Control of Composite-Wing Oscillation Coupling

The control of coupled flexural–torsional oscillations of a composite wing by means of monoclinic structures in a reinforced plating is considered. Decomposition of the potential energy of deformation and kinetic energy of natural oscillation modes into coupled and uncoupled parts allows us to introduce two coefficients (as measures of the coupling of oscillation modes) that integrally consider the effect of the geometry and reinforcement structure on the dynamic-response parameters of the wing. These coefficients describe the elastic and inertial coupling of the natural oscillation modes, respectively. Numerical studies are performed to assess the effect of the orientation of considerably anisotropic carbon-fiber-reinforced plastic (CFRP) layers in the plating on natural frequencies, loss factors, and coefficients of elastic and inertial coupling for several lower tones of natural flexural–torsional oscillations of the wing. Combined analysis of the results obtained shows that, for each pair of flexural–torsional oscillation modes, there are orientation-angle ranges of the reinforcing layers where the inertial coupling caused by asymmetry of the cross-sectional profile with respect to the major axes of inertia decreases right down to complete extinction due to the generation of elastic coupling in the plating material. These ranges are characterized by two main features: (i) the difference in the natural frequencies of the pair of flexural–torsional oscillation modes is minimal and (ii) the natural frequencies of flexural–torsional oscillations belong to a segment restricted by corresponding partial natural frequencies of the pair of oscillation modes.