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Iform = 2

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/MAT/LAW51 - Iform=2: Imposed Boundary State for Multi-Material ALE Law 51 (Iform = 0, 1, 10, or 11).

Description

This boundary material enables to impose sub-material states (density, energy, and volumetric fraction) which are also used to compute global material state. (Comment 1) Submaterial EOS parameters must be consistent with the ones in adjacent element (from the domain).

law51_iform2

Format

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/MAT/LAW51/mat_ID

mat_title

Blank Format

Iform

 

 

 

 

 

 

 

 

 

 

#Global Parameters

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Scaletime

PEXT

 

 

 

 

 

 

#Material1 Parameters

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E0mat_1

fct_IDsymbol_a_141

fct_IDdensity1

fct_IDE1

 

C1mat_1

C2mat_1

C3mat_1

C4mat_1

C5mat_1

C0mat_1

 

 

 

 

 

 

#Material2 Parameters

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E0mat_2

fct_IDsymbol_a_142

fct_IDdensity2

fct_IDE2

 

C1mat_2

C2mat_2

C3mat_2

C4mat_2

C5mat_2

C0mat_2

 

 

 

 

 

 

#Material3 Parameters

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E0mat_3

fct_IDsymbol_a_143

fct_IDdensity3

fct_IDE3

 

C1mat_3

C2mat_3

C3mat_3

C4mat_3

C5mat_3

C0mat_3

 

 

 

 

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

mat_ID

Material identifier

(Integer, maximum 10 digits)

 

mat_title

Material title

(Character, maximum 100 characters)

 

Iform

Formulation flag

(Integer)

 

Scaletime

Abscissa scale factor for input functions

Default = 1 (Real)

 

PEXT

External (ambient) pressure (Comment 2)

(Real)

 

Initial volumetric fraction (Comment 2)

(Real)

 

Initial density

(Real)

symbol_kg

E0mat_i

Initial energy per unit volume

(Real)

fail_energy

fct_IDsymbol_a_14i

Volumetric fraction evolution function identifier

Default: law51_volfrac

(Integer)

 

fct_IDdensityi

Density evolution function identifier

Default: law51_densfrac

(Integer)

 

fct_IDEi

Energy evolution function identifier

Default: law51_energyfrac

(Integer)

 

C1mat_i

Hydrodynamic coefficient

(Real)

symbol_Pa

C2mat_i

Hydrodynamic coefficient

(Real)

symbol_Pa

C3mat_i

Hydrodynamic coefficient

(Real)

symbol_Pa

C4mat_i

Hydrodynamic coefficient

(Real)

 

C5mat_i

Hydrodynamic coefficient

(Real)

 

Hydrodynamic cavitation pressure (Comment 3)

Default = -10-30  (Real)

symbol_Pa

C0mat_i

Initial pressure

(Real)

symbol_Pa
hmtoggle_plus1Comments
1.This formulation imposes sub-material states from user data.

Volumetric fraction:

Density:

Density Energy:

This enables to compute pressure from given polynomial EOS:

,

where P = symbol_dp + PEXT

and , which means that EOS is linear in expansion and cubic for in compression.

Also global material state is given by:

Pressure:

Density:

Energy:

2.Parameter PEXT enables you to take into account ambient pressure in case you want to work with relative pressure . This parameter is required by RADIOSS for correct energy integration at each cycle. Otherwise, numerical EOS solving is generally incorrect. It represents pressure which must be added to EOS calculation to obtain total (physical) pressure. It has no influence on pressure contour in animation files.

Example using linear EOS:

Total pressure: , and also PEXT = 0

Relative Pressure: , and also PEXT = Pamb

3.Volumetric fractions enable the sharing of elementary volume within the three different materials.

For each material must be defined between 0 and 1.

Sum of initial volumetric fractions must be equal to 1.

For automatic initial fraction of the volume, refer to /INIVOL.

4.If a function is not defined, then related quantity remains constant and set to its initial value. However, input quantity can be defined as time dependent function using provided function identifiers. Abscissa functions can also be scaled using Fscalet parameter which leads to use f(Scaletime * t), instead of f(t).
5. flag is the minimum value for the computed pressure.

Since P = symbol_dp + PEXT, defining PEXT = 0 implies symbol_dp = P and symbol_dpmin = Pmin.

Fluid materials pressure must remain positive to avoid any tensile strength, then

Pmin = 0 or symbol_dpmin = -PEXT

For solid materials, default value for = 1030 is suitable.