Forward-swept Wing Aircraft Composite Aeroelastic Tailoring Design Analysis Technique

Torsional divergence problem is an obstacle in the application of forward-swept wing aircraft, despite its many advantages in aerodynamic characteristics, such as high critical Mach number, low wave drag and no wingtip stalling. Isotropic metals are the most widely used materials in aircraft structure, which unavoidably leads to heavier structure weights in designing forward-swept wing aircraft. Fortunately, aircraft designers can improve the divergence speed of forward-swept wings aircraft by means of aeroelastic tailoring technique.Aeroelastic tailoring technique involves mechanics of composite materials, aeroelastic dynamics and optimization methods. In this thesis, the history and relative theories of aeroelastic problem are reviewed. The mechanism of torsional divergence and how aeroelastic tailoring technique solving torsional divergence is also illuminated. Meanwhile, the aeroelastic tailoring technology is applied to a forward-swept wing aircraft research project in this thesis.The anisotropic mechanical characteristics of composite materials are critical path to implement aeroelastic tailoring. The design parameters of composite laminated structure consist of ply thickness, stack sequence and orientation, modifying these design variables can control the aeroelastic characteristics of aircraft wings which is because of different properties of strength and stiffness of composite laminated structures, that is the coupling of bending and twisted stiffness. Some numerical analyses are provided in the thesis to demonstrate the contributions of aeroelastic tailoring to forward-swept wing aircrafts.The optimization of composite materials structure is usually difficult, because of too many design variables, complex constraints and highly nonlinear behaviors. One of effective method is parameterized design by properly selecting design values. ANSYS provides with a practical method to solve multi-parameters design problem based on finite element analysis technique. An efficient structure optimization program is designed using the APDL (Ansys Parameter Design Language) for the optimization of composite materials aircraft structures. Finally aeroelastic tailoring technique of composite laminate is applied to a forward-swept wing structure to improve divergence speed.