Study On Mechanical Behavior And Fiber Angle Optimization Of Variable Stiffness Laminates

With the increasing application of composite materials in automotive industry production,especially on body panels,research on how to improve the structural properties of composite materials is becoming more and more in-depth,and research directions are becoming more and more comprehensive.In recent years,automatic wire laying technology has become one of the mainstream technologies for the preparation of fiber composite materials,and the functions of automatic wire laying equipment have become more and more perfect.The research on composite materials is no longer satisfied with the composite laminated structure under the traditional linear fiber layering method.In-depth study and discussion on the effects of fiber strands on the mechanical properties of composite laminates.The mechanical properties of the fiber composite laminate structure are closely related to the matrix properties and fiber angle.The change of the fiber angle will affect the rigidity of the composite laminate.Therefore,the laminate prepared by the variable angle fiber layering method is called composite material.Variable stiffness laminates.In this paper,the research on the rule of laminating fiber,mechanical properties and fiber angle optimization of variable stiffness laminates is carried out.In this paper,the definition of variable stiffness laminates is described in detail.The current research status of mechanical properties and fiber angle optimization of variable stiffness laminates is analyzed.Some problems existing in the current research species are analyzed,and the main research of this paper is clarified.content.The main research contents of this paper mainly include studying the variation law of fiber angle,determining the linear function as the reference path of variable angle fiber,expounding the content of translation method and parallel method,and comparing the advantages and disadvantages of the two layering methods.The translation method was chosen as the layering method for variable stiffness laminates.Then the numerical simulation method is used to study the mechanical properties of the variable stiffness laminate.Based on the lack of finite element modeling software for variable stiffness laminates,this paper uses the tcl/tk language to transform the finite element of the variable stiffness laminate based on the Hyper Mesh/Opti Struct platform.The modeling tool "VS Laminate Define Tool" and the optimization tool "VS Laminate Optimization Tool" were redeveloped.After the development,the accuracy and reliability of the two tools were verified by examples.The finite element modeling tool “VS Laminate Define Tool” of variable stiffness laminate was used to model and solve the variable stiffness laminate under plane static force.The deformation and stress distribution in the simulation results were analyzed.The influence of two factors,fiber angle and rotation angle,on the deformation and stress distribution regions,and the denser the fiber curve,the smaller the stress.Then the buckling performance of the variable stiffness laminate and the linear fiber laminate is compared.The first-order buckling load of the variable stiffness laminate is significantly larger than that of the linear fiber laminate,and the variable stiffness laminate with the rotation angle of 90° at the same fiber angle is obtained.The first-order buckling load is greater than the variable-stiffness laminate with a rotation angle of 0°,and the variable-stiffness laminate has more excellent performance against elastic deformation.The maximum failure index of linear fiber laminates and variable stiffness laminates under compressive load is compared.[0±<15|60>]2s and [90±<15|60>]2s two kinds of variable stiffness laminates The failure load is 12.68% higher than the [0/90/±45]s linear fiber laminate.Finally,using the variable stiffness laminate optimization tool “VS Laminate Define Tool”,the variable stiffness laminates with the number of layers 1,2 and 4 were optimized respectively,and the three different layups under tensile load were obtained.The optimum fiber placement initial angle and end angle of the variable stiffness laminate,ie two control parameters of the fiber angle function.