Rotordynamic Analyses Using Finite Element Method

The ability to perform critical frequency and forced response analyses is a vital tool for designing and troubleshooting rotordynamic systems. These analyses can be a challenge due to the wide variety of components found in rotordynamic systems. There are a variety of methods that can be used to perform these analyses. The finite element method is one method that can be used to perform these analyses.
A finite element approach to rotordynamic analyses is presented in this thesis. First, the finite element model is developed. The equations of motion that are used to analyze the finite element model are developed. Next the development of a MATLAB based rotordynamic tool incorporating this method is presented. The features of this tool, including degree-of-freedom coupling, multiple rotor systems, and the inclusion of tilting pad bearings with full coefficients, aerodynamic cross couplings, thrust bearings, flexible bearing supports, flexible couplings, and the stiffness properties of disks in the model, are presented as well as improvements that have been made to the efficiency of the program. Finally program is verified by comparison to a case study for both stability and forced response analyses and validated with a different case study. The verification case is a classic eight stage compressor rotor model that has been widely used as a test case for other industry software. The validation case study is a ROMAC test rig used to study stability. In both cases, differences of less than 5% were found. These cases illustrate the accuracy of the methods developed in this thesis.