Today’s blog post will treat geometry idealization using idealized part files, as well as the Promote and WAVE-link operations to increase the simulation model redundancy. I will show a workflow which can increase the redundancy in your simulation model if you need to perform changes to the geometry, or exchange the geometry entirely for a new revision, when you have already set up your simulation by using idealized part files with the Promote, WAVE-link, and Replace Component commands.
Using idealized parts
Let’s begin with an overview of the workflow we intend to create:
The image above shows a generic overview of a simulation assembly using Simcenter 3D where all geometry is originally contained in the A.prt master geometry. In the flowchart it is also clear that the master geometry in A.prt is not directly associated with the structuralPart.fem file where the mesh is defined. Instead A.prt is referenced in the structuralPart_i.prt idealized part which also can be applying Promote or WAVE-link operations on the master geometry (more on that later). Thereafter, the .fem file reference the idealized part file to obtain a description of the geometry to mesh, and finally the structuralSim.sim file reference the .fem file to have a mesh and a geometry to define the solution upon.
Before digging deeper into the subject, it will be good to recognize the difference between what in Simcenter 3D is referred to as Geometry idealization and Geometry abstraction. Idealization, fittingly performed in the idealized part, is to make changes to the geometry already at the part level e.g. by removing holes, fillets, or faces etc., which are not interesting in the analysis. Geometry abstraction is instead performed in the .fem file where faces, or edges, can be split for boundary condition application, or where small geometry features can be ignored to improve mesh quality. In this post, geometry idealization will be in focus of these two.
In Simcenter 3D when a new .fem from .prt is created, users will be prompted with the option of creating an idealized part file (if the associated part is not already an idealized part). This structure enables the user to reference the master geometry in A.prt and take part in updates made to it, which can be made optional as we will see, while changes made in the idealized part will not be communicated back into the master geometry.
Sometimes the user would even be required to work with an idealized part instead of working directly with the master geometry. For instance, if the geometry is checked out from a database where the user does not have write access.
Even though it is not always required, my recommendation is to work using idealized parts as it will inherently keep original CAD geometry for comparison. It also enables the use of Geometry Preparation → More → Edit and Defeature commands. Additionally, you create a well-defined structure were different simulations, demanding varying levels of idealization, can use the same master geometry. It will just be the idealized part files which will be altered.
Creating an idealized part file can also be done via the Pre/Post module when having a regular part file open. From the newly created idealized part file a .fem can be defined from, or associated to it, as well.
Setting up the .fem and .sim file
To showcase the benefit of using the idealized part file let’s set up a new structural simulation. In the image below an idealized part has been created from the master geometry A.prt. Then a mesh has been generated, and finally boundary conditions with fixed constraints and force loads have been defined on polygon faces of the polygon body from the idealized part. The option of defining boundary conditions on polygon geometry will be important in the following steps.
Imagine we at this stage realized that the mesh generated contains too much detail. What if we want to perform geometry idealizations? One option to remove unnecessary details would be to use the Synchronous Modeling → Delete function in the Pre/Post application, but we must do one thing first…
If you have an idealized part and want to add or remove features in it, but instead become frustratingly aware of your inability to do so: then it is very likely that you have forgot to Promote or WAVE-link the part. You will find these commands under the Pre/Post Home tab.
Before a Promote or WAVE-link operation has been performed you will not be allowed to perform changes to the idealized part. A way of explaining this is that the idealized part can be seen as an assembly which includes the master geometry as a component. With this hierarchy you are not allowed to make changes to the parts of the assembly which are not on the assembly level. However, when using either of these commands an associative copy of the master geometry is brought to the level of the assembly, enabling you to edit the geometry.
There are some differences which sets these commands apart. Using Promote you are confined to work with solid or sheet bodies, and you must be able to load the master geometry, otherwise the idealized part will not be visible either. This is due to Promote continuously relying on the master geometry for the definition of the idealized part as Promote creates more of a reference to the master geometry. This also means that any changes made to the master geometry will be passed on to the idealized part. However, when setting up simulations, usually you are working with revisions of parts and problems with concurring geometry updates during setup is perhaps not an issue. Moreover, using Promote is rather straightforward, and after a while it will be routine when wanting to edit an idealized part.
Using WAVE-link you can link many different types of geometry objects besides solids and sheet bodies (lines, points, planes, etc.). Moreover, you do not have to be able to load the master geometry to visualize the part as the WAVE-link creates a copy of the master geometry in the idealized part file, which also enables you to control whether you want to infer updates from the master geometry into your idealized part file or not. (Via the Customer Defaults → Assemblies → General → Interpart Modeling → Delay Link Update checkbox)
A caveat using WAVE-link is that you will create a copy of the master geometry in the idealized part file. That is, you will have 2 identical geometries in your part file and if you do not take care, it is easy to start defining some entities in your model on the master geometry and other entities on the WAVE-linked copy. One easy way to avoid this is to check the Hide Original checkbox upon WAVE-linking seen below.
My recommendation is to use Promote every time you can, as you can always convert a Promote operation to a WAVE-link, but not the other way around. Some features, besides the above written differences, such as the Replacement Assistant (when the master geometry needs to be swapped) can only be used with WAVE-linking. However, for many use cases Promote is providing enough functionality and is easier to use.
By using the Synchronous Modeling → Delete function in the Pre/Post application and removing the superfluous details of the small fillets, some chamfers and the bosses on the bracket neck, these updates are forwarded from the idealized part to the associated .fem and finally also to the .sim file. In the video below you can see how these features are removed and how the mesh and simulation model are updated because of this. The loads and constraints, as well as the mesh controls, are all updated as they are defined on polygon geometry.
Replacing Geometry
Now for a final “What if?”: Let’s say the first revision of the A.prt was analyzed and we obtained a second revision with some changes. We want to perform the same analysis once again, but with the new geometry as in the image below:
Using the workflow described above, we can replace the reference to the master geometry in the idealized part file using the Replace Component… command in the Modeling application for the idealized part file. Meaning that all idealizations (removal of unnecessary details and changes made to surfaces) are re-applied to the new master geometry reference. Moreover, the mesh definitions can be updated in the .fem file, and boundary conditions are also re-applied as they are defined on polygon faces.
This is shown in the video below where the A.prt reference in the idealized part file is replaced with a reference to its second revision. After the replacement, the mesh is updated and all boundary conditions in the .sim file are retained.
Key take-homes from this post are that:
- using idealized parts as geometry reference in .fem files is recommended and sometimes necessary to perform geometry idealizations
- applying boundary conditions to polygon geometry (faces, points etc.) will enable them to be redefined upon remeshing
- either Promote or WAVE-link is required to make changes to idealized part files’ geometry
- Promote is recommended to use whenever possible: for more advanced use-cases WAVE-link may be necessary, but all Promote operations can be switched into WAVE-links
Hope this post has been useful for you and that it will bring some extra redundancy to your simulation models.
Viktor Hultgren, M.Sc.
Contact: support@volupe.com
+46 704 21 06 61
