What are best practices for FEM modeling of aircraft structures?

Aircraft FEM modeling best practices include: Global model for overall load distribution using coarse mesh beam/shell elements (GSM), Detailed models for stress recovery in critical areas with fine mesh and proper boundary conditions from global model; Correct element selection (shells for skins, beams for stringers, solid for fittings); Fastener modeling (CBUSH, spring elements, or MPCs); Mesh convergence studies for stress accuracy; Load application matching actual load paths; Model validation through known solutions, ground tests, and hand calculations; and Documentation per company standards. QA checks verify mass, stiffness, and internal loads equilibrium. NASTRAN, Abaqus, and ANSYS are common tools with certification-approved methods.