Abstract: For simulating the structure of spline coupling in the low pressure rotor of a typical high bypass ratio turbofan engine，a mechanical model was developed and a test rotor system connected with a spline coupling was established. Appropriate support stiffness was selected through dynamics calculation in order to meet the first，second critical speed of the design requirements. Theoretical analysis and experimental research were conducted about the effects of tightening torque of the axial nuts on the connection stiffness of the spline coupling and on the dynamic characteristics including critical speed，vibration modes and unbalance responses of the rotor system. The results indicate that the tightening torque of the axial nuts increase the connection stiffness of the spline coupling with obvious nonlinearity. With increasing the tightening torque from [60N?m] to [120N?m]，the growth rates of the first-order and second-order critical speed of the rotor system are 1.23% and 0.51%，respectively，and the amplitudes of the corresponding unbalance responses increase to varying degree，while the corresponding vibration modes are basically unchanged. Changing axial and circumferential positions of unbalance value can result in different amplitudes and rate of changes of unbalance response.

Key words: Spline coupling；Connection stiffness；Tightening torque；Dynamic characteristics

摘要： 针对大涵道比涡扇发动机低压转子中套齿式刚性联轴器结构，建立了套齿联轴器的力学模型和通过套齿联轴器连接的试验转子系统，通过动力学特性计算选择合适的支承刚度，以满足一阶、二阶临界转速的设计要求。理论分析和试验研究了轴向螺母拧紧力矩对套齿连接刚度以及对转子系统的临界转速、振型和不平衡响应等动力学特性的影响规律。结果表明:轴向螺母拧紧力矩会增大套齿联轴器的连接刚度，并且呈现明显的非线性特征。随着轴向螺母拧紧力矩从[60N?m]增大到[120N?m]，转子系统的一阶与二阶临界转速增长率分别为1.23% 与0.51%；对应的不平衡响应幅值不同程度地增大；而对应的振型基本保持不变。改变不平衡量的轴向与周向位置会导致不平衡响应幅值大小及其变化率有所不同。

关键词: 套齿联轴器；连接刚度；拧紧力矩；动力学特性