Flight Dynamic Studies Of A Flexible Folding Wing Aircraft

Folding wing aircraft is an important potential design configuration for future smart morphingaircraft. The aeroelastic and flight dynamic problems during the folding process have gainedresearchers’ significant attentions. In this thesis, the entire folding process is simulated on ADAMSplatform with virtual prototyping technique. A theoretical aerodynamic model and an unsteady CFDaerodynamic model are used to investigate the dynamic behavior, respectively. The longitudinal flightdynamic characteristics of a folding wing aircraft considering aeroelastic effects are studied and theresults could provide references for the design purpose.The sub-structure models of the folding wing aircraft are constructed by finite element techniqueand the hinge constraints between each component are defined. Then according to modal synthesistheory, the finite element model of the aircraft is constructed by assembling each sub-structure model.Then the modal analysis and flutter analysis are both performed and the influences of folding angle onnatural characteristics and flutter characteristics are investigated, respectively.The simulation model is established on ADAMS platform: the modal information of eachsub-structure are imported into ADAMS; unsteady aerodynamic forces are calculated via subsonicdoublet-lattice method and applied to the structure through a external program; and a PID control lawis designed for longitudinal flight control. The flight of a folding wing aircraft is simulated and thelongitudinal responses through the entire folding process are characterized. The influences of elasticdeformation and folding angular velocities on the aircraft motion parameters are investigated andinterpreted.Based on the dynamic overset structure grids and the Euler equations, a coupled CFD/CSDmethod, which can be applied to multi-body system, is developed on ADAMS platform. Firstly,aerodynamic characteristics and dynamic response during the folding process are analyzed. Then theinfluences of the folding process on the longitudinal motion of the aircraft are investigated. Theresults are compared with those using theoretical aerodynamic model, and some meaningfulconclusions are obtained.