Path Planning Method Of Fiber Placement In Variable Stiffness Design Of Laminated Plates

Variable stiffness composite laminates are of great significance for the development of high specific strength,specific stiffness and other characteristics of composite materials.The emergence of automated fiber placement technology also makes it possible to manufacture variable stiffness laminates,and the development of multi-level optimization framework also simplifies the complexity of variable stiffness laminate design.At present,there are many problems in the design and manufacture of composite laminates,such as the representation of distributive design variables,the nonconvex optimization and the fiber gap/overlapping in manufacturing.Based on the current techniques of laminated plate design and manufacturing,this paper proposes a NURBS representation method for ply angle distribution,and a reverse method for angle retrieval,considering the curvature constraint and parallelism constraint of ply angle to ensure the manufacturability.Finally,a path construction method based on the reverse calculation of the stream function for the trajectories is proposed to construct a continuous fiber path.The main work of this paper includes the aspects as follows:(1)The current optimization design process of variable stiffness laminates is studied,including the design parameterization method based on fiber angle and lamination parameters,the mechanical property computation based on isogeometric analysis,and the multi-step optimization framework.(2)The lamination parameter expression of stiffness in the constitutive equation of laminated plate is studied,including the method of calculating the lamination parameter from the fiber angles of layers,and the feasible domain of lamination parameters.Furthermore,the optimal design model of laminated plate based on lamination parameter is discussed,by which the optimal lamination parameter distribution can be solved.(3)A representation method of the angle distribution for fiber placement based on the NURBS basis functions and the corresponding reverse model are proposed.(4)A fiber path construction method based on the least square approach is proposed,which can extract the corresponding NURBS contours as fiber paths for fiber placement in the manufacturing of laminated plates from the angle distributions of different plies.(5)The whole process of lamination parameter optimization,fiber angle retrieval and fiber path construction of rectangular laminated plates is studied.The experimental data show that the optimization design method described in this paper is effective.