Hello,

That's the first time I connect to your site (although I've been a Nafems
member for 1 year!),
and I have indeed a particular question about static failure.
We are studying the opportunity to modelise our structures (landing gears)
using shell elements.
The point is that we have always use beam elements and a classical strength
analysis to calculate
margins, including bending/torsion modulus of ruptures.
The material we use is a very classical one (isotropic and homogeneous).
With shells (and unlike beams), the basic results for the calculation of
margins of safety are stress and strain.
In limit condition, we use both a VonMises criteria or max stress/max shear,
and it works properly.
The question is : what can we use in ultimate condition, when yield stress
is greatly exceeded?

Any element of answer would be appreciated. I've indeed try to search
ultimate criterias in the litterature
but did not really succeed. I remain available for any further
clarification.

Best regards

Florian SEROUART
Analysis methods

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