How to add a keypoint inside the imported geometry

[YoonK39]

Dear all,

I have a problem with using PyMAPDL.

First, I was trying to select a cylindrical area.
Using the .asel command with the area number would be fine, but the geometry I'm going to use after is complicated, so I decided to make a keypoint and select the area using radius.

However, when I tried to make the keypoint, I am struggling with an error.


As you can see from the above figures, even though I set with different x and y coordinates, the keypoint's location remain the same.

# Boundary & Loading conditions
mapdl.csys(0)
mapdl.k(1000, x = 9.5,  y = 10.8, z = 0)
mapdl.k(1001, x = 29.5, y = -10.8, z = 0)
mapdl.allsel()
mapdl.lplot('ALL', show_keypoint_numbering=True, show_line_numbering=False)

This is my code. The origin of the coordinate is near keypoint 29.
The keypoint I'm trying to create is the center of the cylindrical area.
I don't know why this happen, since when I make keypoints at the blank space, it worked!

If anyone knows how to solve this problem, please let me know.
+) If anyone also knows how to select the cylindrical area without area number, please give me the information.

I'm waiting for the advice and help :)

[B-Naveen-Kumar]

@YoonK39 Try with this command

mapdl.wpoffs()

It works according to my understand from above.

[YoonK39]

Umm... Should I use the .wpoffs() right before using the .k() command?
Or between the .k() commands?

I am not used to using work planes, so can you please explain a little more? :((

[B-Naveen-Kumar]

Can you pls elaborate you requirement.?

[B-Naveen-Kumar]

! Example command to select areas based on shape

ASEL, S, AREA, , , , ! Select areas based on their shape

! Example: Select all areas for a cylindrical surface

ASEL, S, LOC, X, 0.0 ! Select all areas at x=0

[YoonK39]

I also tried to use the AREA and LOC, and it also went something wrong.
Even though the cylindrical area is between y = -19 and y = -1, when I use

# Boundary & Loading conditions
mapdl.asel('S', 'LOC', 'Y', -19, -1)

it says that there is no area chosen.
Then I tried with the below code,

# Boundary & Loading conditions
mapdl.asel('S', 'LOC', 'X', 0, 20)
mapdl.asel('R', 'LOC', 'Y', -20, 0)
mapdl.asel('U', 'LOC', 'X', 0)
mapdl.asel('U', 'LOC', 'X', 20)

and the last command seems not to be represented.

The angled rectangular areas should be not shown, but it doesn't.

[B-Naveen-Kumar]

Can you share your entire script.?

[YoonK39]

# import
import numpy as np
import pandas as pd
import pyvista as pv

from ansys.mapdl.core import launch_mapdl

# start mapdl
mapdl = launch_mapdl()

# reset mapdl & import geometry
mapdl.clear()
mapdl.units("SI")
mapdl.ignore_errors=True
mapdl.upload("D:\SYS-12.anf")
with mapdl.non_interactive:
    mapdl.run('/INPUT, SYS-12, anf')
mapdl.allsel()

# Define element attributes
# Second-order tetrahedral elements (SOLID187)
mapdl.prep7()
mapdl.et('ALL', "SOLID187")

# Define material properties of structural steel
E = 2.05e11  # Youngs modulus
NU = 0.29  # Poisson's ratio
CTE = 1.2e-5  # Coeff. of thermal expansion
mapdl.mp("EX", 'ALL', E)
mapdl.mp("PRXY", 'ALL', NU)
mapdl.mp("ALPX", 'ALL', CTE)

# Define mesh controls and generate mesh
mapdl.esize(0.001)
mapdl.vmesh('ALL')
mapdl.eplot()

grid = mapdl.mesh.grid

# Boundary & Loading conditions
mapdl.asel('S', 'LOC', 'X', 0, 20)
mapdl.asel('R', 'LOC', 'Y', -20, 0)
mapdl.asel('U', 'LOC', 'X', 0)
mapdl.asel('U', 'LOC', 'X', 20)
mapdl.cm('FIXED', 'AREA')
mapdl.aplot()

SYS-12.zip
I am also uploading the file together.

The thing I want to do was fixing one of the cylindrical area, and giving the load condition to another cylindrical area.

[mikerife]

Hi @YoonK39 @B-Naveen-Kumar
You don't need to create a key point in order to do this. Select the keypoints and work your way up to areas like so:

mapdl.ksel('s', 'kp', '', 1, 6)
mapdl.lslk('s', 1)
mapdl.asll('s', 1)
mapdl.nsla('s', 1)
mapdl.d('all', 'all', 0)
mapdl.cm('area_1', 'area')
mapdl.allsel()
mapdl.eplot(plot_bc=True, plot_bc_legend=True)

The element plot is then:

You can extend this to the other cylindrical hole.

Mike

[germa89]

You can select areas by location using mapdl.asel :

# Select areas between y == 2 and y == 4
mapdl.asel('S', 'LOC', 'Y', 2, 4)

[YoonK39]

Unfortunately, when I used the asel command several time, it doesn't work.
Like

mapdl.asel('S', 'LOC', 'Y', 2, 4)
mapdl.asel('A', 'LOC', 'X', 0, 4)
mapdl.asel('A', 'LOC', 'Z', 2, 4)

I want to know whether if I use the command several times, it doesn't work or not.

Thanks for your reply.

[mikerife]

@YoonK39
Yes, those commands will work. But is it possible that there are no areas whose picking location (centroid) is between 0 and 4 in current X direction? Or similar for the other commands. Maybe capture the output of those commands and print. Or list the areas between the commands.
Mike

[YoonK39]

@mikerife
I'm sorry I got the wrong example. I was focusing on another project so I confused.
My code and the result was like this.

mapdl.asel('S', 'LOC', 'X', 0, 20)
mapdl.asel('R', 'LOC', 'Y', -20, 0)
mapdl.asel('U', 'LOC', 'X', 0)
mapdl.asel('U', 'LOC',' Y', -1.5)

I want to eliminate the three square planes and only left the cylindrical surface but kept failed.

Did I write the code in a wrong way?

I had tried to select only the cylindrical surface for multiple time but I always end up with that figure.

[germa89]

Some things to check:

• Make sure your numbers are right. I mean the 0, 20, -20, -1.5 etc.
• Make sure that those areas are independent areas... they have not been merged. That could change their center location, and hence you might be using wrong locations.
• Alternatively, you can create a coordinate system (CS) in the center of the cylinder (mapdl.local), switch to that CS (mapdl.csys) and use select keeping in mind that the second dimension is the radial distance from the center of the CS. See this article for more info: https://www.padtinc.com/2012/05/23/coordinating-coordinate-systems-in-ansys-mechanical/