Simulation of Infinite Boundaries When Evaluating Hole-Drilling Calibration Data

Background Effective use of the hole-drilling method for measuring residual stresses depends on the availability of accurate calibration data. A challenge arises when doing finite element modeling because the hole is conceptually drilled into an infinite material, while any practical model must have a finite far boundary. The use of a very distant far boundary provides a better simulation, but makes the required finite element model large and computationally burdensome. Objective The objective is to develop the practical use of an outer ring surrounding the target area of interest that can simulate an infinite far boundary and so allow the use of a more compact and computationally efficient finite element model. Methods Mathematical formulas were developed that specify the material properties of the needed outer ring. These apply to calibration calculations using both the hole loading and thermal loading methods. Results Isotropic loading models work directly for all finite element types and reproduce theoretical expectations to within 0.05%. Deviatoric loading models require some adjustment to fit the finite element model used, after which they can reproduce theoretical expectations to within 0.4%. Conlusions The use of a boundary ring is effective in simulating an infinite boundary when modeling the deformations around a stressed hole. This is useful when computing the calibration coefficients required when making hole-drilling residual stress measurements.

Automated summary

The study aimed to develop a practical method for simulating an infinite boundary in finite element models using an outer ring boundary to create a more compact and computationally efficient model. The research involved developing mathematical formulas specifying the material properties of the outer ring and conducting calibration calculations using different loading models. Results showed that the boundary ring is effective in simulating deformations around a stressed hole, which is useful for computing the calibration coefficients needed for hole-drilling residual stress measurements.