Static Analysis And The Double Objective Optimization Of First Natural Frequency And Sound Power On Laminated Plates

With the rapid development of modern aerospace industry, the requirements of high power, low noise and high load are put forward for the aircraft, which means that the sound vibration performance and carrying capacity of the structure face more severe challenges. Composite laminates have been widely used in the aerospace industry because of their excellent properties such as specific strength, specific stiffness and fatigue resistance, easy designed, and so on. In practical applications, the structure of laminated plates will be stimulated inevitably by the external excitation and have acoustic radiation, and the vibration of the laminated plate is easy to cause the deformation of the structure. So it is important to study the sound vibration characteristics and bearing capacity of composite laminates in the aerospace field. At present, most scholars only choose some special fiber laying angle to study the structural properties of laminates, which greatly limits the flexibility of the design. In this paper, the vibration, acoustic radiation performance and bearing capacity of the laminated plates is considered.Firstly, a layerwise theory with finite element method was used to calculate natural frequency of the free vibration of the composite laminated plates with different fiber orientation angle. The calculation results have been verified by numerical simulations. Based on the numerical simulations, the laying form of the fiber, width-depth ratio and elastic modulus ratio on the plate structural parameters, the first natural frequency of the laminated composite plates with different fiber orientation angle were then discussed.Secondly, the forced vibration of the damping laminated plates has been solved by numerical method. Based on the acoustic radiation mode, the effects of boundary conditions, the location of exciting force, the fiber orientation angles, the laying form of the fiber, elastic modulus ratio and width-depth ratio on the plate structural parameters, the sound power of the laminated composite plates are then discussed. The results show that the fiber laying angle and width-depth ratio have great influence on the acoustic radiation power of the laminated plates.According to the above analysis, the problems of the first natural frequency and the sound power of acoustic radiation as optimization objective function was considered. The double objective optimization design of maximum the first natural frequency and the minimum sound power on composite laminated plates’ fiber orientation angles have been carried out by the parallel selection genetic algorithm. The optimization results show that it can obtain the best laying layer of laminated plates with different boundary conditions, which effectively improve vibration and acoustic properties of the laminate structure.Finally, the static analysis of the optimal laying layer of laminated plates with four clamped edges have been studied by ANSYS software. The state of the laminated plates’ system is subjected to an external load. So it will provide some referenced data of stress and displacement for the engineering design personnel to design the composite laminated plate in practical application.