Iform = 10
Block Format Keyword Able to handle up to four materials: Three elasto-plastic materials (solid, liquid, or gas), and one high explosive material (JWL EOS).
The material law is based on a diffusive interface technique. For sharper interfaces between submaterial zone, refer to /ALE/MUSCL.
It is not recommended to use this law with Radioss single precision engine.
- P
- Positive for a compression and negative for traction.
Where, E=Eint/V0, C'2=C2δμ≥0 and C'3=C3δμ≥0 mean that the EOS is linear for an expansion and cubic for a compression.
By default, the process is adiabatic δQ=0 . To enable thermal computation, refer to 6.
Where, V is relative volume: V=Volume/V0 and E is the internal energy per unit initial volume: E=Eint/V0 . 9 to 13
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 _1 min | Cmat _ 10 | |||||
Cmat _ 11 | Cmat _ 12 | Cmat _ 13 | Cmat _ 14 | Cmat _ 15 | |||||
Gmat _ 11 | amat_1 | bmat_1 | nmat_1 | ||||||
cmat_1 | ˙εmat _ 10 | ||||||||
mmat _ 1 | Tmat _ 10 | Tmat _ 1melt | Tmat _ 1lim | 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 _2 min | 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 _3 min | 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 |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
αmat _ 40 | ρmat _ 40 | Emat _ 40 | ΔPmat _4 min | Cmat _ 40 | |||||
A | B | R1 | R2 | ω | |||||
D | PCJ | Cmat _ 41 | IBFRAC |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
mat_ID | Material
identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit Identifier (Integer, 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 _i min | Hydrodynamic cavitation
pressure. 5 If fluid material ( Gmat _i 1=0 ), then default = -Pext If solid material ( Gmat _i 1≠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.
9 (Real) |
[Pa] |
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_i0 , 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 _i max | 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] |
αmat _40 | Initial volumetric
fraction of unreacted explosive. 4 (Real) |
|
ρmat _40 | Initial density of
unreacted. explosive (Real) |
[kgm3] |
Emat _40 | Detonation
energy. (Real) |
[Jm3] |
ΔPmat _4min | Minimum pressure. 5 Default = −Pext (Real) |
[Pa] |
Cmat _40 | Initial pressure of
unreacted explosive. (Real) |
[Pa] |
A | JWL EOS
coefficient. (Real) |
[Pa] |
B | JWL EOS
coefficient. (Real) |
[Pa] |
R1 | JWL EOS
coefficient. (Real) |
|
R2 | JWL EOS
coefficient. (Real) |
|
ω | JWL EOS
coefficient. (Real) |
|
D | Detonation velocity. | [ms] |
PCJ | Chapman-Jouget
pressure. (Real) |
[Pa] |
Cmat _41 | Hydrodynamic coefficient
for unreacted explosive. 9 (Real) |
[Pa] |
IBFRAC | Burn Fraction Calculation
flag. 11
(Integer) |
Example
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/LAW51/99
99.99% Water + 0.01% Air-MULTIMAT:AIR+WATER+TNT,units{kg,m,s,Pa}
#(output is total pressure:Pext=0)
#--------------------------------------------------------------------------------------------------#
# Material Law No 51. MULTI-MATERIAL SOLID LIQUID GAS -ALE-CFD-SPH
#--------------------------------------------------------------------------------------------------#
# Blank format
# IFORM
10
#---Global parameters------------------------------------------------------------------------------#
# P_EXT NU LAMDA
0 0 0
#---Material#1:AIR(PerfectGas)---------------------------------------------------------------------#
# ALPHA_1 RHO_0_1 E_0_1 P_MIN_1 C_0_1
0.0001 1.2 2.5E+05 0 0
