in pyansys how do I specify two element types?

James Derrick
James Derrick Administrator, Employee Posts: 283
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edited June 2023 in Structures

I have a pyansys script that creates a triangle area, with a 1D link to it. How do I give the area element one element type and the linking line another? (e.g. SOLID186 and LINK1).

I think an additional, relevant, question is what does the element type number mean?

from ansys.mapdl.core import launch_mapdl
mapdl = launch_mapdl()
mapdl.prep7()

k0 = mapdl.k(1, 0, 0)
k1 = mapdl.k(2, 0, 1)
k2 = mapdl.k(3, 1, 0)
mapdl.k(4, 2, 0)
mapdl.l(3, 4)
mapdl.a(k0, k1, k2)

enter image description here

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Answers

  • Pernelle Marone-Hitz
    Pernelle Marone-Hitz Member, Moderator, Employee Posts: 871
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    Answer ✓

    The element type enables the user to determine the physics involved with the element. For example, if you want to model a linear spring, you will need to use a COMBIN14 element.

    The line body could indeed be meshed with LINK1 (1-D) element. However the surface body cannot be meshed with solid elements (such as SOLID186). Maybe shell elements are what you are looking for (SHELL181 for example).

    Once you have decided the type of elements you want to use (COMBIN14, SOLID186, etc); you will need to define element type IDs : this is an identification number to tell MAPDL that a specific element type (and keyopts) will have to be used:

    ET,1,MESH200 defines that all elements of ID type 1 will be MESH200 elements.

    To mesh a structure with different element type IDs, you will need to activate the element type of interest to generate the mesh on the appropriate part. For example :

    ET,1,SHELL281 ! Element type n°1 is SHELL281 elements

    ET,2,LINK1 ! Element type n°2 is LINK1 elements

    MP,EX,1,210000 ! Define material properties (material 1, Young Modulus)

    MP,NUXY,1,0.3 ! Define material properties (material 1, Poisson Ratio)

    MP,DENS,1,3E-09 ! Define material properties (material 1, Density)

    TYPE,1 ! Activate element type n°1

    MAT,1 ! Activate material n°1

    AESIZE,ALL,50 ! Define mesh sizing

    AMESH,ALL ! Mesh all areas with active element type (element type 1, so SHELL281 elements)

    TYPE,2 ! Activate element type n°2

    MAT,1 ! Activate material n°1

    LMESH,ALL ! Mesh all lines with active element type (element type 2, so LINK1 elements)

  • Rohith Patchigolla
    Rohith Patchigolla Member, Moderator, Employee Posts: 212
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    Answer ✓

    We can associate an element attribute (such as element type, section etc) to an element, by issuing the commands like TYPE or SECNUM etc just before creating the element/generating the mesh.

    In the below script, I have added 2 element types and corresponding sections (needed for shell and beam/link elements) and associated them accordingly to respective elements.

    There are other ways ofcourse, but this is one of the way.

    from ansys.mapdl.core import launch_mapdl
mapdl = launch_mapdl()
mapdl.prep7()

#Keypoint definition
k0 = mapdl.k(1, 0, 0)
k1 = mapdl.k(2, 0, 1)
k2 = mapdl.k(3, 1, 0)
mapdl.k(4, 2, 0)

#Creating Geometry
line = mapdl.l(3, 4)
area = mapdl.a(k0, k1, k2)

#Element Types
mapdl.et(1,'Shell181')
mapdl.et(2,'Link180')

#Defining sections for shell and beam
mapdl.sectype(1,'shell')
mapdl.secdata(0.1)

mapdl.sectype(2,'link')
mapdl.secdata(0.1)

#Setting Element Attributes and Meshing
mapdl.esize(1)

mapdl.type(1)
mapdl.secnum(1)
mapdl.amesh(area)

mapdl.secnum(2)
mapdl.type(2)
mapdl.lmesh(line)

print(mapdl.etlist())
print(mapdl.elist())

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