Study On Static Load Performance Of Composite Laminates With Curvilinear Fibers

Due to the advantages of high specific strength and high specific stiffness,composite materials have been widely used in aerospace,automotive and other fields.The development of automated fiber placement technology allows fibers to be laid out in a single layer in a predetermined trajectory,no longer limited to the traditional linear form of ±45°,0°,and 90°.The development has greatly expanded the space of the laminate design,which provides a convenient condition for the performance of the material to a greater extent.Buckling is one of the important failure modes of composite thin-walled stiffened structures.Introducing variable angle laying into stiffened structures can improve the ultimate load of the structure.In this paper,the buckling behavior of composite laminates and stiffened structures with variable angles are studied,and the tensile failure of composite laminates with variable angles is studied.Based on this,the buckling analysis program of variable angle composite laminates and the graphical user interface program of stiffened composite structures are developed.Firstly,the finite element formula of buckling analysis of the variable angle composite material is presented,and the governing equations of linear buckling and nonlinear buckling are obtained.Based on this,the finite element static analysis and linear buckling analysis program for the variable angle composite is developed.Compared with the examples in other papers,the accuracy of the calculation results is less than 5%.Secondly,the above analysis method is extended to more comprehensive commercial software.Through the secondary development,the crushing analysis model of the variable angle stiffened composite laminates based on the finite element method is established,and then carrying capacity and failure analysis of stiffened composite plate is conducted.The stiffened plates under different working conditions,different stiffened forms,and different layup designs are analyzed.The variable angle placement that is superior to conventional layups is presented.The effects of initial geometric imperfections,viscosity coefficient,rib design,rib off-plane displacement constraints on buckling mode and ultimate bearing capacity are analyzed.Under the condition of the shear load,under the polynomial trajectory,the better range of T0 and T1 of the hat-shaped stiffened plate is determined.Thirdly,compared with the compression analysis,the tensile analysis of the composite structure is relatively simple,but it is also an important index for the static load analysis of composite materials.The tensile behavior of variable angle composite laminates is also studied.The tensile strength of the variable angle composite laminates was measured and the failure behavior was simulated.Using the idea of variable angle,the direction of the maximum principal stress of is discretized into the finite element calculation model of the notched plate,and the failure strength is superior to the traditional layup,which proves the superiority of the variable angle laying.Finally,based on the crushing analysis model of the stiffened composites structure,based on the commercial software ABAQUS,the stiffened composite structure crushing analysis program was developed.It is more convenient for later research.