Splitting surfaces in Sim Mech 2015 - latest options

[LukeDavenport]

Hi,

Quick question - am I right in thinking that the tool previously known as 'Surface Knitting' (with the ability to split faces inside Sim Mechanical) is no longer included, and the current options are the 'Virtual Imprinting' option and the 'Split Surfaces on Import' option only? I am simply looking to split a cylindrical bearing face (without using the CAD application) and cannot find the option.

Many thanks for your help.

Luke

[AstroJohnPE]

Hi Luke,

You are correct that "Surface Knitting" was renamed to "Surface Splitting" since that was more descriptive of the changes to the model that the user could see. (Who cares what the software does "behind the scenes" as long as it works, is fast, etc. ) But otherwise I do not remember ever having an option for the user to choose to split a surface or not. Perhaps you are referring to one of these features:

1. Prior to version 2013 (released March 2012), the software would split cylindrical surfaces. It may have been a requirement of the software used at that time, but there was no control for the user to activate or deactivate it. Also, there was no control over where the surface would be split. In version 2013, Autodesk software was used to import CAD geometry, and it did not require surfaces to be split.
2. There was (maybe still is) a way to create contact pairs when importing a CAD model. But that ability can take "a long time" in large assemblies, and most of the time it is not required to create individual contact pairs when most parts have the same type of contact (usually bonded). But users do have the option to select two (or more?) parts, right-click, and create all combinations of contact.

You always have the option to change the surface number of lines after meshing the model. This can bet a little confusing because you are really dealing with two different features (a 3D CAD surface versus a "surface" formed by element faces). Version 2014 made a change so that the CAD surfaces were visible instead of just the mesh surface. In some cases the CAD surface can partially obscure the mesh lines (depending on the curvature). I don't know if the surface selection is based on the CAD surface, the mesh lines, which one you click on, or if it doesn't matter. In case there is a priority, use the "View > Appearance > CAD Surfaces" to toggle the visibility of the CAD surfaces.

Also, if you have Autodesk Inventor Fusion, you can modify the "simulation" CAD model without changing the original CAD model. So, you could either split the surface physically, or insert a new part so that you can use "surface splitting" to cause the surface to be split. This concept is described on the page titled "Surface Splitting" in the Help documentation.

[LukeDavenport]

Hi AstroJohn many thanks for the reply. I am a little confused by your
comment 'You always have the option to change the surface number of lines
after meshing the model'. Are you simply referring to refining of the mesh?

So if I understand your reply correctly - if I wish to split a cylindrical
face to apply a bearing load the simplest option by far is to insert a CAD
part to force the spllitting. This is not ideal in the case that the user
does not have CAD on their system.

Thanks again.

[AstroJohnPE · Accepted solution]

Let me start by pointing out that for a bearing load ("Setup > Loads > Bearing"), the surface can be an entire cylinder or any portion! The software will only apply the load to the half in the direction that you specify, so there is no need to split the surface. Of course, if you are using a different type of load, it may be necessary to split the surface.

The option to change the surface numbers is done as follows:

1. Select the lines you want to change: "Selection > Select > Lines".
2. Change the surface number of the selected lines: "Draw > Modify > Attributes".

Note that there may be some commands that work only on original CAD geometry and may not work if the lines are changed manually. Commands such as "Draw > Design > Centroid Creator", "Setup > Constraints > Pin Constraint", and "Setup > Loads > Bearing" may be limited to original CAD geometry only -- I don't remember.

Also, the perimeter of the new surface may not be unform/straight since the region being changed is based on the randomness of the mesh.

[LukeDavenport]

Thanks AstroJohn, much appreciated!

Luke