Reduce your Mesh Time
File: PVE-4061
Last Updated: Jan 1 2010
LB
Sometimes mesh times can be much longer than solve times. Why?
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Mesh Tolerance Settings
File: PVE-4048
Last Updated: FEb 17 2010
Laurence Brundrett
What impact does the mesh tolerance option have on the mesh?
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Mesh Refinement
File: NA
Last Updated: Nov. 26, 2008
LB
Using the Error Function Results for Areas At Discontinuities
Summary:
Error plots show how well the complexity of a mesh matches the complexity of the model. Once the mesh matches the complexity of the model, the reported error is low. We use 5% error as an acceptance criterion. This method checks the whole model at once, and is much less work than mesh refinement.
This study compares mesh refinement at a node with error plot methods to estimate the convergence of FEA results. CosmosDesigner 2708 SP5.0 FEA software is used for this report.
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Mesh Refinements Near Discontinuities
File: NA
Last Updated:
LB
Summary
Error plots show how well the complexity of a mesh matches the complexity of the model. Once the mesh matches the complexity of the model, the reported error is low. As a guideline, Pressure Vessel Engineering uses 5% error as an acceptance criterion.
This report examines the accuracy of stress results near an area of discontinuity as the mesh is refined. The 5% error criteria estimates the errors in the mesh except in areas of very low stress located near high stress areas. These areas are not usually of interest in a pressure vessel study.
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Why Use 2nd Order Integration Elements?
File: NA
Last Updated:
LB
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Summary
This is part of a series of articles that examines the ABSA (Alberta Boilers Safety Association) requirements on writing FEA reports. These guidelines can be found at: ABSA Requirements. The use of 2nd or higher order elements is one of the requirements.
Pressure Vessel Engineering uses CosmosWorks for Finite Element Analysis. It is expected that these results would also be applicable to other FEA programs.
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Surface Model Mesh Challenges
File: PVE-4048
Last Updated: Feb. 24, 2010
LB
Surface models can be challenging to mesh. Parts that touch might not share nodes preventing the correct transfer of loads. The resulting calculated stresses and displacements can be wrong.
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Easier Surfaces
File: PVE-4048
Last Updated: Feb. 24, 2010
LB
Surfaces can be challenging to create, but solids are easy to convert into surfaces. Surfaces originally created as solids do not have the problem of nodes not joining at edges (previous topic)...
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Solid Model Mesh Challenges
File: PVE
Last Updated: May 2010
LB
Sometimes a multibody model refuses to mesh with the standard mesher. Regardless of the element size and tolerances used, some parts refuse to bond.
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Solution for Long Mesh Time of Shells
File: PVE-4048
Last Updated: June 2010
CM
When meshing shells, the mesh gets up to 99% and then hangs for a very long time sometimes for hours depending on the mesh size. The mesher is going through some type of crazy routine trying to orient all of the shell faces in the same direction. We can do this manually in a few seconds by picking the face and then right clicking mesh and "Flip Shell Elements".
Go to Simulation options and un-check the "Automatic re-alignment for non-composite shells":
In the example model, doing this reduced the mesh time from 8 min 21 seconds down to 20 seconds.
Adjusting the mesh size after setting the face orientation causes some of the faces to be re-oriented. Manually flipping the faces is still much quicker than waiting for the automatic re-alignment.
