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How to split selected nodes using APDL command?
 
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yeasin.bhuiyan
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Joined: 26 May 2015
Posts: 1
Location: USA

PostPosted: Tue May 26, 2015 9:14 am  Reply with quote

I have a solid model with appropriately meshed. Now I want to make a crack in a specified location. I want to do it by selecting the nodes on that location and splitting the nodes. (So, I am looking for an APDL command that do the opposite of NUMMRG,NODE command)
I am looking for an APDL command/s that can split the selected nodes.
I appreciate your help.
_________________
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YB
PHD student
University of South Carolina
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matt.sutton
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Joined: 21 Oct 2008
Posts: 134

PostPosted: Tue May 26, 2015 9:28 am  Reply with quote

YB,
I can't think of a specific command off the top of my head, but a series of N commands to create new nodes followed by EMODIF to replace an existing node in an element with the new node should get you there. You can use *get to figure out the index of a particular node in a given element to know the starting location for EMODIF. You can use NX(n), NY(n), NZ(n) to get the coordinates of an existing node for use in creating the new node at a coincident location. So, create a list of the nodes you want to operate on and then loop over them unzipping with the above approach as you go.
Matt Sutton
www.padtinc.com


-----Original Message-----
From: Xansys [mailto:xansys-bounces@xansys.org] On Behalf Of yeasin.bhuiyan
Sent: Tuesday, May 26, 2015 9:15 AM
To: xansys@xansys.org
Subject: [Xansys] How to split selected nodes using APDL command?

I have a solid model with appropriately meshed. Now I want to make a crack in a specified location. I want to do it by selecting the nodes on that location and splitting the nodes. (So, I am looking for an APDL command that do the opposite of NUMMRG,NODE command) I am looking for an APDL command/s that can split the selected nodes.
I appreciate your help.

------------------------
Best Regards
YB
PHD student
University of South Carolina






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fayaz.sofi
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Joined: 29 Dec 2014
Posts: 32

PostPosted: Tue May 26, 2015 10:33 am  Reply with quote

Hi Matt,

I used the below code lines previously to make a crack plane at any surface in any 3D-FE model. It worked well long back. You may like to see if it helps to script for your purposes.

Thanks,

Fayaz Sofi
Graduate Student at University of Nebraska-Lincoln


! MAIN CODE OF MACRO VALID FOR ALL ELEMENTS WRITTEN IN SMALL LETTERS

modmsh,nocheck ! Deactivate solid model checking.

cm,currelem_, elem ! Store current element selection.

cmsel,,cracknode_ ! Select crack face nodes.

cmsel,,face1_ ! Select elements on one crack face.

*get,numnode_,node,0,count ! Retrieve number of nodes in current set.

*do, loop1_, 1, numnode_, 1 ! Do loop for all nodes.
/GOPR

nnum_=ndnext(0) ! Retrieve lowest node number from current set.

newnode_=ndinqr(0,14)+1 ! Determine next available node number.

n,newnode_,nx(nnum_),ny(nnum_),nz(nnum_) ! Create new node.

esln,,0,ALL ! Select all elements using this node.

cmsel,u,face1_ ! Unselect elements from one face that uses this node.

nesel_=elmiqr(0,13) ! Get number of elements in current selection.

*do, loop2_, 1, nesel_, 1 ! Do for all elements connected to node.
/GOPR

ecrack1_=enextn(nnum_,1) ! Get next element to be modified.

*if, ecrack1_, eq, 0,exit ! Exit do loop when correct position is found.

*do, loop3_, 1, 20, 1 ! Do loop to find position number of node.
/GOPR

npos_=nelem(ecrack1_,loop3_) ! Get node number in position loop3_

*if, nnum_, eq, npos_, then ! Test if position loop3_ is correct for node.

posnum_=loop3_ ! If true, set posnum_ = to position number.

*exit ! Exit do loop when correct position is found.

*endif ! End if statement.

*enddo ! End do loop.

cm, work_, node ! Store current node set in temporary component.

nsle,,ALL ! Select nodes on current element.

nsel,a,node,,newnode_ ! Add new node to selection.

emodif, ecrack1_, -posnum_, newnode_ ! Change element connectivity to use new node.

cmsel,, work_ ! Restore working node set.

esel,u,elem,,ecrack1_ ! Remove modified element from selection.

*enddo ! End do loop.

nsel,u,node,,nnum_ ! Unselect current node number.

*enddo ! End do loop.

modmsh,check ! Restore solid model checking.

cmsel,,currelem_ ! Restore original element selection.

nsle,,ALL ! Select nodes on current element group.

! Delete components.

cmdele,work2_

cmdele,D_ELEMTS_

cmdele,face1_

cmdele,cracknode_

cmdele,currelem_




-----Original Message-----
From: Xansys [mailto:xansys-bounces@xansys.org] On Behalf Of Matt Sutton
Sent: Tuesday, May 26, 2015 11:27 AM
To: ANSYS User Discussion List
Subject: Re: [Xansys] How to split selected nodes using APDL command?

YB,
I can't think of a specific command off the top of my head, but a series of N commands to create new nodes followed by EMODIF to replace an existing node in an element with the new node should get you there. You can use *get to figure out the index of a particular node in a given element to know the starting location for EMODIF. You can use NX(n), NY(n), NZ(n) to get the coordinates of an existing node for use in creating the new node at a coincident location. So, create a list of the nodes you want to operate on and then loop over them unzipping with the above approach as you go.
Matt Sutton
www.padtinc.com


-----Original Message-----
From: Xansys [mailto:xansys-bounces@xansys.org] On Behalf Of yeasin.bhuiyan
Sent: Tuesday, May 26, 2015 9:15 AM
To: xansys@xansys.org
Subject: [Xansys] How to split selected nodes using APDL command?

I have a solid model with appropriately meshed. Now I want to make a crack in a specified location. I want to do it by selecting the nodes on that location and splitting the nodes. (So, I am looking for an APDL command that do the opposite of NUMMRG,NODE command) I am looking for an APDL command/s that can split the selected nodes.
I appreciate your help.

------------------------
Best Regards
YB
PHD student
University of South Carolina






+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+
+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+
+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

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uffe.eriksen
User


Joined: 21 Oct 2008
Posts: 69

PostPosted: Tue May 26, 2015 11:42 am  Reply with quote

One clever 'hack' is to use the PSMESH command, which is otherwise normally used for bolt pretensioning.

Look here (the 'Slicing your Mesh' article):

http://www.padtinc.com/blog/wp-content/uploads/oldblog/PADT_TheFocus_37.pdf
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Uffe Dal Eriksen
Ramboll Oil & Gas
Esbjerg, Denmark
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