Towards Efficient Torsional Fatigue Testing: Designing Flexible Two-Dimensional Compound Loading Machines

Abstract

Torsional fatigue is a critical design consideration for many rotating components in aerospace, power generation, and other industrial applications. Traditional uniaxial fatigue testing rigs are not well-suited for evaluating materials under combined torsional and axial loading. This paper explores options for designing a flexible, two-dimensional loading frame to enable efficient torsional fatigue testing with superimposed axial loads. Key design criteria evaluated include load capacity, alignment, stiffness, frame materials, and modularity. Three design concepts are presented and evaluated based on finite element analysis and other trade studies. The parallel four-bar linkage concept is identified as the leading candidate, with several modularity enhancements. Design recommendations are provided along with areas for future work to mature the design towards prototype fabrication and experimental validation.