Measurement of Non-Uniform Residual Stresses Using the Hole-Drilling Method. Part I—Stress Calculation Procedures

TLDR

The study evaluates several procedures—Incremental Strain, Average Stress, Power Series, and Integral—for calculating non‑uniform residual stresses from hole‑drilling strain‑relaxation data. The authors present theoretical error estimates for different stress fields and introduce variable transformations that decouple the stress/strain equations to simplify numerical solutions. They find that the Incremental Strain and Average Stress methods have theoretical shortcomings and are essentially approximations of the Integral Method.

Abstract

The Incremental Strain, Average Stress, Power Series, and Integral methods are examined as procedures for determining non-uniform residual stress fields using strain relaxation data from the hole drilling method. Some theoretical shortcomings in the Incremental Strain and Average Stress methods are described. It is shown that these two traditional methods are in fact approximations of the Integral Method. Theoretical estimates of the errors involved are presented for various stress fields. Also, some simple transformations of stress and strain variables are introduced so as to decouple the stress/strain equations and simplify the numerical solution.