New Multiscale Methodology for Evaluating Distributions of Residual Stress in Processed Aerospace Alloys.

摘要

This project focused on the development of a new method for determining residual stress fields in polycrystalline metallic alloys using high energy synchrotron x-ray diffraction measurements and a finite element discretization of the workpiece. At each diffraction volume, the diffraction data provides a link to the single grain scale stresses through pole figures of lattice strain. An optimization method produces the macroscale residual stress for every point in the body that satisfies equilibrium on the macroscale and is simultaneously consistent with the grain scale stress at the diffraction volumes. The method was demonstrated on four different test scenarios: (i) conventional nickel shrink-fit disk (producing a 2D stress field), (ii) a tapered nickel shrink fit disk (producing a 3D stress field), (iii) a titanium shrink fit disk demonstration with hcp material and (iv) a shot peened sample demonstration on an important application. All experiments were conducted at the Advanced Photon Source. The synchrotron radiation and high-throughput area detectors were ideal for proving up the new method.