CHANGE_P-ORDER

Nodes and connectivity
*CHANGE_P-ORDER
"Optional title"
entype, enid, order, gid
Parameter definition
VariableDescription
entype Entity type
options: P, PS, ALL
enid Entity identification number
order New element polynomial order
options: 1, 2, 3
gid ID of a GEOMETRY that defines a sub-space for change of polynomial order
default: No geometry. This means that all elements in the selected part/part set will change polynomial order
Description

Change element polynomial order in a selected region of a part or part set.

Example
Change of polynomial order

The following command defines a region in space where linear elements are converted to cubic.

*COMPONENT_BOX
1, 1, 20, 20, 2
0, 0, 0.45, 1, 1, 0.55
*PART
1, 1
*MAT_RIGID
1, 7800
*CHANGE_P-ORDER
P, 1, 3, 123
*GEOMETRY_PIPE
123
0.5, 0.5, 0.25, 0.5, 0.5, 0.75, 0.3
Linear vs. cubic elements

Two cantilever beams are subjected to a transverse point load at the unconstrained end. One of the beams is modeled with five LHEX (Linear hexagonal) elements and the other with five CHEX (Cubic hexagonal) elements. From Euler-Bernoulli beam theory, the maximum deflection, $\mathbf\delta_{max}$ is:

$\mathbf\delta_{max} = \displaystyle{ \frac{PL^3}{3EI} } = \displaystyle{ \frac{1.0e4 \cdot 1.0^3}{3 \cdot 200e9 \cdot \frac{0.05 \cdot 0.05^3}{12}} = 32 mm}$

where, $P$ is the applied load, $L$ is the length of the beam, $E$ is the elastic modulus and $I$ is the moment of inertia. The higher order elements are superior to the linear elements for this model setup.

*PARAMETER
%tend = 0.5, "Termination time"
%l = 1.0, "Length of the beam"
%t = 0.05, "Thickness of the beam"
%d = 0.1, "Distance value"
*TIME
[%tend]
*OUTPUT
[%tend/5]
*UNIT_SYSTEM
SI
*COMPONENT_BOX
"Linear elements"
1, 1, 5, 1, 1
0, 0, [-%d], [%l], [%t], [%t - %d]
*COMPONENT_BOX
"Cubic elements"
2, 2, 5, 1, 1
0, 0, [%d], [%l], [%t], [%t + %d]
*MAT_ELASTIC
1, 7800, 200e9, 0.3
*CHANGE_P-ORDER
P, 2, 3
*PART
1, 1
2, 1
#Fixed ends
*BC_MOTION
1
G, 1, XYZ
*GEOMETRY_SEED_COORDINATE
1
0, [%t/2], [%t/2 - %d]
*BC_MOTION
2
G, 2, XYZ
*GEOMETRY_SEED_COORDINATE
2
0, [%t/2], [%t/2 + %d]
# Prescribed force
11
G, 11, Y, 10
*GEOMETRY_SEED_COORDINATE
11
[%l], [%t/2], [%t/2 - %d]
12
G, 12, Y, 10
*GEOMETRY_SEED_COORDINATE
12
[%l], [%t/2], [%t/2 + %d]
*FUNCTION
10
smooth_d(%F_max, 0, 0.9*%tend)
*OUTPUT_SENSOR
"Linear"
1, 1, [%l], [%t/2], [%t/2 - %d]
*OUTPUT_SENSOR
"Cubic"
2, 2, [%l], [%t/2], [%t/2 + %d]
*CURVE
"Target"
10000
[0.0*%tend], 0.032
[1.0*%tend], 0.032
*END