Advanced Non-Destructive System to Characterize Subsurface Residual Stresses in Turbo-machinery Components

Manufacturers of aerospace propulsion systems are well aware of the positive effects of compressive residual stress (RS) fields on turbo-machinery components in terms of improved fatigue life and durability. Tensile RS, however, can cause unfavorable conditions which may lead to premature failure during operational usage. Thus, the industry objective is to capitalize on compressive RS and prevent or minimize tensile RS at critical locations of engine components but this requires a new NDE/I capability. The Proto Team intends to exploit high energy x-ray diffraction (HEXRD) technologies and demonstrate feasibility for measuring RS distributions non-destructively at subsurface depths in a high-strength aerospace material. Initial experimentation will be performed on laser-peened titanium as the basis for establishing feasibility. The related challenge in this effort is to define and design a small transportable system that can be installed in a factory or depot setting while retaining the depth and resolution performance of the much larger research systems. The Proto Team will capitalize on the experimental research of Iowa State University into HEXRD for measuring subsurface RS and Proto?s expertise in developing, fielding and delivering low-energy, highly portable XRD systems. The Metal Improvement Company will provide Ti-alloy LSP specimens and modelling support.