Axysimmetric analysis - AUTOSPC
Hi,
I have to perform a linear static analyisis on an axisymmetric component. I meshed the section in the XZ plane using CTAXI elements and I applied PAXI property; the model is constrained at the bottom and I've manually written the PLOADX1 at the top, in order to simulate a traction force.
I want to evaluate the stress concetration in a particular region of the component, so I used different mesh sizes.
When I run the model, AUTOSPC locks the y translational motion (dof = 2) in some grids, because of error 2133: the grid x 'has no stiffness and is not constrained'.
I would kindly ask you some hints to fix the problem.
p.s. : I performed the check on the mesh (panel tools>check elem) and no error was found.
In order to check if the problem was related to the mesh, I kept the mesh, but I changed the element type in CTRIA, the property in PSHELL and I put FORCES instead of PLOADX1; when I run this analysis, autospc didn't added any spc. So, is the problem related to the axisymmetric elements / load?
Thank you so much for your help
Answers
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I tried, but the analysis can't start:
*** ERROR # 2133 ***
There are d.o.f.s that must be constrained, see the above table.
the number of d.o.f. = 1230 -
OK, I will check and update
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thank you so much!
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HI,
I tried with different constraints and alligning the normals, but I got a different error.
I will check the solution for this and will get back to you.
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Thank you very much, I look forward to hearing from you
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Hi Enrico,
I am experiencing an almost identical problem on a structure of mine. If there has been any improvement on the matter, please let me know, lost tons of time on it too.
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HI,
Can you try with CTRIAX6 elements instead of CTAXI?
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thank you for your kindness
I tried to run the input file you kindly sent to me, but I still have the same problem (2133)
I'm using Hyperworks 2017 Student edition
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OK. I will check and update you soon.
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Hi Prakash,
I saw your files, but I think that the model is not well constrained.
By the way, as I can see in the output file, AUTOSPC continues locking spc 2 and, as a consequence, there are wrong stress results in the h3d file.
I apologize for bothering you, but I do not know how can I solve this problem
Thank you
Enrico
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Without AUTOSPC the model is under constrained which is lacking stiffness in Y direction.
Please see the attached model file with is constrained in 3, 4 and 5.
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Thank you
However, I don't understand the local stress peaks inside the model, they are not phisical and non-negligible.
Is it possible that they are related to the autospc? How to solve the problem?
Thanks
Enrico
<?xml version="1.0" encoding="UTF-8"?>
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Hi Enrico,
I will check.
One way is to use traditional elements with symmetric boundary conditions.
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Thanks!
Aim of the study is to evaluate the stress concentration in the component visible in the figure. So, unfortunately I can't model the whole component (or one quarter only) with solid elements, because it would require too much grids
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Hi Enrico,
I have written to experts on the same and waiting for their feedback.
I will share details ASAP
You can run with second order elements but make sure the element type is CTAXI after converting to 2nd order elements and remove AUTOSPC
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Hi @Enrico
Just an update...
The issue is with CTAXI 1st order elements with which see stress singularity.
Our developers fixed it for 2017. 3 release.
Meanwhile you can use 2nd order elements instead.
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Hi Prakash,
I've another question about CTAXI elements. In my analyses, I have to use a non-linear material model.
However, when I run the simulation, in the .out file I read:
*** WARNING # 1916
Nonlinear material(s) defined, but no elements appropriate to use them.Could you help me, please?
Thanks,
Enrico
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