Structural Dynamics of Shroudless, Hollow, Fan Blades with Composite In-Lays

Abstract

Structural and dynamic analyses are presented for a shroudless, hollow, titanium fan blade proposed for future use in aircraft turbine engines. The blade was modeled using the Lewis Research Center's Blade Structural Analysis Computer Program (COBSTRAN). COBSTRAN is an integrated program consisting of mesh generators, composite mechanics, NASTRAN, and pre- and post-processors. Vibration, and impact analyses are presented. The vibration analysis was conducted with COBSTRAN. Results show the effect of the centrifugal force field on frequencies, twist, and blade camber. This program uses the geometric model and modal analysis from the COBSTRAN vibration analysis automatically to determine the gross impact response of the fan blades to bird strikes. The structural performance of this blade is compared to a blade of similar design but with composite in-lays on the outer surface. Results show that the composite in-lays can be selected (designed) to substantially modify the mechanical performance of the shroudless, hollow, fan blade.