Plasticity Effects in the Hole-Drilling Residual Stress Measurement in Peened Surfaces

Abstract

The incremental hole-drilling technique (IHD) is a widely established and accepted technique to determine residual stresses in peened surfaces. However, high residual stresses can lead to local yielding, due to the stress concentration around the drilled hole, affecting the standard residual stress evaluation, which is based on linear elastic equations. This socalled plasticity effect can be quantified by means of a plasticity factor, which measures the residual stress magnitude with respect to the approximate onset of plasticity. The observed resultant overestimation of IHD residual stresses depends on various factors, such as the residual stress state, the stress gradients and the material's strain hardening. In peened surfaces, equibiaxial stresses are often found. For this case, the combined effect of the local yielding and stress gradients is numerically and experimentally analyzed in detail in this work. In addition, a new plasticity factor is proposed for the evaluation of the onset of yielding around drilled holes in peened surface layers. This new factor is able to explain the agreement and disagreement found between the IHD residual stresses and those determined by X-ray diffraction in shotpeened steel surfaces.

Nanoscale residual stress depth profiling by Focused Ion Beam milling and eigenstrain analysis

“…A subset of this family are techniques that are semidestructive, in that they involve minimal modification of sample surface e.g. by 'blind' or through hole drilling [16,17,18], ring-core [19,20], cantilever deflection [21], slot cutting [22] slitting [23,24] and nanoindentation [25,26,27]. Material removal at the macroscopic scale can be performed by conventional tools (e.g.…”

Residual stresses in cold-formed steel members: Review of measurement methods and numerical modelling

“…For non-uniform residual stress determination, the inverse problem associated to hole drilling becomes even more complex when plasticity effects are considered. Hence, only equi-biaxial stress states, as those usually produced by shoot peening, have been considered for plasticity corrections and non-uniform in-depth distributions [132]. Artificial neural networks have been successfully applied to solve the inverse problem of plasticity correction in peened surfaces [133].…”

Recent Advancements in the Hole-Drilling Strain-Gage Method for Determining Residual Stresses

“…Nobre et al [21] provide a similar approach for the estimation of the plasticity factor f. The material characteristics are taken into account by measuring the variation of Vickers hardness, which estimates the material strain hardening due to the increase of plastic deformation.…”

“…Drilling a hole locally modifies the geometry of the specimen and the stresses around the hole increase by the concentration factor of the discontinuity. It is possible to adopt a stress correction methodology for a uniform stress field and the blind hole case [20][21][22].…”