Study On Interlayer Performance Regulation Of AF Reinforced Thermoplastic Composite Additive Manufacturing

Based on the CFRT additive manufacturing technology,the research on the interlaminar performance regulation mechanism of aramid fiber reinforced thermoplastic composite additive manufacturing was carried out,which provides a low-carbon,green,and short-process rapid forming method for aramid fiber reinforced composites.Due to the weak link of interlayer bonding in CFRT additive manufacturing,the preparation and performance research of aramid fiber reinforced thermoplastic composite micro-wire,the pore mechanism research of AF / PLA additive manufacturing composite component,the interlayer performance regulation research,and the CFRT additive manufacturing forming device and typical parts forming research were mainly carried out.The surface sizing agent of aramid fiber generates bubbles inside the AF / PLA composite micro-wire prepared by melt impregnation,so that the resin wrapped fibers were uneven and there was resin agglomeration.A three-stage fiber pretreatment melt impregnation preparation method and process with constant temperature water bath desizing,multi-stage heating fiber spreading,resin powder adsorption and impregnation were proposed.The on-line and efficient integration of aramid fiber pretreatment and melt impregnation can improve the impregnation effect of composite micro-wire from one time to two times,and reduce the porosity.The properties of composite micro-wire were determined by combining SEM,CT technology and mechanical property test.Aiming at the forming of AF / PLA composites,the pore calculation model of CFRT additive manufacturing based on the pore and fiber orientation parameters of composite micro-wire was established.The CT test technology was used to observe and calculate the pores of composite components with different fiber orientation structures.The CT test results were compared with the calculation results of the model,and the validity of the pore model was verified.The porosity of full filling forming with different composite micro-wire sizes were predicted.It was concluded that the smaller the porosity of composite component was formed by the larger the diameter of the composite micro-wire,under the same layer thickness.The porosity of composite components was controlled by adjusting the layer thickness and printing spacing.The relationship between porosity and interlayer performance of composite materials was explored,and the multiple regression equation between process parameters and interlayer performance and porosity was obtained to predict the performance of composite materials.The interlayer bonding area of composites with different fiber orientations was established,and the relationship between the interlayer properties of composites with different fiber orientations and the interlayer bonding area was explored.In order to improve the interlayer properties of aramid fiber reinforced thermoplastic composites,a method of interlayer reinforcement based on surface printing and Z-direction planting yarn was proposed.The Z-direction surface was formed by additive manufacturing to increase the interlayer contact area,and the continuous and curved Z-direction fibers were introduced to form the plane layer by layer.The multi-fiber orientation and Z-direction cross-layer structure of composite components were formed to further improve the interlayer mechanical properties of components.The fiber structure design,path planning,sample forming and other aspects were studied,and the mechanical properties between the layers of the formed composites were tested to verify the feasibility of this method.According to the proposed three-stage fiber pre-treatment process method,the functional upgrading of the composite filament preparation device was carried out.A series of aramid fiber reinforced thermoplastic resin composite filaments were prepared by integrating the pre-treatment device of constant temperature water bath desizing,multistage heating fiber spreading,resin powder adsorption and impregnation,and seamlessly connected with the melt impregnation device.It provides a composite filament with excellent impregnation effect,low porosity and high dimensional consistency for CFRT additive manufacturing.Based on the AF / PLA additive manufacturing composites,the nozzle structure optimization and wire feeding mechanism were studied to improve the effective bonding between the forming layers of the AF / PLA additive manufacturing composites.The above mechanism was integrated into the multi-axis CFRT additive manufacturing device.Based on the AF / PLA composite micro-wire,the path planning was combined with the Z-direction forming of pores and surfaces.The typical structures of the Z-direction non-perforated aramid fiber reinforced skeleton and the complex surface reinforced area were formed respectively,which explored a new material system for the additive manufacturing of CFRT reinforced composites.It also provides a rapid near net forming method for aramid fiber reinforced thermoplastic composites.