Pushing modelling limits to protect aircraft engines
Turbine engine rotors or bladed disks are susceptible to vibration-caused problems. Severe vibrations can have detrimental effect on mistuned bladed disks with structural variations as a result of wear or faulty manufacturing. The ingestion of foreign objects into engines and the resulting blade damage is also responsible for failures. Development of on-board SHM tools for rotor blades is therefore a high priority. This was the aim of the EU-funded project UPGRADE (Complex dynamic interactions of nonlinear, multistage and localization phenomena in turbine engines: Development and validation of efficient and accurate modeling techniques). Effective SHM relies on a deep understanding of the underlying physical phenomena to be monitored and their key parameters' correlation to measurable blade damage. Researchers have studied the fundamental physics behind the complex and multistage response of an engine rotor with cracked and/or mistuned blades. As part of a forced response analysis, a numerical code was implemented to produce a database of responses to various vibration frequencies for both tuned and mistuned components. The team's next step was to develop simplified modelling techniques to reduce the runtime of non-linear analysis of bladed disks with damage. Having established the theoretical background required for SHM, the team established a method for crack detection and localisation in mistuned and cracked bladed disks. For this purpose, mock-up blades were tested in a rig designed to experimentally validate accuracy and effectiveness in identifying cracked blades of engine components. UPGRADE delivered key building blocks for an SHM system capable of detecting damage to turbine engine rotor blades. The new techniques for online crack detection will enable critical maintenance and repair decisions leading to augmented operational capabilities. The benefits will also be felt by the aerospace industry in the development of new air vehicles through increased use of modelling and simulations.
Keywords
Aircraft engines, structural health monitoring, bladed disks, severe vibrations, UPGRADE