Study On Modified Preparation Method And Machinability Of Aramid Fiber-reinforced Polymer

The excellent specific strength,specific modulus and impact resistance of aramid fiber give the fiber composite excellent physical and chemical properties,making it widely used in aerospace,military fixture,rubber,construction and other fields.However,the heterogeneous and anisotropic characteristics of the composite materials and the excellent material characteristics of aramid fiber also make the cutting performance of the AFRP poor.Mechanical processing is an indispensable process link after its formation,the research on the machining technology of AFRP has become a hot spot in recent years The lack of machining technology of aAFRP has become a bottleneck restricting its further development and applicationIn this paper,the resin-based aramid fiber composite material is taken as the research object,starting from the cutting mechanism,the cutting force model and the cutting defect generation model are established.Through the model analysis,the defect suppression strategy was proposed,the modification method of aramid fiber modified by ultraviolet-ultrasonic vibration was proposed,and the calculation method of the safe thickness of the resin on the composite surface was proposed.On this basis,modified AFRP were prepared,and the mechanical properties and cutting experiments of the composite materials were tested.The main research contents and achievements of the paper are as follows:(1)By analyzing the machining mechanism,a cutting force prediction model with the change of fiber direction angle is established.Based on the cutting force prediction,the mechanism of producing burrs defects in FRP was analyzed,and a defect generation model was established.The critical conditions of fiber shear fracture and bending fracture are proposed,and the relationship between the safe thickness of the surface layer resin and the cutting force is proposed,which provides parameter guidance for the preparation of composite materials(2)Ultrasonic vibration modification of aramid fiber surface was carried out under ultraviolet(UV)environment,and the surface morphology,tensile strength and functional group content of the modified aramid fiber surface were characterized.Based on the characterization results,the best modification process parameters were determined,and it was verified that the ultraviolet irradiation environment can accelerate the ultrasonic vibration modification process(3)The milling force prediction model is verified through the fiber composite milling experiment.The mechanism of the influence of tool nose radius,cutting depth and modification method on cutting force is analyzed.The mechanism of cutting surface roughness and surface morphology was analyzed.For the modified AFRP,the milling burr defects were obviously suppressed,which verified the availability of the surface resin safety thickness model.