Element Deletion

Hello,

i simulate a three-point-bending crash test of a FRP. Therfore i use 1 solid element over the thickness, a thick-shell property (22) and the material law 25. In the material law 25 i use the energy failure criteria with the element-deletion flag Ioff=2 and a specific Wpmax.

Unfortunately, when the energy failure criteria is reach, the element is not deleted but the stress is set to zero and hourglassing is beginning.

How do i let the elements be deleted if the failure criteria is reached?

Thank you very much!

Tim

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Simon Križnik

Hi,

for most physical behavior try with Ioff=5 or 6, as suggested in RADIOSS theory manual and on page 65 of:

http://publications.lib.chalmers.se/records/fulltext/199981/199981.pdf

mrtimwinkler

Hello and thank you very much for your answer!

The problem is not that the failure criteria is not reached (i have tried all of the Ioff choices with very low failure criteri limits) but that the element is not been deleted. The stress is always set to zero but the element is not been deleted. Is this a problem of the element type or property? In the same model with shell elements the elements are deleted. In the reference guide they say the deletion is posible for shell elements and thick shell elements and my model is made of thick shell elements.

Simon Križnik

If the same model is able to run with shell elements then either:

-there is some issue with property parameters

-thick shell elements are not supported for deletion

Thick shells are used only when thickness to length ratio is between solid and thin shell recommended range:

When h/L is large, shear deformation is at its maximum importance and the user should use solid elements. When h/L is small, transverse shear deformation is not important and thin shell elements are the most effective choice.

Altair Forum User

Hi,

As far as I remember the element deletion will happen only for conventional shell elements. For other element types the deviatoric stress will be set to 0 once the element reaches the failure criteria.

Best Regards,