A mathematical model for squeeze film dampers is developed, and the solution results are compared with data from four different test rigs. A special feature of the analysis is the treatment of several different types of end seals and inlets, with inlet feedback included. A finite difference method is used to solve the Reynolds equation, with a banded matrix inversion routine. The test data are taken from a new high-speed free-rotor rig, and from three previously tested controlled-orbit rigs.

A mathematical model for predicting spline coupling induced nonsynchronous rotor vibrations is developed, and the predictions are compared with data from a rotor dynamics test rig. The special feature of the spline model is the characterization of the friction forces that are produced at the mating spline teeth surfaces and subsequent calculation of the internal damping coefficients. The spline internal damping and the r esulting rotor instabilities are predicted for four different spline configurations and the solution results are correlated with measured data from a gas turbine rotor simulator test rig.

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A computation technique has been developed at Pratt & Whitney Aircraft (P&WA) in which localized dynamic flexibilities in an assembled rotor or case can be rapidly determined from experimental mode shape and frequency data. A dynamic mathematical model of the structure is developed with empirical flexibility terms assigned to mechanical joints such as flanges, splines, couplings, etc. The vibratory response of the structure is measured in laboratory tests and compared with calculated values. Agreement between calculated and experimental mode shapes and frequencies is obtained by a computerized random search technique, which determines the flexibility terms that produce the best match between experimental data and calculated values for all of the vibration modes compared. The technique was developed for rotor critical speed applications, but it may be applied to any simple or complex beam type structure.