Rotational Extrusion 3D Printing Process Of Carbon Fiber Reinforced Epoxy Resin

Carbon fiber reinforced composite materials are very good lightweight materials and have been widely used in aerospace,automotive,civil engineering and other fields.The mechanical properties of short carbon fiber reinforced composites are closely related to fiber orientation.However,traditional extrusion,injection and other processes are difficult to achieve fiber orientation control.The 3D printing process based on the principle of discrete/stacking uses dots,lines,and surfaces as the basic units to form parts layer by layer,which provides a new and effective way to control fiber orientation.The research goal of this paper is to use fiber-reinforced composite material rotating extrusion 3D printing to achieve controllable fiber orientation printing,and to obtain the law of influence of process parameters on fiber orientation and part performance.Around this goal,this article conducts research in the following four aspects.First of all,aiming at the problem of fiber orientation control,carbon fiber reinforced epoxy resin composite materials were used to build a set of rotating extrusion 3D printing experimental platform.The platform is mainly divided into three parts: space movement,storage and feeding,and terminal extrusion.A terminal extrusion device that can realize rotary extrusion is designed and manufactured.The matrix material system is designed and prepared,so that the matrix material can meet the process requirements of extrusion 3D printing.Four lengths of 220?m,111?m,69?m and 26?m are selected from commonly used carbon fibers as reinforcing fibers.The mass ratio of epoxy resin,curing agent,thickener,and carbon fiber in the composite material is100:15:10:10.Then,numerical simulation is used to analyze the rotating extrusion flow field inside the extrusion mechanism.Analyze the simulation results: Comparing the results of the overall flow field,the flow lines show obvious swirling flow.The cross-sectional velocity distribution near the exit area is high around the circumference and low in the center;with the increase in speed,the fluid velocity in the contact layer close to the rotating wall increases,and at the same time,the attenuation velocity of fluid velocity inward transmission also increases,200r/min The effect of the rotating wall on the internal flow field reaches the maximum under the condition of speed.Then,the orientation of the short fiber in the printing track is controlled by changing the nozzle rotation speed: as the rotation speed increases,the average outside angle of the composite material first increases and then decreases,and the average tangential angle first decreases and then increases,the maximum value condition It varies with the length.Generally speaking,the fiber orientation reaches the maximum value when the rotation speed is 200r/min or 300r/min.After the rotation speed reaches 400r/min,the fiber orientation is weakened.Finally,the influence of different fiber orientation states on the performance of printed products is analyzed.As the speed changes,the bending performance,tensile performance and Vickers hardness all show a trend of first increasing and then decreasing,and the optimal performance appears at the speed of 200r/min or 300r/min.The shorter the fiber,the worse the reinforcement effect of the spinning process.Realize the control of fiber orientation through the spinning extrusion 3D printing process,revealing the law of orientation control and performance changes.This technology is applicable to other fiber thermoset composite material systems,and the research results have an important reference for composite material systems with similar rheological properties.