The tools necessary for the aeroelastic design of very flexible aircraft with geometric nonlinearities are limited. The present work describes a novel model that integrates a modal formulation with a three-dimensional geometrically nonlinear structural dynamic model, for the effective study of very flexible aircraft structures under impulsive loads, such as gusts, that cause large displacements.
The presented modal formulation links linear segments with nonlinear coupling terms. The model nonlinearity is captured by dividing the wing structure into several spanwise segments, each having large rigid-body displacements but may assume to have linear elastic deformations. The required number of modes may be reduced by using fictitious masses at the segment interfaces. The structural dynamic model based on co-rotational linear frameworks is developed, matching the modal formulation characteristics.
