Load Case Combination

[SmoothGear]

Hi people, I'm new to MAPDL and having some trouble setting the boundary conditions for a model.
You see, I'm trying to simulate a panel that's subjected to shear flow, and two different axial loads. The problem is that I can't seem to make them work together. I was trying to apply reactive forces but still MAPDL tells me there are nodes that would give a negative equation (something like that)even with added constraints, and after searching in the help manual I came across with this concept: "Load case combination".


So, my questions are:
what is it for and would it be of use to me?, does anyone know if there's a way to achieve what I'm trying to do?

Thanks!

PS:
I'm leaving an Image to depict what is the load case I'm trying to recreate:

 

[rickfischer51]

Load case combination is for combining results from two or more sets of results. I dont think that's what you want.

Does your model contain solid, shell or plane elements?

It's not clear to me what you are trying to do. Your reference to shear flow suggests your are applying torsion to an open section. I dont know what sigma_r=sigma_y=cte (coefficient of thermal expansion?) means except that you probably have a thermal load. You seem to want to apply stresses as opposed to the usual method of applying forces, deflections, temps, etc. Without knowing more, I would suggest modelling this with solid elements, then use SURF154 elements to apply your stresses. Note that with SURF154 elements you can apply pressures normal and tangiential to the surface. Apply the SURF154 elements to any surface to which you will apply a stress. Use the ESURF command to do this. Then apply your stresses as pressures with the SFE command

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[rb1957]

i don't know "MAPDL" ... but you could apply that loading as a single load case, or combine three cases.

Quando Omni Flunkus Moritati

 

[SmoothGear]

Thanks for your responses.

rickfischer51, sorry haha, I was vage on my description. Actually this is just an isolated case where I'm trying to reproduce the stresses in this panel due to a shear flow (the panel forms part of a closed cross section) and other loads, like pressurizing and bending moment (it's a fuselage what I'm analyzing). sigma_r and sigma_y stand for radial stresses originated by the pressure load inside the cabin.And i'm not considering thermal gradients.

I hope this helped a little, for now I'm gonna check the element SURF154 and see if it suits me.

Thanks again!