# C_1_1 C_2_1 C_3_1 C_4_1 C_5_1
0 0 0 0.4 0.4
# G_1 SIGMA_Y_1 BB_1 N_1
0 0 0 0
# CC_1 EPSILON_DOT_0_1
0 0
# CM_1 T_10 T_1MELT T_1LIMIT RHOCV_1
0 0 0 0 0
# EPSILON_MAX_1 SIGMA_MAX_1 K_A_1 K_B_1
0 0 0 0
#---Material#2:WATER(Linear_Incompressible)--------------------------------------------------------#
# ALPHA_2 RHO_0_2 E_0_2 P_MIN_2 C_0_2
0.9999 1000.0 0 0 1E+5
# C_1_2 C_2_2 C_3_2 C_4_2 C_5_2
2.25E+9 0 0 0 0
# G_2 SIGMA_Y_2 BB_2 N_2
0 0 0 0
# CC_2 EPSILON_DOT_0_2
0 0
# CM_2 T_20 T_2MELT T_2LIMIT RHOCV_2
0 0 0 0 0
# EPSILON_MAX_2 SIGMA_MAX_2 K_A_2 K_B_2
0 0 0 0
#---Material#3:not defined Plastic material with Johnson-Cook Yield criteria-----------------------#
# ALPHA_3 RHO_0_3 E_0_3 P_MIN_3 C_0_3
0.0 0 0 0 0
# C_1_3 C_2_3 C_3_3 C_4_3 C_5_3
0 0 0 0 0
# G_3 SIGMA_Y_3 BB_3 N_3
0 0 0 0
# CC_3 EPSILON_DOT_0_3
0 0
# CM_3 T_30 T_3MELT T_3LIMIT RHOCV_3
0 0 0 0 0
# EPSILON_MAX_3 SIGMA_MAX_3 K_A_3 K_B_3
0 0 0 0
#---Material#4:TNT(JWL)----------------------------------------------------------------------------#
# ALPHA_4 RHO_0_4 E_0_4 P_MIN_4 C_0_4
0.0 1590 7.0E+9 1E-30 1.0E+05
# B_1 B_2 R_1 R_2 W
371.20E+9 3.231E+9 4.15 0.9499 0.3
# D P_CJ C_14 I_BFRAC
6930.0 2.1E+10 22.5E+5 0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
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
.
(7) 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 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:
(8) τ=μ[(∇⊗V)+ t(∇⊗V)]+λ(∇V)IWhere,- ν=μ/ρ
- Kinematic shear viscosity flag
- νvol=3(λ+2μ3)ρ
- Kinematic 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:
(9) 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.
- By default, the
process is adiabatic:
δQ=0
. 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:
(10) 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:
(11) K(T)=KA+KBT -
Cmat_41
can be estimated 1 with
(12) Cmat_41= ρ0mat_4⋅ (cunreacted0)2Where, cunreacted0 is the speed of sound in the unreacted explosive and an estimation for TNT is 2000 m/s.
- Explosive material ignition is made with detonator cards, /DFS/DETPOINT or /DFS/DETPLAN.
- Detonation
Velocity (D) and Chapman Jouget Pressure
(PCJ) are used to compute
the burn fraction calculation (
Bfrac∈[0,1]
). It controls the release of detonation energy
and corresponds to a factor which multiplies JWL pressure.
For a given time: P(V,E)=BfracPjwl(V,E) .
A detonation time Tdet is computed by the Starter from the detonation velocity. During the simulation the burn fraction is computed as:(13) Bfrac=min(1,max (Bf1,Bf2))Where, the burn fraction calculation from burning time is:(14) Bf1=1−V1−VCJ=ρ0 D2PCJ(1−V)and the burn fraction calculation from volumetric compression is:(15) Bf2={0,x<0T−Tdet1.5Δx,x≥0It can take several cycles for the burn fraction to reach its maximum value of 1.00.
Burn fraction calculation can be changed defining the IBFRAC flag:
IBFRAC = 1: Bfrac=min(1,Bf1)
IBFRAC = 2: Bfrac=min(1,Bf2)
- As of version
11.0.240, Time Histories for Detonation time and burn fraction are available
through /TH/BRIC with BFRAC
keyword. This allows to output a function
f
whose first value is detonation time (with
opposite sign) and positive values corresponds to the burn fraction
evolution.
(16) Tdet=−f(0)Bfrac(t)={ 0, f(t)<0f(t), f(t)≥0 - Detonation times can be written in the Starter output file for each JWL element. The printout flag (Ipri) must be greater than or equal to 3 (/IOFLAG).
- Material tracking
is possible through animation files:
/ANIM/BRICK/VFRAC (volumetric fractions for all materials)