# Review of “Revealing systematic errors in hole drilling measurements through a calibration bench: the case of zero-depth data”

Marco Beghini, Tommaso Grossi, Ciro Santus, Emilio Valentini, Michael B.

Prime, László Tóth

► To cite this version:

Marco Beghini, Tommaso Grossi, Ciro Santus, Emilio Valentini, Michael B. Prime, et al. Review of “Revealing systematic errors in hole drilling measurements through a calibration bench: the case of zero-depth data”. 2023. hal-04166396

HAL Id: hal-04166396

https://hal.science/hal-04166396

Submitted on 16 Oct 2023

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Identifiers

Open Review

OAI hal-04166396v1

Reviewed Article

DOI 10.46298/jtcam.10080

Licence

CC BY 4.0

©The Authors

# Review of “Revealing systematic errors in hole drilling measurements through a calibration bench: the case of zero-depth data”

©Marco BEGHINI<fnref n="1" />, ©Tommaso GROSSI<fnref n="1" />, ©Ciro SANTUS<fnref n="1" />, Emilio VALENTINI<fnref n="2" />,

©Michael B. PRIME<fnref n="3" />,<fnref n="4" />, and ©Lazslo TOTH<fnref n="4" />,⁵

## Review of version 1

Permalink: hal-03721795v1

**Authors** We sincerely thank the Editors and the Reviewers for their efforts and their contributions to this paper. On behalf of our team, we extend our best wishes for a joyous holiday season and a successful new year.

## Reviewer 1 (Michael PRIME)

**Reviewer** This is very nice work and very well presented. All of the technical work is well supported and free from technical errors. No revisions are required. The most intriguing aspect of this work is the 4th conclusion with the possibility for in situ error identification and direction. I trust that the authors already realize that and plan a journal publication focusing on that aspect. If not, they should elaborate a bit more on that point.

**Authors** We would like to thank you for your praiseful appreciation of our work. Yes, we are writing a journal article focusing on the compensation of systematic errors in actual residual stress measurements and not only in identifications of applied bending stresses alone. It hasn't been submitted yet, due to an extensive experimental campaign. Hopefully, it will be submitted beginning of next year.

Anyway, we elaborated the 4th point by specifying how we intend to follow up this activity: "Since the bench permits a *simultaneous* identification of residual and bending stresses, the compensations applied for the bending case (to improve correlation with imposed stresses) can be easily extended to residual stresses, as they share most of the factors that may affect the hole-drilling method procedure, such as the hole geometry and eccentricity, the strain gauge setup, and a zero-depth offset. This will increase the accuracy of the residual stress measurement. This strategy will be investigated in a future work, by comparing hole-drilling measurements (before and after compensations) with X-Ray diffraction measurements".

**Reviewer** One small grammar suggestion add “the” twice to make it “The latest release of the ASTM...” in the abstract and text.

**Authors** Thank you! It was our mistake.

<footnote n="1">¹ Department of Civil and Industrial Engineering, University of Pisa, Italy</footnote>

<footnote n="2">² SINT Technology Srl, Florence, Italy</footnote>

<footnote n="3">³ Los Alamos National Laboratory, Los Alamos, New Mexico, USA</footnote>

<footnote n="4">⁴ Physical Metallurgy Metal-forming and Nanotechnology Institute, University of Miskolc, Hungary</footnote>

<footnote>R Reviewer</footnote>

<footnote>E Editor</footnote>
Reviewer 2 (Anonymous)

**Reviewer** This paper describes a calibration bench that may be used to investigate systematic errors that may be induced during hole-drilling residual stress measurements. The work is carefully done and clearly described. The paper has two major themes, (1) the design of the calibration bench, and (2) the use of that bench to investigate the effect in the uncertainty of the zero depth assignment due to hollow drill shape. The title of the paper focuses on the first theme, but I hope that the authors will forgive me in mentioning that although the design of the bench is a significant engineering achievement, the second theme is of more widely useful scientific interest. Certainly, as identified in the manuscript, the reliable identification of the effective zero-depth datum has a major effect, especially near the material surface. Thus, the important message of the paper regarding choice of zero hole depth datum will be of much wider interest to the residual stress measurement community. Thus, the authors could perhaps consider a change in title to focus on the zero depth datum issue and adjust the emphasis of the text to fit. The recommended adjustment of -0.0129 mm that is found to give the best-fit results corresponds quite closely to the adjustment that would be expected by extrapolating the measured strain curves in Fig.8(a) back to the zero strain line, thereby eliminating the “dead” zone near the origin. I recall reading a paper some years ago that suggested such a procedure, but I cannot now remember its author or citation, sorry! Perhaps the present authors may recall this paper, it would be worth citing in the new paper.

**Authors** We truly thank you for your appreciation of our work. We absolutely agree on the practical significance of the two themes described in our work. The bench is actually a tool that will be used to implement the described compensation procedures on real-world residual stress measurements. As a matter of fact, we went to the ICRS conference in order to collect industrial interest on measurements carried out with this bench and pave the way for our future experimental campaign. As you correctly observed, there was a much wider interest in the compensation procedures, than in the identification of bending stress distribution itself.

Concerning the paper that suggested a similar zero-depth correction procedure, we are quite sure that you're recalling a paper from our research group, published on *Strain* in 2011 (Ref. [13] in the manuscript). Therein, we manually shifted the strain curves until the tangent line of the first few points intercepted the axes origin; it worked well, but the choice of how many points had to be included was a bit arbitrary.

In order to underline these aspects of the work, we changed the title from: "A calibration bench to validate systematic error compensation strategies in hole drilling measurements" to: "Revealing systematic errors in hole drilling measurements through a calibration bench: the case of zero-depth data".

We also tailored other parts of the manuscript:

*Abstract*

The imperfect hole geometry and drilling alignment are proven to cause a significant underestimation of stresses near the surface, as they lead to an incorrect identification of the zero-depth datum. It is shown that this effect can be corrected through the proposed calibration bench.

*Section 2.2*

Although a precise modeling of a non-cylindrical hole falls outside the axisymmetric hole model used in the HDM, this effect can be seen as an error in the identification of the "true" zero-depth datum, as observed in [13]. For example, the effect of a 0.02 mm depth shift (compatible with Fig. 7) of the strains is reported in Fig. 9b: the largest effect is precisely near the zero-depth point.

Hence, while keeping matrix A constant and modifying the strains only, $\Delta h$ can be automatically chosen as the one which minimizes the norm of the stress second-order numerical derivative, to enforce smoothness and avoid the abrupt stress deviation near the surface.

*Section 3*

Since the bench permits a *simultaneous* identification of residual and bending stresses, the compensations applied for the bending case (to improve correlation with imposed stresses) can be easily extended to actual residual stresses in the specimen, as they share most of the factors that may affect the hole-drilling method procedure, such as the hole geometry and eccentricity, the
strain gauge setup, and a zero-depth offset. This approach will increase the accuracy of the residual stress measurement and will be investigated in a future work. Various surface treatments will be analyzed, and hole-drilling measurements (before and after compensations) will be compared with X-Ray diffraction measurements, which are not affected by the zero-depth issue.

## Editor's assessment (Lazslo Toth)

This paper was selected by the organizers of the 11th International Conference on Residual Stresses (ICRS11, chair: Prof. Sabine Denis), for submitting it for publication in JTCAM.

There were two referees; the first one (expert in the field), proposed to accept as it was (he said: rarely happened to him to accept as is, but the paper really met all conditions), while the other marked major revision. In reality, his comments were indicating only minor revisions. Nevertheless, the Authors took nearly 6 months for revising the paper.

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