Abstract: A hybrid turbine blade and method of fabrication, comprising a shank portion and an airfoil portion. The airfoil portion comprising a composite outer structure having a recess formed therein and an alternating stack of at least one composite section and at least two insert sections disposed in the recess. The outer composite structure and the at least one composite section having a first density. The at least two insert sections having a second mass density, which is less than the first mass density. The composite outer structure and the alternating stack of at least one composite section and at least two insert sections together define an airfoil portion that meets all mechanical load carrying requirements of said hybrid turbine blade such that no load transfer needs to occur through said at least two insert sections.

Abstract: An airfoil structure includes a composite core including a triaxial braid, wherein the triaxial braid includes a longitudinal axis, a first bias fiber extending in a first bias direction at a first bias angle to the longitudinal axis, a second bias fiber extending in a second bias direction at a second bias angle to the longitudinal axis, and an axial fiber extending in a direction parallel to the longitudinal axis. The airfoil structure further includes an outer layer substantially surrounding the composite core, wherein the outer layer includes a plurality of unidirectional prepreg layers.