21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-5.1.4

FINITE ELEMENT MODELING AND EXPERIMENTAL STUDY OF A GAS TURBINE ENGINE BLADE UNDER BIAXIAL LOADING

Xie M., Balan M., Frey N., Brown J.*, Terborg G.*
AdTech Systems Research Inc., U.S.A.; *Air Force Research Lab., U.S.A.

Keywords: finite element modeling, experimental study, gas turbine engine blade, biaxial loading

Gas turbine engine blades are subjected to both radial centrifugal force and transverse excitation under operating conditions. It is very difficult to perform fatigue test on an engine blade in the laboratory because of this biaxial loading condition. In the present study, a simple approach for high cycle fatigue testing of gas turbine engine blades under biaxial loading is proposed. A radial force is applied to the blade to simulate the centiifugal force due to rotation, while a transverse fatigue loading is applied to simulate the vibration of the blade. A three-dimensional finite element analysis was used in the design and optimization of this biaxial loading mechanism. Several important experimental parameters were investigated, including the gripping design at the tip of the blade, the flexible connection between the blade and the test frame, and the application of the transverse vibratory loading. A four-post test frame was constructed to implement the biaxial loading mechanism. A vertical actuator on the frame was used to apply the radial force, while a second actuator was installed horizontally at the side of the frame, to apply the vibratory load to the test specimen. The stress states in the blade specimen, obtained from strain gages, compared well with the finite element results.

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