Composite Laminated Plates Vibration And Stability Analysis And Optimization Design

Composite materials have been widely used in aerospace, vehicle and navigation industry for its distinct advantages of high strength ratio, high stiffness ratio and tailorability. The development of modern aerospace industry demands more advanced aircrafts with stronger impetus and higher load-bearing capacity. As the main load-bearing components of aircraft, composite laminates are inherited with strong anisotropy. The change of fiber orientation angles and stacking sequences has a remarkable impact on structural performance; therefore it is of important practical significance to analyze the influence of the structure parameters on the vibration characteristics and structural stability. Researches on the vibration analysis, stability analysis and structural optimization design of composite laminates are presented in this paper.Firstly, the natural frequencies of free vibration of composite laminates are analyzed. Finite element method is applied to obtain the natural frequency of laminates. Calculation results are verified through the numerical analysis; the influence of layer numbers, fiber orientation angles, paving pattern and boundary conditions on natural frequency are analyzed. Numerical simulation shows that: the calculation method presented in this paper is accurate enough to solve the natural frequency of composite laminates under different boundary conditions; fiber orientation angles, paving pattern and boundary conditions have different levels of impact on the natural frequency.Secondly, the stability of composite laminates is analyzed. Classical laminated plate theory and stability theory are combined to deduce the calculation method of the critical buckling load of composite laminates under compression and shear loading. Numerical analyses are used to verify the accuracy of calculation theory. The influences of length width ratio, elastic modulus ratio, span thickness ratio, fiber orientation angles and boundary conditions on the critical compressive load are analyzed. Numerical simulation shows that: the calculation method presented in this paper is accurate enough to solve the critical buckling load of composite laminates; the length width ratio, elastic modulus ratio, span thickness ratio, fiber orientation angles and boundary conditions have different levels of impact on the critical buckling load.Finally, a double objective optimization model to optimize the natural frequency and stability of composite laminates is created. The fundamental frequency and critical compressive load are chosen as objective functions. An improved genetic algorithm is adopted to obtain the optimal fiber orientation angles of composite laminates with different length width ratios and different boundary conditions. Numerical simulation shows that: optimal results can effectively improve the fundamental frequency and stability of composite laminates; the optimal results are influenced by length width ratio and boundary conditions.