Coupled Internal Wing-Box Layout- and Composite Optimization via Parametric CAD Modeling and Lamination Parameters

Kurzfassung

Conventional preliminary wing design workflows typically follow a sequential approach. The shape and internal layout of the wing are fixed first, followed by structural optimization of local stiffness properties of composite materials based on predefined load cases. However, this decoupled strategy neglects the critical coupling effects between the internal structural layout and local stiffness distributions of composite materials, often yielding suboptimal weight performance. Existing frameworks for layout design primarily rely on topology optimization, bi-level approaches that separate layout and structural optimization, or formulations that assume fixed local stiffness. This work proposes an integrated, parametric CAD-based optimization framework that directly modifies the internal structural layout like ribs and spars through explicit geometric parameters while simultaneously optimizing structural composite design variables, including skin thicknesses and lamination parameters. The methodology is evaluated on an established rectangular wing box benchmark. Results demonstrate that co-optimizing the rib and spar layout together with skin thicknesses and lamination parameters increases the mass savings to 15.20\% compared with structural optimization using a fixed layout. Furthermore, configurations with variable directional stiffness yield internal layouts that differ from those obtained under fixed stiffness assumptions, highlighting the benefit of capturing layout and local stiffness coupling effects.