| Spring is widely used in the industrial production and daily life as a basic component. But at present, the quality and properties of traditional metal spring have reached a bottleneck. Because of the high specific strength, low density, corrosion resistance and excellent fatigue performance, carbon fiber reinforced composite materials is the future trend of the high performance materials. In this paper, firstly, in order to determine the formula for the composite spring epoxy resin matrix, the effect of kinds and proportions for epoxy resin, curing agent, diluent on the mechanical properties of epoxy resin matrix were studied through the resin casting body mechanics performance test. Secondly, the effect of twisting process on the microstructure and properties of composite spring mandrel bar which is prepared by molding process was studied. Finally, it explores the carbon fiber reinforced composite spring preparation technology combined with the spring force by spring mandrel winding carbon fiber strengthen layer method of spring to strengthen, on carbon fiber strengthen braid angle and the braid layers on the performance of the composite spring effect.The experimental results show that the aromatic amine curing agent of epoxy resin can obtain higher tensile strength. By using composite epoxy resin can effectively use synergy between resin and excellent comprehensive properties of the epoxy resin matrix. E-44 epoxy resin has higher tensile strength and AG-80 epoxy resin has a good shear strength and add E-44 epoxy resin to AG-80 to maintain strong shear strength and improve the tensile strength. When mAG-80:mE-44=60:40 resin casting body has the most excellent mechanical properties, at this time, the tensile strength of resin casting body, compared to the pure epoxy resin E-44 and pure AG-80 epoxy resin respectively, improves by 11.69% and 34.38%. And diluent was added to increase the impact toughness of the resin matrix, while scanning electron microscopy analysis showed that the diluent added does not make epoxy resin matrix transform to ductile materials, but when the adding quantity is 15/100, impact toughness increased 43.69%. Comprehensive analysis identified following resin matrix formulations for thinner mAG-80:mE-44:m diluent:mcuring agent =60:40:15:25. At this time, shear strength reached the 127 MPa and impact strength of reached 46.7 KJm-2, tensile strength for 79 MPa.The appropriate twist can also can also improve density and reduce the porosity of carbon fiber composite material. However, if the twist is too large, the composite density will get reduced. When the twist is 20n/m, the maximum density is 71.4% and the porosity is 0.293%. At the same time, the carbon fiber reinforced composite bar with different twist were manufactured by compression molding. Within a certain range of twist, with the increase of twist, bar tensile strength increases gradually, but if it is more than the critical value of twist, the tensile strength decreased. Scanning electron microscope observation indicated that proper twist to resin and carbon fiber full infiltration, improve the interfacial properties of the resin and fiber, so as to improve the tensile properties of the composite bars. When the twist is 20n/m, tensile strength is better for 1521.5MPa than not twisting strength increased by 11.4%, the fracture extension rate is increased by 9%.Composite springs were manufactured by casting method and the influence of weaving process on the properties of the composite spring was studied. It can be shown that the carbon fiber strengthening braid angle of composite spring performance has a crucial impact. When the braided angle is 45 degrees, the spring has the best spring constant. It is showed that when the number of carbon fiber strengthening layer is an even number, the spring constant was significantly better than an odd number.This experiment showed that when the strengthening layer is 4, the spring has the best spring constant; when the strengthen layer increases, the density of the composite spring is gradually stabilized at 1.74g/cm3. |
PDF Full Text Request