Ansys Workbench Cyclic Symmetry

[Maximina]

HiI have a multi-stage cyclic symmetry model in the workbench. I have performed the modal analysis in Ansys Mechanical, Workbench. Depending upon the HI I use for different stages I am getting some spurious mode shapes where the displacement at the interstage boundary is not continuous. So to check the continuity at the interstage boundary I have created a path at the interstage and plotted the displacement for both the stages individually at the interstage to check for continuity.

Now If I have many such modes it'll be very difficult to check for disp. continuity. So I am trying to develop a Python script to read the rst file and check for displacement continuity at the boundary.

To restrict the results to a single body you'll have to use a scoping where you scope only the elements/nodes of that body.

To map and plot results on a path you can refer to this example:

-plotting/04-plot_on_path.html#sphx-glr-examples-06-plotting-04-plot-on-path-py

Hi @Pernelle Marone-Hitz, thank you for your quick response.

I have a circular path in the Mechanical model. Is there any way I can use the same path in PyDPF? If so how can I get that path from the mechanical model to PyDPF? The circular path I have created using cylindrical coordinates in Mechanical. I have searched for the option by reading the rest file. But I could not find any way to capture that path.

The path defined in Mechanical is not written to the result file so will not be accessible in PyDPF.

I'm not sure it would be available in Mechanical itself either (where DPF can also be used but I'm sure you're already aware).

To define the path in PyDPF I would use the same method as shown in the example, but provide node coordinates matching a cylindrical distribution. There's not definition of CS per say in DPF, but if you have the nodes in a Cartesian CS you could convert them to a Cylindrical CS or vice-versa.

Mechanical supports cyclic symmetry analysis, and makes it easy to simulate Cyclic Symmetry via a symmetry branch outline at the Model level. More specifically, a user indicates the Low Boundary and the High Boundary for the Cyclic Region of interest. Analyses such as static structural and modal analysis can follow, with both of them performing the analysis as if an entire circular structure is present.

In the simplest cases, the Low Boundary and High Boundary for a Cyclic Region are selected on opposite side faces on one body. They can also be applied to opposite side faces on a multibody part as in the half-cylinders in the figure above. In DesignModeler, parts that do not touch can be declared to form a multibody part, with the result that they will aid in creating Symmetry branches for cyclic symmetry. This article explores some of the details.

Creation of Symmetry Cyclic Regions is aided by multibody parts, because a Low Boundary and High Boundary cannot both be chosen on completely independent bodies, even though face topologies and sizes on the Low and High Boundaries are identical. With multibody parts, as above, selections of Low and High Boundaries will work.

Because of the Cyclic Region, the mesh appearance on the Low Boundary and High Boundary faces will match, so that cyclic symmetry node degree of freedom coupling will work. In the above figure, a Cylindrical Coordinate System was created with its Z axis on the axis of the wheel in this model. Note independent meshing in the parts below.

During Cyclic Symmetry in Ansys Mechanical, sufficient boundary conditions should be applied. More specifically, to prevent free motion along the Z axis of the cylindrical coordinate system, and to prevent free rotation movement Y direction (theta) of the cylindrical coordinate system, in a static structural analysis. In a modal analysis, a user should consider what is suitable for constraint.

In a modal analysis, both Cyclic Mode and Harmonic Index have to be examined by a user. A sufficient number of modes and harmonic indices should be considered to completely fill a range of frequencies of interest. Workbench Mechanical expands the view of the results to suggest the presence of all sectors.

Workbench Mechanical can apply Symmetry Cyclic Region High and Low Boundaries to a sector made of many bodies, as long as bodies with faces on the low and high boundary sides are declared to be members of a multibody part. This works for bodies that do not share a common boundary. Once enough multibody parts have been created, matching faces on the low and high boundary sides can be selected for Cyclic symmetry Region definition.

Plots of results are automatically expanded to show a complete circle of sector images, permitting reviews that are easier to understand, and that confirm that parts are connecting properly. Recent versions of Ansys Workbench permit control of the number of sectors expanded, and offer some tolerance for imperfect matching of Low and High Boundary face shapes.

