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Mesh has always been the black art of analysis. The importance of generating a good mesh for result convergence; cannot be emphasized enough. Here are some tips towards improving results generated, as a result of changes to geometry.
Line contact
While analyzing geometry with line contact, (e.g. cylinder on flat plane) the results across the line are essentially meaningless. Why so? Stress is calculated using force/area, the area along a line contact is zero, hence the stress generated is essentially infinite. I doubt there is a single mathematical tool, that can understand infinity. So, its wise to convert the line contact to surface contact by defining a small cut in that region. This cut being small approximates our geometry to a certain extent, but since its small, geometry should meet the design intent.
 
Surface contact Line contact
Point Contact
When two cylindrical or spherical surfaces come in contact, the contact is essentially a point. The problems we face in a point contact is the same as the one in line contacts. It is imperative we avoid, such contacts to generate reasonable results.
 
Point contact Surface contact
Note: The suggestions made in line / point contact are for linear static analysis. There are other techniques to handle line / point contact in non linear analysis.
Sliver Faces / Cut faces
Sliver faces and short edges are the most common cause of meshing problems. Sliver faces must be avoided as that would lead to mesh failure and hence no effective analysis can be run on that part. Besides one must be careful while creating geometric features. Some operations unintentionally lead to cut faces, sharp corners, or extremely small thickness. The mesher must respect all edges so surface dimensions much smaller than nominal element size may cause distorted elements.
 
Sliver faces Cut faces
In assemblies, the placement of parts with respect to each other may lead to distortion of elements in the mesh being generated. If such cases are unavoidable, it is advisable to use “incompatible mesh” under the contact options.
 
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