Simulation of Engine Blade Tip-Rub Induced Vibration

An analysis has been developed to simulate the time-transient vibratory motion of a general configuration engine turbomachinery free-standing blade when subjected to in-service blade-on-casing tip-rub events. The analysis imports the at-speed stress-stiffened blade stiffness matrix and lumped mass matrix from a finite element model of the actual blade. Formulation and computational approaches are presented. Correct characterization of the blade tip-surface rub mechanics tribology models necessitates using empirical information that is currently being acquired from single-blade spin-pit tests now in progress in a parallel companion phase of this research. Output results for validation cases are presented. The analysis efficiently simulates complete transients involving multiple successive incursions (blade on casing hits), tracking the blade tip contact force distribution and blade motion throughout the simulated time frame including blade motion during, between and after successive casing hits.