A study for stainless steel fan blade design with metal foam core

The pursuit for cheap, low-density and high-performance materials in the design of aircraft engine blades raises wide-ranging challenges to the materials and structural design engineers. Traditionally, these components have been fabricated using expensive materials such as lightweight titanium alloys and polymer composite materials composites. The present study investigates the use of a sandwich foam fan blade made of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation-hardened 17-4 stainless steel with high strength and high toughness. The stiffness of the sandwich structure is increased by separating the two face sheets by a foam core. The resulting structure possesses a high stiffness while being lighter than a similar solid construction. Since the face sheets carry the applied bending loads, the sandwich architecture is a viable engineering concept. The material properties of 17-4 precipitation-hardened metal foam are briefly reviewed to describe the characteristics of the sandwich structure for a fan blade application. Vibration characteristics and design criteria on the 17-4 precipitation-hardened metal foam core sandwich blade design with different combinations of skin thickness and core volume are presented with a comparison to a solid titanium blade.