Corner Stresses 1

[biomedman]

When modelling corners in FEA, how can you check if the calculated von mises stresses there are accurate? Currently,
1)i look at the strain enrgy error for the entire model, and make sure it is < 10%
2)Check if applied force/moment is equal and opposite to the reaction moment/force

Whats' a goodway to check the accuracy?

Regards,
Ravi

 

[idly123]

Well accuracy has to be indirectly checked
1) Plot a graph of Log of error to the size of elements at each refinement level.
2) Estmate the effectivity index of the estimator at each refinement level for every element at the region of stress concentration
3) 10% permissible error is too high a valuew u can look for 3% -5%
regards
Raj

 

[corus]

Sharp corners have, of course, infinite stresses and thus successive refinements of the model will never truly calculate the stress there.

In general the model will produce forces and moments that are equal and opposite throughout. The total reaction forces can be checked against the total force you input to the model, however.

For stresses in general, I would look at the difference between the element nodal values at each node. For a good mesh the element nodal values should be approximately the same at each node, or within 10% say.