Fine Increment Hole-Drilling Method for Residual Stress Measurement, Proposal of a Calibrating Apparatus
Hole drilling is one of the most widely used technique for residual stress measurements, due to its precision and low cost. Standard ASTM E 837  is limited to the uniform distribution of residual stresses, whereas it is well known that residual stresses usually feature high gradient along the depth, particularly if residual stresses are induced by surface treatments such us shot peening. The incremental hole-drilling method can be used to evaluate the not-uniform residual stress distribution as shown by Schajer [2,3]. The strain measurement is repeated at different hole depths to achieve information on the residual stress gradient, from relaxed surface strain. Influence functions for the incremental hole drilling are proposed by Beghini and Bertini  by which the relaxed strain can be evaluated analytically if the residual stress distributions are known for any kind of rosette, hole diameter and elastic material. Valentini  has developed an apparatus able to produce fine increment hole drilling, by means of a high speed air turbine drill automatically controlled. Valentini et al.  used the appartatus to experimentally show the effects on residual stresses measurement by the hole drilling such as eccentricity and sequence of increments steps.
KeywordsResidual Stress Hole Drilling Residual Stress Distribution Residual Stress Measurement Residual Stress Gradient
- 1.AMERICAN SOCIETY FOR TESTING AND MATERIALS, ASTM E 837-95; Standard Test Method for Determining Residual Stresses by the Hole-Drilling Strain-Gage Method. 1996.Google Scholar
- 5.Valentini E., “An automatic system for measuring non-uniform residual stress by the hole drilling Method”, XIII IMEKO World Congress, Torino settembre 1994, 1904–1909.Google Scholar
- 6.Valentini E., Benincasa A., Baggiani M., Brogelli S., “Evolution of high speed drilling technology for evaluating residual stress by hole drilling”, Proc. XXXIV Convegno Nazionale AIAS, Milano 14-17 settembre 2005, 1627–1636. (In italian).Google Scholar