Defining a circle
Defining a circle
(OP)
Hello everyone.
Does anyone know how to define a circle (a face) in the input file. I have been able to define the basic shape of a semi-circle, but i am having difficulty with generating the nodes and elements.
Any help would be greatly appreciated
Thank You!
Does anyone know how to define a circle (a face) in the input file. I have been able to define the basic shape of a semi-circle, but i am having difficulty with generating the nodes and elements.
Any help would be greatly appreciated
Thank You!





RE: Defining a circle
RE: Defining a circle
ultimately i would like to create a circular face with a mesh that converges in on the circle's centre.
Is this possible?
RE: Defining a circle
I would recommend working on 1/4 of the circle at a time by partitioning your circle with lines (i.e. from 9:00 to 3:00 and 12:00 to 6:00 in terms of a clock). Then you can apply a bias to the nodes along these lines so that there are more nodes near the center. Then mesh it...
RE: Defining a circle
I need to be able to define the circle in the input file as i want to perform a parametric study.
I cannot do this in CAE, as otherwise this comes up as co-ordinate data in the input file, which is far more difficult for me to parameterize.
Do you know how to define a circle in the input file?
RE: Defining a circle
You could probably do what you need to do with some Abaqus python scripting
RE: Defining a circle
Your right. I will be doin my parametric study using python scripting. However i am not completely sure of how i would apply the mesh using co-ordinates. If it's not too much trouble, would you be able to explain this, by applying this to my input file? (which i have attached).
Many thanks in advance
Jay
RE: Defining a circle
This example goes through all the steps of creating the model in CAE and parameterizing it. Once you run through that example, you'll have an idea about how to apply it to your model.
RE: Defining a circle
RE: Defining a circle
So yes, i am first creating a 'user-defined input file', and i am using various examples (such as section "8.3 Investigating the skew sensitivity of shell elements") to help me acheive this.
I then want to parameterize this input file using the built-in parameterizing function of Abaqus. I already know how to parameterize the input file. The problem however is that i don't no how to define a circular face (and its mesh) in the 'user-defined input file'.
I hope this makes it clear of what i am tryin to acheive
Regards
RE: Defining a circle
<node_start>, <node_finish>, <node_step>, <node_centre>
RE: Defining a circle
*NGEN, LINE=C, NSET=<node_centre>
<node_start>, <node_finish>, <node_step>, <node_centre>
RE: Defining a circle
However, my real problem is that i don't no how to generate the elements incrementally for the circle.
Do you know how i could go about this? I know how to do this for squares, but i just cant do it for the circle!!
Thanks again an advance!
RE: Defining a circle
Meshing a circle using Elgen and Ngen in the input file is very challenging (which you've already determined). I believe the only way to do it, is to tie a box inside the circle. The reason is that it's difficult to get the node numbering to work out for Elgen. Though somebody who is super tricky might get it to work (I was wrong before, so I might be wrong here!). There shouldn't be any issue with using a tie constraint. Attached is a quarter circle input file (and the new input file created with "abaqus j=temp parametercheck") which has the mesh density and radius parameterized. You could extrapolate this to a full circle with a bit more effort.
(An aside... If you don't want to do a tie, then you will likely have to use CAE and run your parameter study as in section 8.3 of the script users documentation. Note that this is very very very different (and much much more powerful) than the type of parameterization that you are trying to use which is outlined in "16.1.1 Scripting parametric studies" in the analysis documentation.... i.e. there are two ways to do parametric studies: 1) pure python with CAE, 2) input files with python (via psf file and *parameter in input file))
RE: Defining a circle
Do you by any chance have the original input file? (not parameterized).
The thing is that i actually want to perform a parametric study on a cylinder rather then on a circle? If i am able to make a circle from your quarter circle example, then is it possible to extrapolate this to create a user defined cylinder?
If so, then do you know how I would need to define this in the input file?
Thank you again for all your advice and help
RE: Defining a circle
Study how the pes file creates the mesh (you can import it in into CAE using the Import Model command, and then turn on node and element labels).
RE: Defining a circle
I want to try extruding the quarter circle to give a quarter cylinder. However, i'm having difficulty in doing this as i'm unsure on how i would do the node numbering. Do you have any tips on how i could do this?
RE: Defining a circle
*Ncopy, old set=face1_name, change number=20000, new set=face2_name, shift
<offset in x-dir>,<offset in y-dir>,<offset in z-dir>
This has created the end face offset from the first face, and the node numbers are 20001 to 20783. Now, use nfill to create the layers of nodes in between
*Nfill
face1_nset, face2_nset, 19, 1000
This will create 19 layers of nodes. The first is numbered 1001-1783, the second 2001-2783, etc.
(I guess you want a solid cylinder? for some reason i thought you wanted a tube when you wrote cylinder :) )
RE: Defining a circle
Yes that is correct, i am tryin to generate a cylinder. However, i want to generate a cylinder with a changing cross-sectional area. Do you have any advice on how i could do this?
RE: Defining a circle
RE: Defining a circle
RE: Defining a circle