Warning G3009: elemtype ELEMENT id HAS SINGULAR GEOMETRY in Nastran

Autodesk Support

Oct 8, 2023

Products and versions covered

Issue:

The analysis gives many warnings about singular geometry in Nastran.

Causes:

Distorted elements.

Solution:

Remesh the model and/or clean up the geometry.

See Also:

A common situation is a pin or shaft that passes through a hole. If the mesh on the pin is much finer than the hole, then an interference can occur mathematically. (This is true even if there is a clearance gap between the parts in the CAD model.) The contact tries to eliminate the initial interference by moving the nodes on the pin, and this can create distorted elements.
 
A pin in a holeSome mesh lines on a pin are shown in yellow. The mesh on the part with a hole are shown in dark black. Because of the size difference, the pin now interferes with the 8-sided hole.
Using a mesh size on the pin and around the hole that are comparable in size may eliminate the warning.

If using an interface that provides access to the Nastran parameters (such as In-CAD), setting the parameter NCONTACTGEOMITER to 0 will prevent the solver from moving the nodes on the pin. However, this will also keep the initial interference in the analysis which may cause stress at the pin-to-hole interface.

See Also How to resolve FATAL ERROR E5000 in Nastran Analysis.

 

Products:

Fusion; Nastran; Inventor Nastran;

Versions:

all;

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