Description: Stress analysis of a GT engine fan shaft was performed for IN718 and Ti. A FE package NISA gave stiffness for unit radial and tangential loads. Results obtained with IN718 were compared with an earlier study by SNECMA. An extension of the study for weight reduction was done with Ti material parameters. The design was adapted to simplify a spring bearing mount for the HP (#3) bearing.

A convoluted spring bearing mount suggested by SNECMA was redesigned using the results for the conical fan shaft to give a more gradual stress distribution. Such a structure would be less likely to yield in LCF and catastrophic failure modes. Comparison between computed results and tabulated results for conical shells was attempted.

Results depended on loading and point of application and mounting. For instance, the fan shaft was fixed on the main rotor and a force applied to the rim and vice versa. Variation in the number of nodes and order of approximation also affected the results. Regions of maximum stress were shown in contour plots, while displacement studies gave modes of deflection.

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