Development of a Set of Equations for Incorporating Disk Flexibility Effects in Rotordynamic Analyses

Rotordynamic equations that account for disk flexibility are developed. These equations employ free-free rotor modes to model the rotor system. Only transverse vibrations of the disks are considered, with the shaft/disk system considered to be torsionally rigid. Second-order elastic foreshortening effects that couple with the rotor speed to produce first-order terms in the equations of motion are included. The approach developed in this study is readily adaptable for usage in many of the codes that are currently used in rotordynamic simulations. The equations are similar to those used in standard rigid disk analyses but with additional terms that include the effects of disk flexibility. An example case is presented to demonstrate the use of the equations and to show the influence of disk flexibility on the rotor dynamic behavior of a sample system.