Generating matrices of the foundation structure of a rotor system from test data

In a rotor system, the structure beyond the rotor and bearings, known as the foundation, can have a significant effect on the dynamics of the rotor. A common practice is to ignore this foundation effect or to use a very simplified method to account for the foundation flexibility. To overcome the limitation of such simplifications, this paper provides a general procedure to include the foundation effects using modal analysis techniques and measured frequency response functions of the foundation structure. From this test data, mass, damping and stiffness matrices are constructed. These matrices are then assembled with the finite element model of the shaft to form the overall rotor system model.