Analysis of wing morphing via frame buckling

This paper presents structural analysis methods to model morphing, achieved via buckling of struts in multi-element structural components. An exact element theory and an energy-based variational approach are used to deduce a closed-form relationship between actuator force and displacement, by firstly assuming an ideal actuator. Subsequently, the flexibility of the actuator is incorporated via a lumped parameter model to account for actuator-structure interaction. The single element actuation concept is extended to multielement frame architecture to produce displacements of an example aircraft tail section, by actuating one or two elements of the assembly. Hybrid actuation, combining large force with large displacement actuators is also introduced, whereby large shape changes can be achieved with optimum demand on the actuators. It is concluded that exact element theory has significant potential in deducing closed-form relationship between the actuator forces and structural displacements. The energy approach, based on the trial function to represent the displacements, is shown to be approximate, but sufficient. These closed-form relationships can be readily used in optimisation routines to achieve an optimal structure to produce structural shape changes.