Optimal Design Techniques Study With The Elastic Tailoring Application Of The Aircraft Composite Structure

The integrated optimization for composite structures of aircraft is a kind of technique of making full use of composite design-ability and improving the synthetic performance of aircraft structures. With the utilization of the bending-twisting couple effect of laminated composites, the box-wing structure of aircraft can be designed more light, and meet all kinds of design requirement, such as stiffness, strength and aero-elasticity, etc.The thesis deduces the bending-twisting coupled constitutive equations of the rectangular laminated wing-box through the theory of laminated plate, sets up mathematical expression of the bending-twisting coupled coefficients, analyzes the bending-twisting coupled effect and curves with change of the laminated rotation and the lamina angle ply rotation. Based on these theoretical work, the thesis also designs the bending-twisting coupled optimization algorithm and flow chart, validates the algorithm through some numerical examples by using MATLAB program. From these work, several elastic tailoring strategies are proposed, which takes account of the damage tolerance requirement of laminated composite, and making for the aero-elastic design of composite structure.The thesis sets up the finite element model of a developing composite wing-box structure by using ANSYS software package. On the base of numerical computation, the geometric parameters of sections in the wing structure are all optimized. In the optimization process, the bending-twisting coupled conception of the composite wing-box structure is fully taken into account. For the structural design optimization, the thesis designs a hierarchical optimization technique to make a complicated structural optimization more effective and practical. Finally a set of preferable results for real engineering are obtained.The thesis research work attempts an effective integrated technical route for modern structural design optimization, that is, creating structural geometrical model through UG, then transmitting the model to ANSYS and processing structural analysis or optimization. In the process, the thesis summarizes many significant experiences.The studied bending-twisting coupled constitutive equations of wing-box and the elastic tailoring methods as well as the proposed hierarchical optimization technique in this thesis not only benefits to theoretic research but also practical applications.