"Distorted element" message while analysis in Robot Structural Analysis

Autodesk Support

Apr 19, 2024

Products and versions covered

Issue:

"distorted element!"  message appears during shell model calculation in Robot Structural Analysis.

 

Distorted element
 

Causes:

Possible causes:

  • Too big user tolerance defined for Calculation model generation.

 

  • Not precisely defined panels geometry.

Some meshes of generated mesh are incoherent / damaged (overlapped, twisted, out of FE panel plane), probably caused by not precisely defined panels geometry.

  • Incorrectly defined finite elements not associated with defined panels exist in the model

Mesh is generated over incorrectly defined finite elements. Program tries to connect generated mesh with incorrectly defined finite element nodes.  After mesh deleting for whole model, finite elements not associated with panels remains in the structure 

Example:
finite elements generates on panel segment

 

Solution:

Possible solutions:

Increase tolerance for Calculation model generation.
 

  1. Open Analysis > Analysis types.
  2. Open Structure Model tab.
  3. Decrease User tolerance for calculation model generation.
  4. Calculate model.
Model generation

 

Deactivate Regular mesh in meshing options and remesh model before calculations.

  1. Select all panels.
  2. Open Analysis > Meshing > "Meshing options".
  3. Open Advanced Options.
  4. Set Delaunay mesh type.
  5. Switch off Regular mesh.
  6. Set required element size.
  7. OK.
mashing parameters
  1. Select all panels.
  2. Run Analysis > Meshing > "Local mesh generation".
  3. Calculate model.

 

For not precisely defined models, follow one or more of the suggestions below:

  • Find where distorted meshes are located (highlight distorted element with selection tool using its number).
  • Identify panels with distorted finite element.
  • If there are "incoherent mesh on edges" warnings, they will help to find which panels are meshed incorrectly.
  • Generate mesh for involved panels with changed meshing properties (change mesh size and/or switch off regular mesh option in Mesh parameters dialog).
  • If necessary, correct involved panels geometry.

 

Delete finite elements and nodes not associated with panels, then mesh model again.

Follow the steps:
  1. Select all panels (Ctrl+ A).
  2. Run Analysis > Meshing > "Local Mesh Deleting".
  3. Open Edit > Select.
  4. Choose Finite element selection.
  5. Choose Unassigned.
  6. Select finite elements by "^^" button.
objects selection
  1. Choose Node selection.
  2. In Attributes section choose Finite elements.
  3. Select nodes connected to selected finite elements by "^^" button.
nodes selection
  1. Close selection dialog.
  2. Delete selected objects by pressing Delete key from keyboard.
  3. Select all panels.
  4. Open Analysis > Meshing > Meshing Options > "Advanced options".
  5. Change Meshing method to Delaunay.
  6. Check off Regular Mesh option.
  7. OK.
meshing options
  1. Mesh model with Analysis > Meshing > "Local mesh generation".
 

Products:

Robot Structural Analysis Products;

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