How do you analyze a pressurized fuselage section with cutouts for windows and doors?

Pressurized fuselage analysis with cutouts involves: Basic cylinder analysis (hoop and longitudinal stress from pressure), Stress concentration at cutout edges (factors of 2-3 for round holes, higher for rectangular), Frame and stringer redistribution of discontinued skin loads, Local reinforcement (doubler) sizing to reduce peak stresses, Fatigue analysis at critical locations (cutout corners, fastener holes), and Damage tolerance (crack paths, residual strength). FEM captures complex stress fields; classical solutions provide initial sizing. Door surrounds require massive reinforcement due to large cutout size. Fail-safe design ensures skin cracks arrest at frames. Fuselage barrels are tested to 150% design pressure for certification.