Design-Oriented Assessment of Composite Aircraft Panels under Multiple Loading Conditions

Composite aircraft panels play a critical role in the structural efficiency of modern airframes, particularly during early design stages where laminate selection decisions have long-term implications. While stiffness requirements are typically evaluated under individual load cases, aircraft panels are in practice subjected to combined mechanical and thermal loads, making single-load assessments insufficient for informed structural design decisions.

In this work, a design-oriented numerical study is presented to evaluate the stiffness response of a flat composite aircraft panel under multiple representative loading conditions, including in-plane compression, transverse pressure and uniform thermal loading. A set of symmetric laminate layups commonly employed in aerospace structures is examined using finite element analysis (FEA). For each load case, displacement-based stiffness metrics are formulated using normalized reference quantities, enabling consistent comparison between different layup configurations independently of the applied load magnitudes.

The individual stiffness responses are subsequently combined within a multi-objective framework to identify trade-offs between competing structural requirements. Pareto fronts are constructed to highlight laminate configurations that offer balanced stiffness performance across multiple loading scenarios, supporting rational layup selection from an aircraft structural design perspective. The results indicate that laminate designs optimised for a dominant load case may exhibit unfavourable behaviour when assessed under combined loading, underscoring the importance of multi-load considerations at the preliminary design stage.

The proposed approach provides a transparent and computationally efficient methodology for comparative assessment of composite aircraft panels and is well-suited for early structural design studies. The framework can be readily extended to more complex configurations, such as stiffened panels or coupled buckling analyses, in future work.