A hybrid technique for residual stress analysis through stress function fitting

Abstract

This work presents a hybrid experimental theoretical technique for residual stresses analysis of mechanical components. It was used the blind hole technique along with the Electronic Speckle Pattern Interferometry (ESPI) method and Airy stress functions for the determination of the principal stress components. Displacement information is fitted in order to extract Airy stress function coefficients. The results demonstrate that this technique is of great utility to determine the average principal stress and local stress gradients.

Pipeline Stress Analysis Through Stress Function Fittings

“…Using a radial interferometer Albertazzi et al (2008) and Fontana (2015), it is possible to measure the radial in-plane displacement field in the region of interest (Figure 1). Instead of releasing the stress field to quantify residual stresses, as in the hole-drilling technique, Cavaco (2011) and Fontana (2015), new stresses are introduced through the indentation producing a local plastic deformation. The radial displacement field around the indentation print is measured and fitted to an appropriate mathematic model and the stress state is modeled around the indented surface.…”

“…A first work was recently presented, Fontana (2015) and Fontana et al (2016) which develops and evaluates a bending stress measurement applied to pipes using instrumented indentation in a minimally invasive way. This paper extends this technique adding the Airy stress analysis, Albertazzi et al (2008), Cavaco (2011) and Cavaco and Brito (2015), to fit the radial displacement data. The measurement system uses a laser interferometer characterized by radial in-plane sensitivity to measure radial displacement data in response to a controlled indented print.…”