Preliminary Structural Design Tool for Flexible Slender Bodies with Aeroelastic Constraints

Slender aerospace vehicles, such as missiles and rockets, are inherently flexible and therefore deform under aerodynamic loading. With new, advanced light-weight materials, modern designs are becoming increasingly more flexible, making aeroelastic effects a critical factor in performance and stability. For slender bodies, aerodynamic forces can bend the vehicle into a characteristic “smiling” shape, shifting the aerodynamic center of pressure forward and reducing static stability. Remarkably, even modest elastic deformations can render an otherwise stable vehicle unstable, stressing the necessity of accounting for static aeroelastic stability from the earliest design stages.

Conventional design methodologies follow a hierarchical sequence in which the aerodynamic shape is determined first, followed by structural design, which is directed primarily by stress considerations. Aeroelastic effects, however, are often overlooked until later phases, when structural parameters are fixed and design revisions become costly.

This study presents a novel preliminary design methodology that integrates aeroelastic stability analysis at the earliest stage, when only the vehicle geometry is available, and no detailed structural design exists. The proposed framework represents deformations as a combination of generalized beam mode shapes, adapted to capture discontinuities in material and geometry, along with rigid-body contributions. Aerodynamic loading is modeled using a potential-flow panel method, enabling computation of the elastically deformed shape and its effect on static stability. Pareto-front analysis connects structural design parameters to overall weight and stability margin, providing designers with valuable trade-off insight. A Genetic Algorithm–based optimization then identifies structural configurations that achieve minimum weight while meeting prescribed stability requirements.