Study On Additive Manufacturing Of Fiber Reinforced Thermo-plastic Composites

Fiber reinforced thermoplastic composites(FRTPCs)are widely accepted in the fields of aviation and aerospace for excellent mechanical properties.Traditional manufacturing techniques of FRTPCs such as injection molding,compression molding and filament winding have several limitations such as high cost of molds,complicated processes,relatively long forming time and difficulties in fabricating complex components.Hence,additive manufacturing(AM)for FRTPCs based on computer aided design(CAD)was proposed by a few scholars.AM for short fiber reinforced thermoplastic composites(SFRTPCs)was firstly studied and achieved,but the improvement on mechanical properties was not obvious.Continuous fiber reinforced thermoplastic composites(CFRTPCs)have higher mechanical properties.However,few research literature mentioned AM for CFRTPCs,and scarcely any prototype has been made public.Up to now,no mature technology has been applied to practical engineering.Therefore,theoretical analysis,device developing and mechanical experiments were conducted in this paper to clarify the method,device and processing parameters of manufacturing CFRTPCs based on fused-deposition-modeling(FDM).The principal content of the research includes:Bonding mechanisms at the interface between continuous fiber and poly(lactic acid)(PLA)were analyzed,methods for fabricating CFRTPCs based on FDM was studied and devices to directly print composite parts were developed which consist of building platform,extrusion nozzles,control system and computer,laying a foundation of subsequent exploration on processing parameters of CFRTPCs.Mechanical experiments were conducted to investigate the influence of printing parameters on forming quality including shape accuracy and mechanical properties which play important roles in comprehensive performance of CFRTPCs.Shape accuracy control mainly deals with controlling the quality of surface profile by means of regulating the processing parameters such as printing speed,temperature,tension force of fiber.Properties control means to optimize the quality of mechanical properties by adjusting parameters including printing speed,temperature,distance between nozzle and building platform,thickness and printing path.The research on the modification of CFRTPCs by photosensitive resin was carried out,the influence factors of interfacial bonding strength between fiber andresin were investigated and the modified principle of photosensitive resin was illustrated.The device capable of manufacturing continuous fiber reinforced and photosensitive resin modified Polycaprolactone(PCL)composites was developed Further studies referring to modification effect of composite interface and mechanical properties were systematically conducted and analyzed.