/MAT/PLAS

Block Format Keyword

/MAT/PLAS_ZERIL - Zerilli-Armstrong Elasto-Plastic Material

Description

This law defines an isotropic elasto-plastic material using the Zerilli-Armstrong plasticity model.

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)
C0	Plasticity yield stress (Real)
C5	Plasticity hardening parameter (Real)
n	Plasticity hardening exponent (Comment 5) Default = 1.0 (Real)
	Failure plastic strain Default = 1030 (Real)
	Plasticity maximum stress Default = 1030 (Real)
C1	Strain rate formulation coefficient (Real)
	Reference strain rate (must be 1 s-1 converted into user’s units) (Real)
ICC	Strain rate computation flag (Comment 7) (Integer) = 0: default set to 1 = 1: strain rate effect on = 2: no strain rate effect on
Fsmooth	Smooth strain rate option flag (Integer) = 0: no strain rate smoothing (default value) = 1: strain rate smoothing active
Fcut	Cutoff frequency for strain rate filtering (Comment 8) Default = 1030 (Real)
C3	Temperature effect coefficient (Real)
C4	Temperature effect coefficient (Real) = 0: no strain rate effect
	Specific heat per unit of volume (Real) = 0: temperature is constant: T = Tr
Tr	Room temperature Default = 298 K (Real)

1.	The Zerilli-Armstrong law is applicable only to shells and solids.

2.	The equation that describes stress during plastic deformation is:

Where, is plastic strain, is strain rate and T is the temperature.

3.	Yield stress should be strictly positive.

4.	When reaches in one integration point, then based on the element type:

•	Shell elements: The corresponding shell element is deleted.

•	Solid elements: The deviatoric stress of the corresponding integral point is permanently set to 0, however, the solid element is not deleted.

5.	n must be less than 1.

6.	If is 0, there is no strain rate effect.

7.	ICC is a flag of the strain rate effect on material maximum stress :

law_plaszeril

8.	Strain rate filtering input (Fcut) is only available for shell and solid elements.

9.	The strain rate filtering is used to smooth strain rates.

10.	Temperature is computed assuming adiabatic conditions:

where, Eint is the internal energy computed by RADIOSS.