There are two main classifications of stiffened panel modeling techniques use in GFEMs (global finite element models). The first is a smeared model that, as the name implies, smears the stiffener into a single reference plane of shell elements (technique 1). See About Smeared Panels. The second model classification has the stiffeners discretely meshed with either shell and/or beam elements.
Discretely meshed models have several variations - as shown below using Nastran terminology. For all discrete modeling techniques, the skins are represented using shell elements. For hat panels, there are two methods to model technique 4. Technique 4a represents the entire bonded combo with 1 PCOMP property, while technique 4b represents the skin and attached flange as separate properties.
Stringer segment components are created based on the user selected techniques. The choice of technique will affect which cross-section variables can be optimized. See Discrete Modeling Techniques - Sizing Implications.
