Structural health monitoring of aero-engines in non-stationary operations

Abstract

With the ultimate goal of rotating machinery diagnosis using Instantaneous Angular Speed (IAS) and Time of Arrival (TOA) signals, this paper provides the theoretical background of non-stationary processes existing in the aero-engines and their monitoring using atypical encoders (e.g. fans, compressors and turbine blades cooperating with the induction sensors, AC and DC generators). The model of TOA signal including aperiodic, periodic and stochastics components has been described. The classical and expert approach to monitoring of operational and structural health parameters (CM, NDT, SHM) of aircraft and its power transmission system has been also described. Finally, the experience of the Tip Timing method used in the Armed Forces of the Republic of Poland is presented. The possibility of structural health monitoring and active controlling of the material fatigue by the aero-engine user through interference in the fuel system adjustment quality has been confirmed. Phase portraits have been used to analyze TOA components in transient state of the engine. Diagnostic criteria and expert algorithms have been verified during active and passive experiments.