Study On Effects Of AFP Compaction Roller On Quality In Fiber Placement Process And Optimal Design

Advanced composite materials(ACM)have become the basic materials of aerospace engineering,while the automated fiber placement(AFP)is a typical example and low-cost manufacturing technology for composite automated molding that developed and applied widely in developed countries such as Europe and US in the past 30 years,and improving greatly the utilization of composite prepregs and production efficiency.As the key component of the AFP equipment,the compaction roller contact directly with tows at its elastic layer to provide a certain compaction force and velocity.Different material properties and design parameters and structural forms have direct and significant impact on the quality in fiber placement process.In order to improve the pressure distribution consistency and contact time of each prepreg tow in AFP process,compaction roller must has large high pressure distribution uniformity and contact areas.Firstly,this paper has established the simulation model of AFP and set up the corresponding test platform,where has analyzed silastic compaction rollers of different stiffiness by simulations and experiments in fiber placement process,and presented the test method of pressure sensitive film on the pressure distribution and contact areas.The results show that silastic compaction rollers made with lower stiffiness exhibit larger deformation,and it is easier to adapt to unevenness of the contact surface and curvature tools,while the contact areas with tows are larger,but the pressure distribution down faster at both ends of the axis on the flat tool.Therefore,laying large curvature and plane tools should be preferred to compaction roller material of lower hardness and higher.Secondly,in order to research alone influence of the pressure distribution nonuniformity and contact areas on interlaminar shear strength(ILSS),this paper has prepared composite laminates and tested microstructure of pore distribution and fracture mode of samples and mechanical properties of ILSS.The results through the mechanical performance testing show that the pressure nonuniformity is decreased by 39.5%,and the ILSS is increased by 8.9%.The contact areas are increased by 44.4%,and the ILSS is increased by 5.0%.Increasing the pressure distribution uniformity and contact areas can effectively improve mechanical properties of laminates.Finally,in order to improve the pressure distribution uniformity as the main evaluation index this paper has optimized design parameters of the compaction roller,and presented the test method of orthogonal parameters with single factor simulation,and having got the compaction roller diameter is 80 mm and length is 120 mm.The verification results show that optimized compaction roller can reduce the pressure distribution nonuniformity by 15.9%at the maximum,which can effectively improve the fiber placement quality and ILSS.Aimed at the problem of uneven pressure distribution when the integral flexible pressure roller is laid on the large curvature mold,a multi-piece flexible pressure roller structure has been designed,and the pressure distribution nonuniformity of multi-piece flexible compaction roller is decreased by 76.6%compared to the integral flexible compaction roller through structural optimization.To ensure same maximum displacement of the compaction roller unit,the minimum radius of curvature for the concave and convex is 384.5 mm and 573.5 mm,while ensuring the same curvature,the minimum radius of curvature is 473.8 mm.