HCF and Mistuning Detection

During the course of operation the blades of a blisk are altered by erosion, fatigue, and FOD. In the case of more significant blade damage the blade may need to be blended to restore its strength. These changes can result in rotor mistuning, allowing for more damaging modes to be supported in the rotor, leading to high cycle fatigue and ultimately rotor failure. Prime, with team partner Virginia Tech, will adapt the existing FOCIS technology platform to detect the vibrations of the rotor blades to prevent the onset of high cycle fatigue. This will be done by expanding the FOCIS probes native ability to perform time of arrival measurements and instantaneous blade tip velocity measurements. In the proposed configuration, a multi-beam variant of the FOCIS probe will be developed allowing for simultaneous monitoring of a blades motion at multiple locations. By comparing the blade motions against a known good standard (e.g. a factory tuned rotor) the degree of mistuning can be assessed. Work on the project will include: Refinement of the probe system to use additional beams Theoretical analysis to determine the optimal placement of the beams Experimental validation using the Virginia Tech blade vibration and flutter research rig