Lightweight Design Of Composite Transmission Shaft For Truck

The lightweight design of automobile is one of the main means to achieve the goal of energy-saving and emission reduction.Considering the more than 200 million cars in China,the energy-saving and emission-reducing effect brought by every kilogram of vehicles is attractive enough.In this paper,a carbon fiber composite transmission shaft model with nested-toothed composite connection structure is established based on the design concept of composite steel-carbon fiber drive shaft and the steel transmission shaft,and the lightweight design of carbon fiber composite shaft assembly is realized through a series of optimized design of carbon fiber composite shaft tube.In this paper,the characterization of stress-strain relationship of anisotropic materials,the mechanical properties of classical laminates and the failure criteria of composite materials are introduced.Based on this,the general principles of laminated composite plates are expounded.Then the mechanical properties of the selected T300 / 5208 composites were tested and the basic properties of the composites were obtained.The three-dimensional solid model and the finite element analysis model are established based on the original steel transmission shaft.The accuracy of the finite element model of the drive shaft assembly is verified by comparing the first six order modal characteristics of the drive shaft assembly obtained by simulation analysis and test,which provides a foundation for the design of the transmission shaft with carbon fiber composite material.Three new types of transmission shaft structure of carbon fiber composite material are proposed,which are composite steel-carbon fiber shaft pipe transmission shaft,shaft fork-shaft pipe rectangular tooth meshing connection and nested-tooth composite connection.After considering all kinds of factors,the nested-toothed composite connection mode is finally determined as the structural connection scheme of the carbon fiber composite transmission shaft.Through a series of simulation and analysis work,the number of rectangular teeth,the length of rectangular teeth and the size of the nested part of the shaft tube in the nested-toothed composite connection scheme are worked out.Finally,the different proportion schemes of each ply angle are explored,and the simulation results are analyzed by ANOVA,the significant relationship between different ply angles to each factor is determined according to the F-significance test.Based on this,the proportion of each ply angle in the drive shaft of carbon fiber composite material is determined,and the preliminary laying scheme is determined considering the general laminating principle of laminates.In the free dimension and dimension optimization stage,the thickness of the grid element is taken as the design variable,and the first-order modal natural frequency of the transmission shaft,the maximum vonMises stress value of the steel shaft fork and the failure index of the carbon fiber composite pipe are taken as the constraints,the optimization model of the transmission shaft is established based on the volume of the carbon fiber composite shaft tube.Then the total number of layers and the ply angle of each layer of the drive shaft of carbon fiber composite material are obtained.In the optimization stage of laying sequence,the optimal model is established with the maximum vonMises stress value of transmission shaft steel as the design objective,taking the lamination sequence as the design variable and taking the manufacturing restriction of composite laminates as the constraint.After the simulation iteration,the lamination scheme of the final carbon fiber composite transmission shaft is determined.By comparing the original steel drive shaft with the carbon fiber composite material drive shaft assembly,the results show that under the condition of satisfied the performance requirements,the weight of the drive shaft assembly is reduced by 34.41%,the moment of inertia is reduced by 36.29%,and the lightweight design of the transmission shaft is realized.