A Procedure for Plasticity Error Correction for Determination of Residual Stresses by the ESPI-HD Method

A Procedure for Plasticity Error Correction for Determination of Residual Stresses by the ESPI-HD Method

L. Lobanov, F.A.P. Fernandes, V. Savitsky

Abstract. The standard strain gage hole drilling method for residual stress determination assumes a linear elastic behavior of the material. However, if the stress level is high, plastic deformation may occur near the drilled hole, resulting in significant errors in the calculation of residual stress. The application of optical whole-field interferometry methods like speckle-interferometry (ESPI) for determining residual stresses allows to gather more information about the stress state of an object compared to the data from resistance strain gauges. Such advantage is achieved by calculating a significantly larger amount of displacement values induced by the hole-drilling. The ESPI-HD method additionally enables automated data analysis and selection of predefined areas with displacements in the vicinity of the drilled hole to determine the plasticity effect without the need of the material’s yield stress. In the present work, an approach is described to determine the plasticity effect without using the yield stress. The approach is based on the fact that plastic deformation in the vicinity of the hole is not uniform. Analysis of stress variation at different sectors near the hole allows retrieving the real stress state. The developed method can significantly reduce errors in the determination of high residual stresses. The influence of materials properties, such as Young and plastic tangent moduli, Poisson ratio and yield stress, on the results obtained by the proposed procedure for plasticity error correction is investigated.

Keywords
Residual Stresses, Speckle-Interferometry, Hole Drilling, ESPI-HD Method, Plasticity Effect

Published online 9/11/2018, 6 pages
Copyright © 2018 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA

Citation: L. Lobanov, F.A.P. Fernandes, V. Savitsky, ‘A Procedure for Plasticity Error Correction for Determination of Residual Stresses by the ESPI-HD Method’, Materials Research Proceedings, Vol. 6, pp 83-88, 2018

DOI: http://dx.doi.org/10.21741/9781945291890-14

The article was published as article 14 of the book Residual Stresses 2018

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

References
[1] ASTM E837-13a, Standard test method for determining residual stresses by the hole-drilling strain-gage method, in Annual Book of ASTM Standards, Am. Soc. Test. Mat, 2013.
[2] Lin Y.C., Chou C.P., Error induced by local yielding around hole in hole drilling method for measuring residual stress of materials, J. Mater. Sci. Tech., Vol.11, 1995, pp. 600–604. https://doi.org/10.1179/mst.1995.11.6.600
[3] Beghini M., Santus C., Valentini E., Benincasa A., Experimental Verification of the Hole Drilling Plasticity Effect Correction, Materials Science Forum, Vol. 681 (2011), pp. 151-158. https://doi.org/10.4028/www.scientific.net/MSF.681.151
[4] Lobanov L., Savitsky V., Residual Stresses Determination with Plasticity Effects by Electron Speckle-Interferometry Hole-Drilling Method, Mat. Res. Proc., Vol. 2, 2017, pp. 389-394. https://doi.org/10.21741/9781945291173-66
[5] Baldi, A., A new analytical approach for hole drilling residual stress analysis by full field method, J. Eng. Mater. Technol., Vol. 127, No. 2, 2005, pp. 165–169. https://doi.org/10.1115/1.1839211
[6] Lobanov L., Pivtorak V., Savitsky V. and Tkachuk G., Technology and Equipment for Determination of Residual Stresses in Welded Structures Based on the Application of Electron Speckle-Interferometry, Materials Science Forum, Vol. 768, 2014, pp. 166-173.