The Rolls-Royce Mechanical Test Operations Centre (MTOC) near Berlin performs mechanical and structural evaluation of gas turbine components during development, production and service life. High cycle fatigue (HCF) testing of engine components at their various mode frequencies is the primary vibration test type to ensure the reliability of the components. The Finite Element models enable prediction of eigenfrequencies and mode shapes of engine components, and also calculate stress and expected lifetime of each component.
The MTOC vibration testing capabilities for HCF involve the following test rigs and equipment: fatigue testing of large fan blades, hot HCF testing of turbine blades and HCF testing of compressor blades and vanes. For HCF testing, several technologies can be used to excite the engine parts including a constant airjet (flutter), chopped airjet (pulsed air), electromagnetic and piezoelectric shaker. These four technologies cover the resonance range of engine components up to 40 kHz.
The Rolls-Royce MTOC uses m+p VibControl controllers which are optimized for HCF dwell testing with phase tracking for components with low damping. They support both m+p VibPilot and m+p VibRunner acquisition hardware. To achieve HCF tests for higher modes above 20 kHz, the high-frequency option was installed. With this system, the phase lock-in and phase tracking works the same at 30 kHz as the previous system worked at 3 kHz.
The installation of several high-frequency vibration controllers from m+p international within the Rolls-Royce MTOC has not only helped improve the quality of HCF testing of engine blades and vanes, as well as improve overall test stability and quality, but also ensured the required setup time was considerably reduced.
Download the 3-page “Blade Runners” Article, published in the 2016 Showcase of the Aerospace Testing International magazine.