Structural Design and Optimization of Piezo-Activated Morphing CFRP Fan Blades

Abstract Modern aeronautical engines and their fans are currently conceived for optimal performance at a design point defined by the conditions of the dominant flight phase. Due to the resulting fixed blade geometry, engine efficiency is reduced during off-design conditions. A switch to shape-adaptive blades enables the adjustment of the geometry to prevailing conditions, increasing efficiency. Therefore, a methodology was developed for the design of piezo-activated morphing metallic engine blades within the Sustainable and Energy-Efficient Aviation SE2A Cluster of Excellence. To cover more off-design conditions, it is necessary to increase the morphing deformations. This paper introduces an extension of the methodology that enables the design of blade bodies from plies of carbon fiber-reinforced polymers. The goal is to use the anisotropic material properties of these composites to increase the achievable morphing deformations. A genetic algorithm is used to optimize the carbon fiber orientations of two fan blade architectures to maximize the morphing related change in turning angle or stagger angle. These tailored morphing composite fan blades achieve higher angular changes at a lower mass compared to titanium alloy blades.