Research On Interference Fit Of CFRP Shaft Tube And Metal Shaft Head

The shaft part is a common part in mechanical equipment,which is usually made of metal material.In the circumstances of high-speed rotation,the shaft made of metal material will not only bring large noise and vibration effect,but also result in high energy cost,in this case,lightweight of drive shaft takes a good way to reduce noise and save energy.The drive shaft made of Carbon Fiber Reinforced Plastics(CFRP)has characteristics such as high specific strength,high specific stiffness,high specific modulus,excellent fatigue resistance and vibration damping performance.It is increasingly used in various transmission systems.Carbon fiber composite tubes are manufactured by additive manufacturing.Compared to metal shaft,carbon fiber composite tubes have poor machinability and assemblability.Therefore,carbon fiber composite tubes and metal shaft head are often connected to maintain the properties of good assemblability in metal shaft head.There are several connection methods of CFRP and metal parts such as adhesive connection,mechanical connection and new type connection methods.Compared to the adhesive connection and mechanical connection,the interference-fitting joint has the characteristics of no destruction of fiber continuity,unified stress distribution and high connection efficiency as a new type of connection methods for CFRP and metal's connection,so,the design and evaluation methods of the interference-fitting joint between the CFRP shaft tube and the metal shaft head has great engineering significance.Therefore,the interference-fitting joint of CFRP shaft tube and the metal shaft head under the torsion load was studied in this paper.From the analysis of stress state in CFRP shaft tube and metal shaft head,the effects of carbon fiber stacking schemes,magnitude of interference on the assembly force and failure torque of interference-fitting joint was studied in the paper,the design and evaluation method of interference-fitting joint between CFRP shaft tube and metal shaft head was put forward through theory,finite element simulation and experimental methods.The main contents of the full text are as follows:Firstly,on the basis of the materials mechanics,the stress distribution of the CFRP shaft tube and the metal shaft head were analyzed respectively by the theory of thick-walled cylinders.According to the classical lamination theory,the main factors which affect the performance of the joint between CFRP shaft tube and metal shaft head were determined as the hoop rigidity of CFRP shaft tube and interference value.Secondly,an interference fitting finite element model of CFRP shaft tube and metal shaft head were established through ABAQUS on the basis of the design requirements of the CFRP driveshaft.The assembly and torsion process of the interference-fitting joint were simulated respectively.The contact surface stress index CPRESS was used to observe in assembly process,the stress index Mises and the failure index TSAIW was used to judge failure extent respectively for the metal shaft head and the CFRP shaft tube.It is concluded that the maximum structure stress of the joint after the assembly process occured in the innermost fiber layer and the maximum structure stress of the joint during the torsion process occured in the angular position of the stepped surface.The stress distribution of the contact surface was slightly increased along the assembly length.Then,the effects of carbon fiber stacking schemes,interference value on the assembly force and failure torque of interference-fitting joint was researched through the finite element simulation analysis and experimental tests.It is concluded that in different stacking schemes,the layer angle of CFRP shaft tube has a greater influence on the joint connection than the stacking sequence.The larger the layer angle,the better the joint connection of the interference-fitting joint.But oversized angle lay-up has relatively insignificant improvement in the connection performance.If choosing different angles for lay-up,the small angle should be put in the middle layer in order to get lower damage and higher safety.While changing the interference value of the interference-fitting joint,the maximum assembly force and the torsion were generally linear with the interference values,the failure extent of the CFRP shaft tube and the metal shaft head was also increased with it.The contact surface stress along the assembly length was similar,showing a maximum value.Finally,on the basis of the above conclusions,the design method of interference-fitting joint between CFRP shaft tube and metal shaft head was summarized,which laid the foundation for a new connection type of CFRP shaft tube and metal shaft head.