Structural Analysis And Optimum Design Of Composite Laminates

With its outstanding mechanical properties,composite materials have been widely used in aerospace,naval architecture and ocean engineering,and other fields.Nevertheless,the unique directivity and layering of composite materials will also make their structural characteristics very different from those of traditional metal structures.Therefore,it is of great significance to analyze and optimize the structure of composite materials.In this paper,the most basic composite structure-laminated plate is studied.The finite element derivation of the laminates is carried out based on the first-order shear deformation theory,and the finite element program of the quadrilateral four-node laminate unit and the spring unit is prepared based on the Fortran language.The static and vibration problems of the laminate are calculated using a program.In the static analysis,the node displacement of the laminate and the stress of each layer are solved.Compared with the Ansys results,the error is within 5%.In the vibration analysis,the free vibration analysis of the laminate without elastic support and elastic support is first carried out.Compared with the Ansys results,the error is within 2%.It is proved that adding spring can improve the natural frequency of laminate,and the lower the natural frequency is,the higher the natural frequency is.Then the effects of various laying methods,number of layers and boundary conditions on the fundamental frequency of the laminate are discussed.Then,based on the Newmark method,the forced vibration of the laminate is studied.The response curve is almost coincident with the Ansys result.The effects of single-point and multi-point excitation,different excitation frequencies and damping coefficients on the forced vibration response of the structure are discussed.Finally,the Ansys software is used to analyze the harmonic response of the laminate from the frequency domain.In view of the designability of composite materials,the laminate is optimized.The Ansys software is used to optimize the laminated plates and the hat-stiffened plates respectively with the dimension parameters as the design variables,the Cai Wu criterion strength coefficient and the maximum deformation as the constraints and the minimum mass as the objective.Finally,based on genetic algorithm combined with Matlab and Ansys,the laminate is optimized with the layering order as the design variable,the Caiwu strength criterion coefficient as the constraint condition and the minimum deformation as the goal.