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hi, i´ve been struggling for a few days trying to understand why does pv elite and Compress (using the formula given by Moss, see the image below) take into account the reaction on the saddle due to transversal wind load when computing bending momentes that act on the vessel. i looked this...

rb1957 - the last pic shows only the solid part. what you are seeing are solid elements, the shells are out of the pic

i don´t understand, shouldn´t every case be evaluated independently by a mesh convergence study? i did that and this maesh was the result. how can there be a "general rule" for all the cases that three quadratic elements are sufficient? it depends on the stress and strains gradients

six quadratic elements through thickness. but i also have tetrahedral elements where hexaedrals where impossible...

that would be ideal, problem is, it´s impossible to use only hexahedrals because of geometry coplexity. and modeling everithing with solids requires a ridiculous amount of RAM (i have 128 GB and i couldn´t do it), hence my mixed shell/solid approach...

TGS4 - let´s use another approach. how would you model the structure if you had to do it from scratch?

yes, i´ve tried with different mesh sizes relative to each other in sample problems and it keeps happening... all nodes on the 3D face are connected to some of the nodes on the 2D edge, that is what the program does.

80, give or take, why? the problem is not in cyclic loading but in plastic collapse evaluation. it´s only a numerical problem.

karachun - the whole vessel undergoes plastic strains, since ASME VIII div. 2 part 5 requires to evaluate the structure for 3.5 times the design loads... i´ve tried your approach and it works, but naturally, the structure is virtually stiffer in that area giving erroneus results within the...

that´s correct, they are local, however the problem is that the simulation diesn´t converge due to plastic instability... with elastic material works fine and the reuslts are correct. the problem is with the plastic material

rb1957 - that´s exactly what i did and said before that with elastoplastic material the RBE elements generate unreal plastic strains tha make the simulation fail to coverge... please see the image in my first post

thanks for your reponse, but the model is not symmetric for two reasons, 1- the loads applied on the nozzles are not symmetryc 2- this is a simple model i draw to illustrate my point, but the real geometry is much more complex... regarding submodeling, it has two problems, 1- as i said...

hi, every time i model a nozzle connection i come across the same problem: " how much shell to model". i have tried many options but none of them quite satisfies me. if i model the whole circumference of the sheell with solid elements, it takes a lot of elements and thus, a great computational...

i know, but what about the nodal fraction? shouldn´t one expect a smoother transition between elements?

i have that too: X axis is 1/volume of elements , and de y axis is de strain normalized being 1 the value of the coarser mesh. however i showed the other plot since it is "more alarming" than this one.

TGS4, this is not an issue with a failure mode, rather it is a numerical issue. in order to affirm that the results are not mesh dependent, i am performing successive refinements and compare the results. this is the model: this is the nodal fraction (ansys plot) that measures the percentage...

TGS4 - i achieve convergence with respect to static equilibrium. i implemented the curve from appendix 3-D following the steps specified there. a multilinear curve. i´m using 20 nodes bricks where i can and quadratic tetrahedrons where the geometry does not allow bricks for it´s complexity.

your right, sorry, i meant section VIII (8)

i mentioned it, ASME XIII div 2. nevertheless, it is independent of the code, it´s a Finite elements analysis problem

Div 2