I am very often getting the following error during an analysis when using e.g. the Mooney-Rivlin model:
ERROR: Vector length = NaN Vector= NaN NaN NaN Possibly bad normal vector or guiding vector direction. ERROR: Vector length = NaN Vector= NaN NaN NaN Possibly bad normal vector or guiding vector direction.
Does this mean that Algor is having trouble to calculate the shell elements' normal direction for the next iteration?
In this case, it will be helpful to use smaller time step. However, MES does not automatically reduce time step in this case, while it will crash.
One defect has been reported. And the fix will be added in the next new release (Autodesk Algor 2012): MES will reduce time step with message rather than crash in this case.
-Shoubing
The fix in Autodesk Algor 2012 has been done. The code will automatically reduce time step with outputing the follow message:
ERROR: Vector length = NaN Vector= NaN NaN NaN
Possibly bad normal vector or guiding vector direction.
** Time step reduction due to: bad normal vector or guiding vector direction
However, the user needs to make sure the guiding vector direction is correctly set.