Development Technology for a Stepped Diameter TMC Shaft

This proposal is to develop and demonstrate technologies for a VAATE TMC tapered counter-rotating shaft. The GEAE VAATE engine incorporates counter-rotating inner/outer shafts. The inner shaft has a long length, relatively small diameter and is tapered along its length. To satisfy dynamic and torsion requirements (high frequency along with high torsion capability) it employs a high stiffness, high torsion strength, and low-density TMC material. Issues associated with using TMCs for such an application have not been studied; i.e., (1) arrangements and methods for fiber/matrix architecture control and consolidation processing in a varying cross section tapered TMC shaft, (2) related process and performance modeling, (3) vibration response and strength prediction trade studies, (4) crack growth rate and toughness as a function of TMC fiber architecture, and (5) fiber bridging effects during ply layup, HIP processing and cyclic torsion operation. Phase I will study these issues, develop concepts and fabricate a stepped diameter TMC part to demonstrate capability for successful design, manufacture and implementation of a counter-rotating TMC shaft. Phase II will provide detailed analytical derivations, development and prototypical device demonstrations as well as develop a technology transition plan for future systems and commercial ventures.