Real) |
|
Tmat_i0 | Initial temperature. Default = 300 K (Real) |
[K] |
Tmat_imelt | Melting temperature.
Default = 1030 (Real) |
[K] |
Tmat_ilim | Maximum temperature. Default = 1030 (Real) |
[K] |
ρCmat_iv | Specific heat per unit of volume. 7 (Real) |
[Jm3⋅K] |
εmat _i p,max | Failure plastic strain. Default = 1030 (Real) |
|
σmat_imax | Plasticity maximum stress. Default = 1030 (Real) |
[Pa] |
Kmat_iA | Thermal conductivity coefficient 1. 8 (Real) |
[Wm⋅K] |
Kmat_iB | Thermal conductivity coefficient 2. 8 (Real) |
[Wm⋅K2] |
▸Example
Comments
- Numerical diffusion can be improved using the second order method for volume fraction convection, /ALE/MUSCL. The previous /UPWIND used to limit diffusion is now obsolete.
- Radioss
computes and outputs a relative pressure
ΔP
.
(6) ΔP=max{ΔPmin, C0+C1μ+C'2μ2+C'3μ3+(C4+C5μ)E(μ)}However, total pressure is essential for energy integration ( dEint=−PdV ). It can be computed with the external pressure flag Pext.
P=ΔP+Pext leads to dEint=−(Pext+ΔP)dV .
This means that if Pext = 0, the computed pressure ΔP is also the total pressure: ΔP=P .
- Kinematic viscosities are global and is
not specific to each material. It allows computing
viscous stress tensor:
(7) τ=μ[(∇⊗V)+ t(∇⊗V)]+λ(∇V)IWhere,- ν=μ/ρ
- Cinematic shear viscosity flag
- νvol=3(λ+2μ3)ρ
- Cinematic volumetric viscosity flag
- Volumetric fractions enable the sharing
of elementary volume within the three different
materials.
For each material αmat_i0 must be defined between 0 and 1.
Sum of initial volumetric fractions ∑3i=1αmat_i0 must be equal to 1.
For automatic initial fraction of the volume, refer to the /INIVOL card.
-
ΔPmat_imin
flag is the minimum
value for the computed pressure
ΔP
. It means that total
pressure is also bounded to:
(8) Pmat_imin=ΔPmat_imin+PextFor fluid materials and detonation products, Pmat_imin must remain positive to avoid any tensile strength so ΔPmat_imin must be set to −Pext .
For solid materials, default value ΔPmat_imin = 1e-30 is suitable but may be modified.
- Heat contribution is computed only if the
thermal card is associated to the material law
(/HEAT/MAT).In this case, δQ=ρCVVdT and the parameters for thermal diffusion are read for each material:
(9) ρCmat_iV,Kmat_iA,Kmat_iB and Tmat_i0For solids and liquids, Cν≈Cp for perfect gas: γ=Cp/Cν
- The temperature evolution in the Johnson-Cook model is computed with the flag ρCmat_iV , even if the thermal card (/HEAT/MAT) is not defined.
- Thermal conductivity,
K
, is linearly dependent
on the temperature:
(10) K(T)=KA+KBT - Material tracking is possible through
animation
files:
/ANIM/BRIC/VFRAC (All material volumetric fractions)