Surface Meshing Errors from Surface Model

[Anonymous]

To the community, 

I have a rather large model (200+ parts) that I have converted to a shell model using an external program (solid edge). I saved the file by .stp conversion, and opened in Simulation Mechanical. I am able to get 90% of the mesh generated by tweaking global and local mesh options. I have tried just about everything with all the settings to get the mesh 100% watertight/uniform, but I am finding some very strange issues.

I have been planning to use shell elements (assuming this is the equivalent to ANSYS Shell 181 element type) in a non-linear structural analysis. The model has a few solids in it, as I am analyzing a local bolt failure, and looking for strength improvement ideas. Using the bolt mesh generator in past analyses, I have found that when the mating parts are meshed as solids, it works much better. 

I have tried manually "filling in" areas where the CAD geometry is disappearing, but unsure if that will be a good solution. I was using the features in the "draw" tab, such as line creator, and the 3 and 4 point mesh found in the "mesh" tab. After drawing the mesh/lines in the proper parts/surfaces/layers, I can not define the element properties, so I assume these added meshes would adapt the part's defined properties that I drew them in. Is this a good proceedure for repairing these issues? 

I have tried re-importing as .x_t and .iges files, and running into the same errors, if not worse. .stp has always seemed to work the best for me. 

Additional notes:

As meshed in the images attached, I have added more and more refinement, much more than I think is needed, and likely encroaching on very long solve times. I'd prefer to use the bricks for the solid mesh, and used tets when I had difficulties. 

I am running Simulation Mechanical 2013 on Windows 64bit computer. 

I greatly appreciate any thoughts. I need to solve the watertight issues with the solid mesh, and repair the missing geometry in the surfaces. I would be glad to share files as needed to further diagnose. Thank you in advance. 

[Andrew.Sartorelli]

Hi jmaher3GZEM,

Do you have access to Simulation Mechanical 2016 or Simulation Mechanical 2017? We've introduced SimStudio Tools, which can do a lot of geometry pre-processing to prepare it for Simulation. It may be a better environment to simplify your geometry and it can find and fix problems that may exist in the model. In addition, in the 2017 release we've added a new surface mesher using a Delauney advancing front technique, which can be better that our previous mesher in some instances.

Please note that Simulation Mechanical 2013 is no longer an officially supported product, the oldest version of Simulation Mechanical that Autodesk supports at present is Simulation Mechanical 2014.

Regards,
Andrew