Hello to everyone! I'm trying to understand a problem that I have with the use of the cyclic symmetry. I modeled a very simple geometry and a applied the cyclic symmetry. I obtained also a good mesh using tetrahedrons method, but when I solve the model it gives me the following message: "An error occurred inside the solver module the mesh is corrupted. This could be due to the presence of a mesh connection or the objects in a body with cyclic". I really can't understand what is wrong. Can you please help me? The pictures of all the settings I put are attached. Thank you!

Thank you for the answer, but I already tried different type of mesh and the problem remains. Moreover, I can't obtain a good mesh with the Sweep method and the other ones as well, except for the tetrahedrons one.

With sweep method I have an error message from Ansys: "Mesher failed to mesh topological edges". Moreover I need cyclic symmetry in the model because I want to simulate in the end a quarter of a pipe subjected to an internal displacement or pressure. What do you mean for "simple symmetry"? In the symmetry module I have: Symmetry region, linear periodic and cyclic region. (I am new with Ansys software so every suggestions will be very appreciated!)

Open the geometry in SpaceClaim, go through the tools on the Repair tab. You should end up with a body with exactly 6 faces, 12 edges and 8 vertices. When you have that, you can get a clean Swept mesh.

I did it. I have a geometry with exactly 6 faces, 12 edges and 8 vertices. The swept mesh works (in the previous model as well) without the cyclic symmetry. The symmetry region works, so it gives me a result, but it is not that I want. I guess that I can't model 1/4 of the pipe if I use the symmetry region, but I need 1/2, isn't it? Thank you for your time.

I have a model static structural model, press fit. Using cyclic symmetry with 8 sectors. Is the Force reactiion the total force for all 8 sectors or do i need to multiply the output value x 8 sectors.

Please refer to Mechanical help > Reviewing results for cyclic symmetry in a static structural or static acoustic analysis. The results for force reaction probe is calculated for the full symmetry model.

I made a small breakout model and came to these conclusions:

For reaction forces (fixed etc) the model returns the total based on the # of sectors

For contact forces, the model only returns the load from 1 sector regardles of the display settings or # of sectors

I've just been assisting a colleague (who's new to Mechanica) to set up an analysis. This analysis lends itself to cyclic symmetry, albeit only two-fold. He's successfully split the surfaces (actually using volume regions I think) and created a cyclic symmetry constraint, which has correctly recognised a 180 angle.

However, when we run the analysis there is significant displacement into the symmetry 'plane', and it's all in one direction ('outwards' or 'plus material') rather than the 'S'-shape I'd consider acceptable for this constraint. It looks suspiciously as though it's not actually enforcing the constraint, or at least not as we want it.

Possibly relevant: this is a contact assembly with two components and several volume regions on each, underneath the contact location in 'onion layers'. He's selected all the relevant surfaces for each half of the symmetry constraint, and there are no obvious discontinuities in the stresses which would suggest a missed surface.

I may be wrong from what I can see in the model you shared, but it looks like you have applied a cyclic symmetry constraint incorrectly. The help inside Creo Simulate does not seem to provide images of examples, but a Google of the subject might help. PTC's University does have a good reference video if you have access:

Cyclic symmetry is used to analyze repeated sections of a revolved part that has deformation occuring out-of-plane from each cut, but in an identically deformed shape. The slender cylinder that is cut does not look like it would repeat itself properly using the axis that was selected - the loading is not creating the same amount of strain energy on each split section. Am I missing something from the complete model that is not shown? Also, it is unusual for Simulate to allow an axis of revolution along a common element edge from each "side" of the symmetry cut planes.

I've used cyclic symmetry plenty of times before and I hope I have a good understanding of what it does - why do you say this is applied incorrectly? The model and loading has two-fold rotational symmetry as far as I can see.

The axis of revolution along a common edge shouldn't be a problem - in principle this is no different to analysing a 'wedge' of a solid shaft, except that in that case there would be no need to explicitly specify the axis, as Mechanica would infer it from the two selected 'sides'.

I hadn't spotted that the surfaces weren't identical - I thought they should have been, but as mentioned it isn't my model. Per my reply above I also found meshing errors, but for some reason it meshed happily when the cyclic symmetry was suppressed.

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