Design Of CFRP Transmission Shaft

Carbon fiber reinforced plastic (CFRP) transmission shaft is higher specific stiffness and strength, superior fatigue characteristics as well as excellent corrosion resistance over metals, composite transmission shaft also offers superior vibration damping, less noise, better safety. Therefore, the study of CFRP transmission shaft has important significance.Wholeness shaft and assembling shaft are two kinds of CFRP transmission shaft's manufacturing method according to the structural forms. The wholeness can be produced by injection molding with short fiber or weaved and cured with continuous fiber. The transmission shaft of assembling type is assembled into an entity by two or more components. It is widely used due to its simple making process and good mechanical properties. The research object of this paper is the assembling carbon fiber transmission shaft.Assembling transmission shaft is mainly constituted by metal components and carbon fiber tube. The connection between carbon fiber and metal components is a key to this article.According to the advantages and disadvantages of frequently-used connection method of the composite materials and metal, mixed connection method (with both glue connection and mechanical connection) was studied during the design of the transmission shaft. Based on the glue connection experience formula and ANSYS analysis results, the best length of connection, and the shear strength of glue. Screw was used in the mechanical connection. Its diameter, margin, interval and linewidth etc. were calculated and analyzed respectively. The result of all the parameters could reach the torsional strength.Design of carbon fiber tube is another key to this paper. Carbon fiber tube is different to traditional metal in design methods, It contains material design such as component materials, layer direction, etc..Commonly carbon fiber tube is thin-wall tube component and can be regarded as a kind of laminated hardened components, so the laminated plate design theory is applicable to carbon fiber tube. When transmission shaft is working, it mainly bears torque. So the carbon fiber tube must have sufficient torsional strength and torsional rigidity. Carbon fiber tube structure design includes fibers orientation angles, stacking sequences, layers thicknesses and number of layers. The fibers orientation angles' effect to the torsional strength and torsional rigidity is analyzed in this paper by finite element software ANSYS and Tsai-Wu stress criterion. Carbon fiber tube is produced by filament winding process, because it has high efficiency and gets the required performance for the products in the maximum way. Combined with ANSYS analysis results, the characteristics of filament winding process and the demand of number of layers on connection parts,the structural parameters of carbon fiber tube were obtained including the fibers orientation angles, stacking sequences, layers thicknesses and number of layers. In order to verify the design methed of the drive shaft, test components were produced. Then static torsion test and torsion fatigue test were done. The test results were generally consistent with the prediction of critical damage torque.The result of this paper has reference value to CFRP transmission shaft design.