Research On Carbon Fiber Cloth Reinforced Composite Spring

Spring is a kind of mechanical parts with buffering,vibration damping and energy storage function.It is widely used in many fields,such as automobile,aerospace and railway vehicles.In recent years,the automobile industry has focused on energy saving and emission reduction,so it is urgent for the automobile to develop in the direction of lightweight.Therefore,a large number of researches have been carried out on carbon fiber reinforced polymer(CFRP)spring domestic and overseas.In view of the problem that the mechanical properties of the existing CFRP springs are far less than the mechanical properties of the same size metal springs,the study of carbon fiber cloth reinforced CFRP spring is carried out in this paper.In this paper,T-700 SC carbon fiber was used as reinforcement,and AG-80/328composite resin was used as matrix.CFRP spring were prepared by low pressure contact,pullout,molding and resin transfer molding.The CFRP spring were strengthened with carbon fiber cloth wrapping process.The effects of wrapping angle and layer number of carbon fiber cloth on tensile strength,bending strength of CFRP mandrel and CFRP spring stiffness were studied.The use of microcomputer controlled electro-hydraulic servo universal testing machine for mechanical properties testing of the mandrel and the spring,scanning electron microscope was used to observe the micromorphology of the cracks at each specimen,the strengthening mechanism of carbon fiber cloth wrapping process was analyzed,and the carbon fiber cloth wrapping process was verified by theoretical calculation.The influence of the wrapping process of carbon fiber cloth on the physical properties of CFRP mandrel is studied.The different carbon fiber wrapping angles of 30°,45°,60°and 90°are studied and the number of different layers of carbon fiber cloth is 1layer and2layers,respectively.The influence on the size of CFRP mandrel,fiber mass fraction and volume fraction.The results show that the carbon fiber wrapping process has little effect on the above physical parameters.The influence of carbon fiber cloth wrapping process on tensile properties of CFRP mandrel was studied.The results show that the strengthening process of carbon fiber cloth wrapping is not obvious to the tensile strength of the mandrel.The 2-layers 90°carbon fiber cloth wrapping process can improve the tensile strength of the CFRP mandrel from751.2MPa to 831.2MPa,and the lifting range is only 10%.The reason is that carbon fiber itself is a material with very high longitudinal modulus of elasticity,carbon fiber wrapping strengthening process cannot improve the longitudinal properties of carbon fiber.The effect of carbon fiber cloth wrapping process on the bending properties of CFRP test mandrel was studied.The results show that the carbon fiber cloth strengthening process has a significant effect on improving the bending performance of the mandrel,and with the increase of the wrapping angle,the enhancement effect is better with the increase of the number of layers.The most obvious strengthening effect of 2-layers cloth 90°wrapping process can improve the bending properties of the CFRP mandrel from 692.7MPa to1220.6MPa,and the lifting range is 76.2%.The reason is that the carbon fiber cloth wrapping process can effectively improve the transverse elastic modulus of CFRP materials.Enhance the shear strength of CFRP and give full play to the advantage of high longitudinal elastic modulus of carbon fiber.The strengthening effect of the large angle wrapping process and the multilayer cloth wrapping process is more ideal.Therefore,the CFRP spring was strengthened by the2-layer cloth,45°,60°and 90°wrapping process.The results show that the strengthening process of carbon fiber cloth can effectively improve the stiffness of the spring,and the strengthening effect increases with the increase of the wrapping angle.Among them,90°carbon fiber cloth wrapping process is the best.The stiffness of the CFRP spring is raised from 4.45×10~3 N/m to 12.69×10~3 N/m,and the lifting amplitude is 185.1%.Through the theoretical model calculation,it is found that the actual experimental results are on the low side,such as reducing the deviation of the angle of CF cloth during pullout and reducing the entry of air moisture and other impurities.