Notice the stunning silence? I think this is an indication that SW Simulation may not be the best tool for the job. I've been reading back through the posts on this forum to familiarize myself a bit with Simulation before giving it a try. (We have one seat and have a seat of ANSYS that I've been using. Because ANSYS is not very designer-friendly, we are hoping to expand our usage of Simulation.) I noticed another post where a person analyzing stresses in a layered composite structure found that the Factor of Safety tool gave him nonsensical answers. I see a number of question involving composites going unanswered. I think this is an indication that SW hasn't put the effort into composite models that is needed to use it for serious design. It seems that this is a highly specialized, complex, emerging technology that may not be ready for a more general purpose tool like Simulation to make an entrance. I would love to be proved wrong.
Your options are:
1) Modle as beams: Get a laminate calculator and compute the material stiffness of each section of the beam, then add orthotropic - maybe isotropic might be sufficient by the sounds of it, material definition for each section, and apply to each section of beam. Divide up the beam into separate solids for each thickness change.
2)Model as shells: build a surface model with separate surfaces for each ply change, add materials to materails library, add laminate shell definitions.
The one caveat is the handling of directions - simulation doesn't handle non-orthoganl directions all that well. You can approximate directins by breaking hte surfaces up in to smaller patches and adding co-ordinate systems to each one to et a better approximation. This is not simulations sweet spot but you can probably get a ball park estiamte.
I would advise that you do some simple tests that you can compare against known data or other calculation methods and figure out the subteleties.