quad elements posing as triangles
quad elements posing as triangles
(OP)
It's well known that 2D linear triangular elements are useless for stress analysis. If a model is meshed with triangular shaped elements but these elements are in fact quadrilateral elements with 2 nodes the same, ie. node numbers 1-2-3-3, will the reults obtained be just as useless?
corus





RE: quad elements posing as triangles
The results will be even more useless (if that's possible), triangles and quadrilaterals use different shape functions, thus a quad with a degenerate side is not the same as a triangle element, at least the linear triangle will generate some form of results, whilst the quad (if the solver doesn't kick it out) will produce rubbish.
RE: quad elements posing as triangles
Do you talk about the fact that there is no continuity of the second derivatives , i.e., the stress field for linear triangular element, plus some stresses that cannot been accessed, despite mesh refinement ?
RE: quad elements posing as triangles
I am sorry for this late reply & I hope your question is answered, but when this has occured in any of my analysis an element check will locate these elements &/or the analysis will fail with a message hinting (solver messages are never direct) the problem. I use FEMAP & CAEFEM currently, but NASTRAN & Patran have also notified me of these conditions.
JXC
RE: quad elements posing as triangles