Three-Dimensional Stress Analysis of a Fiber-Reinforced Composite Thruster Blade

Stress calculations were carried out for a proposed fiber-reinforced composite thruster blade. The composite blade is constructed using multiple layers of braided fiber in a thick-shell skin layer; the core is filled with foam-type material and uses shear webs for internal support. The objective of this paper is to explore the rotating blade hydrodynamic design constraints of a typical composite blade by performing a 3-D finite element analysis. Two salient features are revealed from the numerical results: (1) maximum tip deflection of the composite blade can be quite large; (2) maximum through-the-thickness tensile stress in the skin layer thickness direction could become critical for higher loadings. It is demonstrated in the sample calculation that a sandwich-type composite blade can provide not only a means of weight-savings, but it also can have excellent structural stiffness and strength properties through proper geometric and material design.