Displacements out of node location
Displacements out of node location
(OP)
Hallo all,
I have a model of beam elements and I need to extract from the solution the displacements in some particular positions which do not coincide with the FE nodes.
How can I do this?
Andrea
I have a model of beam elements and I need to extract from the solution the displacements in some particular positions which do not coincide with the FE nodes.
How can I do this?
Andrea
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Andrea Mordini, Civil Engineer, Ph.D.
http://www.andreamordini.com
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RE: Displacements out of node location
no way. Export the results to Excel, then plot against longitudinal position, make a least-squares interpolation curve, take its equation and then apply it to the coordinates you need...
Equivalent workaround: make a path with a number of divisions set in such a way it matches the positions you want (if it is possible).
Regards
RE: Displacements out of node location
One can use the command
*MOPER,ParR,Par1,MAP,Par2,Par3
For example, you want to interpolate the displacements ux, uy and uz at Nout output nodes from the displacements of Nin nodes. Then you must define 4 array parameters:
! coordinate locations at which to interpolate.
*dim,Par1,array,Nout,3
! array containing the interpolated values
*dim,ParR,array,Nout,3
! array of values to be interpolated
*dim,Par2,array,Nin,3
! array of coordinate locations corresponding to the values in Par2
*dim,Par3,array,Nin,3
Regards,
Alex
RE: Displacements out of node location
RE: Displacements out of node location
Alex, great tip! I had totally forgotten it... a star for you!
Now I feel a bit stupid because in many analyses I also had to perform something like this and I did it with Excel... Well, I save myself in corner because by doing so I can obtain much better "operability" on my data as well as better graphs when needed...
Pja, you're also right, shape functions can be retrieved in any good FE-theory book, given that Ansys' theory manual describes the math each element type relies upon. But in this case it's only intra-element interpolation, for inter-element interpolation one has to do piecewise-functions interpolation or, as you say, *MOPER.
Thank you to all,
Regards
RE: Displacements out of node location
The problem is that *MOPER works over triangles (surfaces) and therefore, in case of linear elements it does not work...
I have tried with this trick: duplicate each node by moving it by a very small eps and apply the same value to be interpolated also to this node.
But in this case, the Par1 locations are always on the domain border and in some cases, probably due to numerical precision, the searching point are considered outside the domain resulting in very bad values...
andrea
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Andrea Mordini, Civil Engineer, Ph.D.
http://www.andreamordini.com
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RE: Displacements out of node location
RE: Displacements out of node location
There are 2 possibilities:
1) Like Pja said, shape functions
2) Define more beam elements, by dividig one beam element into more beam elements, so that you get nodes also at the inner locations. The you can directly get the displacements.
Regards,
Alex