State-of-the-art dynamic analysis for non-linear gas turbine structures

An accurate and robust method has been developed for the general multiharmonic analysis of forced periodic vibrations of bladed discs subjected to abrupt changes of elastic and damping properties at contact nodes located on the interfaces of the components. The approach is based on an analytical formulation of friction contact interface elements which provides exact expressions for multiharmonic forces and stiffness matrices of the elements. The analytical formulation overcomes the numerical difficulties associated with searching for a solution of the non-linear equations, which have been inherent so far for the considered systems, and provides a breakthrough in the analysis of the non-linear forced response of bladed discs and other structures with gaps and friction interfaces. An effective reduction method is reported that allows the size of the resolving equations to be decreased to the number of DOFs (degrees of freedom) at the contact surfaces, while preserving completeness and accuracy of the whole large-scale model. Numerical investigations demonstrate the outstanding properties of the proposed approach with respect to computational speed, accuracy and stability of calculations for practical gas-turbine structures.