Estimation of Elastic Constants in Low Symmetry Materials With In-Situ Neutron Diffraction

Tuesday, October 21, 2025: 2:50 PM
Dr. Nathan Peterson , Los Alamos National Laboratory, Los Alamos, NM
Dr. Daniel Savage , Los Alamos National Laboratory, Los Alamos, NM
Dr. Donald W. Brown , Los Alamos National Laboratory, Los Alamos, NM
Dr. Bjørn Clausen , Los Alamos National Laboratory, Los Alamos, NM
Dr. Aaron Stebner , Georgia Institute of Technology, Atlanta, GA
Dr. Elena Garlea , Y-12 National Security Complex, Oak Ridge, TN
Dr. Sean Agnew , University of Virginia, Charlottesville, VA
Dr. Amy J. Clarke , Los Alamos National Laboratory, Los Alamos, NM
Knowledge of the single crystal elastic constants for a given material is essential for many modeling efforts in materials science and are critical for the measurement of residual stresses from diffraction techniques. Traditionally, these constants were measured with acoustic methods on isolated single crystals, which are difficult, if not impossible, to obtain for certain low symmetry materials (e.g. B19’ NiTi, U-6Nb). An in-direct measurement can be made using in-situ diffraction measurements on polycrystals, which provides a measurement of the stress-strain response at both the aggregate and grain set level. The estimation of the single crystal elastic constants therefore becomes a problem which is inverse of a residual stress measurement. In this work, a combined elastic self-consistent model and whole pattern fitting approach was used to analyze in-situ neutron diffraction data to estimate the elastic constants of low symmetry materials. The robustness of the approach was evaluated through a variance-based sensitivity analysis. An estimation of uncertainty using a Markov Chain Monte Carlo (MCMC) approach will also be discussed.
See more of: Quantifying Uncertainty in Residual Stress Measurements: a Cross-Method Perspective II (Continued)
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