Coloring By Material

[AidanMcConneheyOVT]

Hi everyone, I have a mesh comprised of multiple volume bodies with different materials. To be able to clearly identify the materials in the structure I'm hoping to plot the mesh with the elements color coded to their respective material. Currently when using the eplot() method, I am able to control the background color, but not the elements themselves. Attached below is my current attempt at this:

from ansys.mapdl.core import launch_mapdl

mapdl = launch_mapdl()
mapdl.prep7()

# ~~~ Basic Material ~~~ #
mapdl.mp("CTEX", 1, 2e-06)
mapdl.mp("EX", 1, 120000)
mapdl.mp("NUXY", 1, 0.28)

mapdl.mp("CTEX", 2, 4e-06)
mapdl.mp("EX", 2, 60000)
mapdl.mp("NUXY", 2, 0.28)
# ~~~ Parameters ~~~ #
x = 1
y = 1
z = 1

mDivs = 4
# ~~~ Element Types ~~~ #
mapdl.et(1, "PLANE42")
mapdl.et(2, "SOLID185")

# ~~~ Geometry Creation ~~~ #
mapdl.blc4(0, 0, x, y)
mapdl.lsla("S")
mapdl.lesize("ALL", ndiv=mDivs)
mapdl.amesh("ALL")

mapdl.type(2)
mapdl.extopt("ESIZE", mDivs / 2, 0)
mapdl.extopt("ACLEAR", 0)
mapdl.extopt("ATTR", 0, 0, 0)

mapdl.mat(1)
mapdl.vext("ALL", dz=z / 2)

mapdl.asel("S", "LOC", "Z", z / 2)
mapdl.mat(2)
mapdl.vext("ALL", dz=z / 2)

# ~~~ Assign Colors ~~~ #
mapdl.vsel("S", "MAT", '', 1)
mapdl.eslv()
mapdl.color(lab='ELEM', clab=3)

mapdl.vsel("S", "MAT", '', 2)
mapdl.eslv()
mapdl.color(lab='ELEM', clab=6)

mapdl.allsel()
mapdl.eplot(vtk=True)`

[mikerife]

Hi @AidanMcConneheyOVT
The 'color' command is a APDL command that does not affect the eplot command when using VTK to plot. It's only affects the native MAPDL plots. To plot the elements with materials color coded we can use PyVista. Well we need to import it first, so after importing launch_mapdl you can use:

import pyvista as pv

Then after the mapdl.allsel() command we can create an instance of the PyVista plotter and add the mesh. The mesh.grid automatically includes the material ID number for each element. So we just need to use the right field name for the scalars value.

plot = pv.Plotter()
plot.add_mesh(mapdl.mesh.grid, scalars='ansys_material_type')
plot.show()

The tricky part is setting your own color mapping. There are a lot of pre defined color maps. Or you can create your own list. But this will use the MAPDL PyVista Theme, which I think the color map is 'jet', so it looks more like a MAPDL result plot than a element plot with colors (cyan, red, etc). Anyway, if you want a custom color order we can work on that.
Mike

[AidanMcConneheyOVT]

That clears it up, thank you!

[AidanMcConneheyOVT]

As a follow up, let's say we were to want to plot the colors linked to a specific material property, for example the CTE or Young's Modulus. I know this functionality exists in base ANSYS mechanical as referenced from the workbench, but I'm curious how that could be built out in PyMPADL.

[mikerife]

@AidanMcConneheyOVT
So you want the value of the material property to be plotted? For one material model or more than one?

[AidanMcConneheyOVT]

For more than one, so for instance it would display these elements with the colormap corresponding to the material property. As an example, for a three-material analysis with 3, 6, and 9 ppm CTE for the materials, it would display as blue, green, and red if using the jet colormap

[mikerife]

@AidanMcConneheyOVT
I think I can be more efficient in getting the actual material property value into one big numpy array. And one entry for each element. But for a Friday this is not too bad...and it works.

from ansys.mapdl.core import launch_mapdl
import pyvista as pv
import numpy as np
import os

mapdl = launch_mapdl(port=50056)

pv.set_plot_theme('default')

mapdl.clear()
mapdl.prep7()

# ~~~ Basic Material ~~~ #
mapdl.mp("CTEX", 1, 2e-06)
mapdl.mp("EX", 1, 120000)
mapdl.mp("NUXY", 1, 0.28)

mapdl.mp("CTEX", 2, 4e-06)
mapdl.mp("EX", 2, 60000)
mapdl.mp("NUXY", 2, 0.28)

mapdl.mp("CTEX", 3, 8e-06)
mapdl.mp("EX", 3, 120000)
mapdl.mp("NUXY", 3, 0.28)

mapdl.mp("CTEX", 4, 1.2e-05)
mapdl.mp("EX", 4, 60000)
mapdl.mp("NUXY", 4, 0.28)

# ~~~ Parameters ~~~ #
x = 1
y = 1
z = 1

mDivs = 4
# ~~~ Element Types ~~~ #
mapdl.et(1, "SOLID185")

# ~~~ Geometry Creation ~~~ #
mapdl.blc4(0, 0, x, y, z)
mapdl.vgen(4, 'all', '', '', 2*x)

mapdl.lsla("S")
mapdl.lesize("ALL", ndiv=mDivs)

for item in range(1, 5):
    mapdl.mat(item)
    mapdl.vmesh(item)

mapdl.allsel()

# get values of cte into python list - was thinking I might need these
# then did not use them
cte = []
for mat in range(1, 5):
    cte.append(mapdl.get_value('ctex', mat, 0))


materials = np.unique(mapdl.mesh.material_type)
plot = pv.Plotter()
for mat in materials:
    mapdl.esel('s', 'mat', '', mat)
    mapdl.nsle('s')
    mat_cte = np.full((1, len(mapdl.mesh.nnum)), mapdl.get_value('ctex', mat, 0))
    plot.add_mesh(mapdl.mesh.grid, scalars=mat_cte, cmap='jet', n_colors=8)
mapdl.allsel()
plot.show()

mapdl.exit()