NONLINEAR VIBRATION ANALYSIS OF GAS TURBINE BLADINGS WITH SHROUD COUPLING

Rotating blades are subjected to vibrations caused by excitation forces due to a non-homogeneous pressure field of the fluid. Therefore, damping devices like tip shrouds are implemented which reduce the vibrational amplitude and apply additional stiffness and damping to the structure. To predict the resulting vibration response and stresses, a three dimensional contact model has been developed to determine the friction forces. The resulting equations of motion are solved in the frequency domain. The developed method has been implemented in a non-linear forced response code called DATAR(1) designed for the gas turbine division of Siemens Energy. In this paper, the transfer of common Finite Element models of bladings with shrouds or underplatform dampers to the DATAR code is presented. A mapping procedure based on Finite Element shape functions is used to couple the model with the regular contact grid used in the non-linear vibration analysis performed with the DATAR code. As a practical example, the vibration behavior of a gas turbine blading with interlocked shrouds is investigated with the developed method