METHOD OF DETERMINING OF FORMS OF RESONANT VIBRATIONS SHAPES OF BLADES OF GAS TURBINE ENGINE BY SPECKLE INTERFEROGRAM Patent UA 103068 (2015) 103

The method is designed for contactless and high-precision study of the dynamic characteristics (natural frequencies and vibration modes) of turbine and compressor blades in gas turbine engines. Operating principle: Electronic speckle interferometry (time averaging) is used. Laser radiation forms a speckle pattern on the surface of a vibrating blade. Analysis of interference fringes allows for highly accurate recording of amplitude-frequency characteristics and nodal lines at resonance.
Novelty: Improved noise immunity and accuracy of coherent optical measurements under real experimental conditions, enabling the identification of hidden defects and refinement of finite element models of blades.