Tactical Missile Technology

As the widely used connection in the low-pressure rotor of aeroengine, rigid spline joint will transfer multi-axial load such as axial force, bending moment, shearing force and torque at work. Therefore,multi-axial load will change contact states of centering surfaces, end faces and spline surfaces, which results in complex change law of the structure stiffness. To solve this problem, based on the contact finite element method, a nonlinear simulation model of spline joint with multiple contact surface is established under multiaxial load. Two quantitative evaluation parameters, the sensitivity of equivalent stiffness to the contact surface and the ratio of contact state of the contact surface are proposed. According to these two parameters, the nonlinear characteristics of the stiffness of the spline joint, and the change law of the contact state of the contact surface are revealed, with key influencing factors. The results show that the incensement of external load results to the loss of the equivalent stiffness of the spline joint. During this process, the contact state of each contact surface changes. Centering surface B is the greatest influence on spline joint. End face B and centering surface A are the main reason of the nonlinear change of the stiffness of the spline joint. The contact of meshing spline surface can improve the connection stiffness, without effect on the nonlinear characteristics.The stiffness of the spline joint increases with the increase of the dimension tolerance of centering surfaces,preload and torque of the nut.