/MAT/LAW21 (DPRAG)

Block Format Keyword

/MAT/LAW21 - Rock-Concrete Material

Description

This law, based on Drücker-Prager yield criteria, is used to model materials with internal friction such as rock-concrete. The plastic behavior of these materials is dependent on the pressure in the material. This law is similar to LAW10 (/MAT/DPRAG1); the only difference being that in this law, the pressure is input as a user-defined function of volumetric strain. This law is compatible only with solid elements.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW21/mat_ID/unit_ID or /MAT/DPRAG/mat_ID/unit_ID
mat_title

E
A0		A1		A2		Amax
fct_IDf		Kt		FscaleP
		Pext
B

Field	Contents	SI Unit Example
mat_ID	Material identifier (Integer, maximum 10 digits)
unit_ID	Optional unit identifier (Integer, maximum 10 digits)
mat_title	Material title (Character, maximum 100 characters)
	Initial density (Real)
E	Young’s modulus (Real)
	Poisson’s ratio (Real)
A0	Material plasticity coefficient (Real)
A1	Material plasticity coefficient (Real)
A2	Material plasticity coefficient (Real)
Amax	Limiting von Mises stress Default set to 1030 (Real)
fct_IDf	Function identifier describing P() (Integer)
Kt	Tensile bulk modulus (Comment 3) (Real)
FscaleP	Pressure function scale factor Default = 1.0 (Real)
	Minimum pressure Default = -1030 (Real)
Pext	External pressure (Comment 4) Default = 0 (Real)
B	Unloading bulk modulus (Comment 3) (Real)
	Maximum volumetric strain in compression (Comment 5) (Real)

#RADIOSS STARTER

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/UNIT/1

unit for mat

Mg mm s

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#- 2. MATERIALS:

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/MAT/DPRAG/1/1

Sand

# RHO-I

1.6E-9

# E NU

100 .3

# A0 A1 A2 Amax

1E-7 .001 1 0

# fct_IDf Kt Fscale_p

2 1 0

# P_min

-1.5E-4

# B Mu_max

80 .4

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#- 3. FUNCTIONS:

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/FUNCT/2

Sand

# X Y

-1 0

0 0

.1 1000

.2 2500

.3 5000

.4 10000

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#ENDDATA

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

1.	Hydrodynamic behavior is given by a user-defined function P = f().

where, P is the pressure in the material, and is the volumetric strain.

mat_law10A

2.	Drücker-Prager yield criteria uses a modified von Mises yield criteria to incorporate the effects of pressure for massive structures:

mat_law10B

Where, J2 is the second invariant of deviatoric stress, P is the pressure, A0, A1, and A2 are the material plasticity coefficients, and A1 = A2 = 0 means that yield criteria is von Mises ().

3.	It is recommended to set Unloading Bulk modulus, B is equal to the initial slope of function describing P() and Tensile Bulk modulus Kt equal to 1/100 of Unloading Bulk modulus B and Kt must be positive.

External pressure is needed in case of relative pressure formulation. In this specific case, yield criteria and energy integration require total pressure value. RADIOSS outputs a pressure which is relative to Pext. You can conclude the total pressure value from P = Pext +

where,

is EOS calculation. Total pressure limit is concluded from Plim = Pext +

lim.

If Pext = 0, then output result is a total pressure: P = and Plim = lim .

5.	If B = 0 and = 0, the unloading path and the loading path are the same.

If B = 0 or ≠ 0, the default value for B is .

If B ≠ 0 or = 0, the default value for is .

loading_unloading

If B is defined, then it must be greater than any slope in [0; ].

/MAT/LAW21 (DPRAG)

/MAT/LAW21 (DPRAG)

/MAT/LAW21 (DPRAG)

See Also: