Command manual

Command list

FUNCTION_STATIC

Parameters and functions
*FUNCTION_STATIC
fid
expression

Parameter definition

VariableDescription
fid Function ID
expression Analytical expression

Description

This command is used to define a field at time zero. The function is evaluated at each node or integration point during initialization. The values are accessible throughout the simulation and are typically used to define properties of functionally graded materials.

Example

Sphere with increased yield stress near the material surface

This is an example where the stress strain curve fcn(10) is defined to depend on the distance from the material surface. The distance to the material surface is automatically calculated at every integration point by the built in function dist_surf. The initial yield stress is A0+A1 on the material surface and it drops exponentially to A0 in the interior. Note that a static function fcn(20) is used to define the initial yield stress. The stress strain curve itself must not be static. It depends the effective plastic strain epsp and, hence, needs to be evaluated every time step.

*PARAMETER
%A0 = 500.0e6
%A1 = 300.0e6
%B = 400.0e6
%C = 500.0
%n = 0.3
*MAT_METAL
1, 7800.0, 210.0e9, 0.3
10
#
# Stress-strain curve
*FUNCTION
10
fcn(20) + %B*epsp^%n
#
# Initial yield stress
*FUNCTION_STATIC
20
%A0 + %A1*exp(-%C*dist_surf)
Functionally graded material
Functionally graded material
Sphere with increased yield stress near the material surface
Plate with variation in yield stress

This is an example where the stress strain curve fcn(10) is defined to depend on the distance from one of the plate surfaces. The distance is automatically calculated with dist_surf(xn,yn,zn). The arguments (xn,yn,zn) define an optional vector. The surface normal of all external element faces are compared to this vector. An element face is only active in the distance calculation if the angle between the face normal and (xn,yn,zn) is smaller than 70 degrees.

*PARAMETER
%A0 = 500.0e6
%A1 = 300.0e6
%B = 400.0e6
%C = 500.0
%n = 0.3
*MAT_METAL
1, 7800.0, 210.0e9, 0.3
10
#
# Stress-strain curve
*FUNCTION
10
fcn(20) + %B*epsp^%n
#
# Initial yield stress
*FUNCTION_STATIC
20
%A0 + %A1*exp(-%C*dist_surf(0,0,1))
Functionally graded material
Functionally graded material
Plate with variation in yield stress