Study On The Optimization Of The Laying Of Curved Fiber In Composite Laminated Structure With Variable Stiffness

Because of its excellent mechanical properties and designability,the variable-stiffness laminated are widely used in aerospace applications.The use of fiber angle-varying traction sewing technology(VAT,Variable Angle Tow Placement)to replace the traditional straight fiber monolayer can bring more design space,and can effectively solve the stress concentration problem in the traditional delamination zone or opening,which can bring more design space and can effectively solve the stress concentration problem at the traditional delamination area or opening.But curved fiber laying brings greater design freedom,but also increases the structural design parameters of composite materials,and the relationship between design variables and structural mechanical response becomes more complicated.In order to make better use of curved fiber laminated structure in engineering practice,it is urgent to study the design method of curved fiber laying track.This paper mainly aims at the optimal design of curved fiber track of perforated plate and stiffened plate.(1)The statics model of open-hole plate based on principal stress method is optimized and the design platform is constructed.By comparing the results of static analysis before and after optimization,the effectiveness of curved fiber laying to solve the stress concentration phenomenon is verified,and its influence mechanism is deeply explored.To improve the computational efficiency,the PATRAN is developed twice based on MSC.PCL language,and the design platform is constructed to realize the automatic iterative generation of principal stress trajectory,and the practicability of the design platform is verified by two engineering examples.(2)The validity of the buckling optimization problem of curved fiber laminated structures based on piecewise function method and its influence on parameters are studied.Buckling instability is one of the important failure forms of compressive thin-walled structures.in order to deeply study the effect of function trajectory parameters and geometric parameters on the buckling performance of the structure.In this paper,the optimal buckling model of curved fiber laminates and stiffened panels is constructed on the idea of discretization of continuity function.The influence rule of the parameters is obtained and the effectiveness of the fiber laying on the buckling performance is verified(3)Genetic algorithm is used to optimize the buckling model of curved fiber reinforced plate based on function method.The buckling of curved fiber reinforced plate is a typical nonlinear multipole problem.It is difficult to analyze the influence rule by parameter sensitivity.In this paper,genetic algorithm is used to optimize the buckling performance of curved fiber reinforced plate,and the maximum buckling load of curved fiber under different spacing is obtained.The effect of bar spacing on the maximum buckling load of curved fiber reinforced plate was studied.