Show membrane only from Von Mises
Show membrane only from Von Mises
(OP)
I have a question on how to extract membrane only stresses. Please correct me if any statements I make are incorrect. I'm using I-DEAS NX5 and occasionally NASTRAN from an I-DEAS .dat export. The element I'm using is a thin-shell to represent typically angles and plates less than 1". In I-DEAS, when I post-process Von Mises stress, I get "top" and "bottom" surface stresses. It is my understanding that this is considered "Membrane+Bending" stress. I want to also view "Membrane only" stress, which I believe is the stress at the neutral axis of the section. It is my understanding that the "middle" surface in I-DEAS is just (top+bottom)/2 or the average, but this is not what I'm trying to extract.
To sum things up, in I-DEAS how would you extract "Membrane only" stresses using Von Mises stress display for a thin shell element.
Thanks
To sum things up, in I-DEAS how would you extract "Membrane only" stresses using Von Mises stress display for a thin shell element.
Thanks





RE: Show membrane only from Von Mises
"It is my understanding that the "middle" surface in I-DEAS is just (top+bottom)/2 or the average, but this is not what I'm trying to extract."
Are you saying that IDEAS has the option to use the "middle" surface, but that you don't believe it would be correct? If the N.A. was at the mid-surface of the shell, then the formula you provided would work.
Brian
www.espcomposites.com
RE: Show membrane only from Von Mises
RE: Show membrane only from Von Mises
But I would have thought it would first average the raw stress components and then create a Von Mises stress. For example, if it is pure bending, you would have compression on one side and tension on the other. The provided equation would cancel these out and leave you with a zero stress, as expected. The same approach could be said for the pure axial load or other cases.
Does IDEAS do it this way or the other way (i.e do you have some test case results)? I have no way of checking IDEAS, but it would seem odd (to me at least) if it is actually doing what you are saying.
Brian
www.espcomposites.com
RE: Show membrane only from Von Mises
RE: Show membrane only from Von Mises
RE: Show membrane only from Von Mises
Don't know if you can do that with Ideas.
tg
RE: Show membrane only from Von Mises