Technology Process of Carbon Fiber Prepreg Placement Molding and Product Performance Control
Author:Zhang Hong Ji
As an advanced engineering materials,composite material has many advantages,such as high specific strength,high specific stiffness,fatigue resistance,corrosion resistance and performance can be designed and many other advantages.It is widely used in the main structure and main bearing structure in aerospace,marine vessels,vehicles,wind power,energy and chemical industry and so on.As the prepreg tape laying material modification and structure molding of prepreg composite materials are carried out at the same time.Therefore,the performance of the laying products is very sensitive to the molding process,and the molding process affects the quality of the prepreg tape laying products.Due to the complexity of the laying process itself,the unreasonable part of the process will produce defects and size deviations,thus affecting its performance,service life and service performace.Because of the prepreg tape laying molding technology can greatly improve production efficiency,and can be accurately through the molding process control can greatly improve the quality of the laying products,it is the key technologies low-cost manufacturing of composite materials which has been developing fastest and most effcctively growing in recent year.So far,a lot of research has been done on the technology of prepreg tape laying and the properties of the products at home and abroad,but there are still some problems.The main manifestation is(1)during the prepreg placement,the mechanism of control and matching of the process parameters effect on the properties of the products are not clear.(2)The relationship between the formation,distribution,types and molding parameters of the prepreg tape laying product defects and the mechanism of the defects affecting the properties of the products are not clear.To explore the above problems,the performance of prepreg tape laying products is depends on the structure,components and laying process of prepreg tape.The influence of process parameters(tension,velocity,pressure and temperature)on the properties of prepreg tape placement products(physical properties,mechanical properties)and the defect of prepreg tape placement products are main research content.The method of theoretical research,simulation analysis and process experiment have been used.The following aspects are studied in detail.(1)Study on process technology of prepreg tape laying.Prepreg tape laying is a complex process in which the prepreg tape changes in physical state(geometry,deformation,etc.)and chemical states(molecular structure,crosslinking,etc.).The process parameters model and thermo-mechanical coupling model of prepreg tape laying were established to study the deformation rules and layability of prepreg tape under the parameters of laying process.The mechanism of the physical and chemical transformation of the prepreg tapes during laying was investigated,to lays the foundation for performance based process control methods.(2)Study on performance analysis and microstructure characterization of prepreg tape laying products.Firstly,by theoretical research on the elastic properties,strength properties,thermal expansion properties and thermal conductivity of the prepreg tape laying products,the theoretical prediction model of prepreg tape laying product is eatablished.Secondly,the prepreg tape laying product is observe and analyze by SEM,the microscopic defects of the use of field emission electron microscopy(FE-SEM)on the prepreg tape laying products were observed and analyzed,we can see the microscopic defects of the products are mainly included voids,matrix cracks,interfacial debonding.Further analysis shows that the the matrix crack and interface debonding are caused by the mismatch of the thermal expansion coefficient between the fiber and the resin matrix,and the voids are generated by the prepreg tape laying process.Further research process parameters,prepreg tape material and other factors with products defects and the formation of the correlation,reveal the formation of defects,influencing factors and regulatory principles.Reduce or avoid defects in the manufacturing process to provide theoretical guidance.(3)Study on the influence of molding process parameters on product performance.Through the combination of numerical simulation and experiment,the mesoscopic model of representative volume element(RVE)is established by finite element software ABAQUS,MSC.Patran/Nastran,by applying reasonable load and boundary conditions,the mechanical properties and physical properties of prepreg tape under the influence of process parameters are studies.When studying the effect of product defects on performance,element deletion method was utilized to implement all types of manufacturing defects.The FECM method is used to predict the elastic properties and thermal expansion properties of non-manufacturing defects,including the single manufacturing defects and the various kinds of defects.The thermos-mechanical coupling model of prepreg tape laying is established,the residual stress of the product under different temperature and pressure parameters was studied by means of finite element simulation.And the results were analyzed and compared to get the impact of various factors on residual stresses.(4)Study on the control method of molding process parameters based on performance.Firstly,a fuzzy PID controller based on Robust Extended Kalman Filter(REKF)is proposed.Based on the experimental platform of laying tension control system,the simulation results of the designed algorithm are verified by experiments.Compared with traditional fuzzy PID,the fuzzy PID controller based on REKF has strong anti-interference performance and robustness,and the winding tension control precision has been increased by 40%~42%.Secondly,a particle swarm optimization fuzzy PID control method of laying pressure is proposed.To increase the stability and adaptive ability of the pressure control system,A PSO fuzzy PID controller to adaptive optimization fuzzy parameters is constructed using particle swarm optimization algorithm,as a control strategy for laying pressure system.Finally,the mathematical model of temperature field of prepreg tape placement was established.The distribution of temperature field in laying process is analyzed.ABQUS software was used to model and simulate the whole laying precess,and the influence of the laying temperature on the velocity,rifidity and laying effect was studied.