Optimization design for bird strike resistance of blended-wing-body civil aircraft cabin doors

The Blended Wing Body (BWB) configuration in civil aviation represents a major leap in aerodynamic performance, achieved through the seamless integration of fuselage and wing structures—effectively breaking through the design constraints of conventional “tube-and-wing” aircraft. Yet, this architectural innovation brings new challenges: the flattened fuselage places cabin doors directly on the windward surface, increasing the risk of cabin depressurization following bird impacts. Current airworthiness regulations (e.g., CCAR-25.365) lack specific provisions regarding bird strike resistance for cabin doors, and thus, traditional protective strategies are not readily transferrable to BWB designs. To address this, a Finite Element (FE) model was constructed for the BWB cabin door, incorporating the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS). Upon validating its static strength under extreme loading conditions, a surrogate model was established, enabling multi objective optimization using Latin Hypercube Sampling (LHS) and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) algorithm. This optimization yielded a 23.27% mass reduction, with a 10.28% increase in the Tsai-Wu failure factor. Furthermore, a coupled Smoothed Particle Hydrodynamics-Finite Element Method (SPH-FEM) numerical approach was employed to simulate the bird strike scenario involving a 3.6 kg bird traveling at 140 m/s at an incidence angle of 18.43°. To bolster impact resistance, structural enhancements were introduced using 7075-T351 aluminum alloy doublers around the door and adjacent cutouts. These enhancements were further refined via a Multi-island Genetic Algorithm (GA), resulting in an additional 32.20% reduction in reinforcement mass. The post-optimization analysis confirmed the absence of perforation damage and plastic deformation in the door locking system and kinematic linkage. This research establishes a novel framework for assessing bird strike resilience in BWB cabin doors, contributing foundational data to airworthiness certification and offering practical reference for subsequent experimental validations.