Modeling Substructures and Submodeling using Breakout Models in Femap

[@StructuralDesignAnalysisInc]

Want to try the demonstrations for yourself? Download the Step-by-Step walkthroughs: structures.aero/blog/submodels-breakout-models-fea/#walkthrough

[@pauk4272]

Regarding the wing rib example: you applied displacements from the wing model as a load to the periphery nodes of the rib. You also applied pinned constraints to the same set of nodes. My understanding is that those constraints are zero displacements (translations). What is the point of applying the displacements to nodes if you will constrain them after that? How did you even get any results after running such model? I can see all working fine if you applied what is called "stability constraints" that would be constraints (zero displacements) to just few nodes to prevent rigid body motions which also would not prevent applied displacement being enforced.

[@outrigr]

It should be noted that for demonstration purposes this is OK. In an actual problem the large "Global" FEM of the wing structure should have an, albeit crude, idealization of the Rib Cutout. The simplified cutout in the global model will change (maybe not much) the localized stiffness of the rib with cutout. The Global model should then be rerun with the simplified cutout to obtain an updated set of deflection boundary conditions around the Rib with cutout. Then the results of the detailed Localized rib with cutout will be more accurate.

[@StructuralDesignAnalysisInc]

That's a good point. Small updates to a piece of the FEM can ripple changes to the Global FEM. Users should use their engineering judgment to decide if their specific situation warrants a re-run of the entire FEM.

[@captainvlog]

wow. I didnt even know some of those features existed

[@pauk4272]

Another question is if there is a way to apply translations and rotations (all at once) to periphery nodes within one load set?

[@engmike2024]

GOSTOSO