Strain-based geometrically nonlinear beam formulation for modeling very flexible aircraft

This paper introduces a strain-based geometrically nonlinear beam formulation for structural and aeroelastic modeling and analysis of slender wings of very flexible aircraft. With beam extensional strain, twist, and bending curvatures defined as the independent degrees of freedom, the equations of motion are derived through energy methods. Some special treatments are applied to the formulation to effectively model split-beam systems and beam configurations with multiple nodal displacement constraints. Using the strain-based formulation, solutions of different beam configurations under static loads and forced dynamic excitations are compared against ones from other geometrically nonlinear beam formulations.