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Gary S Schajer - One of the best experts on this subject based on the ideXlab platform.

  • Compact Calibration Data for Hole-Drilling Residual Stress Measurements in Finite-Thickness Specimens
    Experimental Mechanics, 2020
    Co-Authors: Gary S Schajer
    Abstract:

    The conventional way to present Integral Method calibration data for Hole-Drilling residual stress measurements is in the form of a large triangular table of numbers. In the common case where 20 Drilling steps are used for the Hole-Drilling measurement, 231 numerical coefficients are needed. While such tables are effective, their bulk inhibits their use for other than the most common experimental arrangements; the convenience and usefulness of the Hole-Drilling method would be much extended if the bulk of the calibration data could be reduced. Here, a two-variable polynomial formulation is proposed to represent the Hole-Drilling calibration data. It comprises 15 numerical coefficients and provides calibration data with average accuracy within 1%, with occasional outliers reaching around 2%. The compactness of the calibration stimulated exploration of Hole-Drilling response beyond the conventional “thick” specimen case, also to include finite thickness specimens down to very thin (through-Hole) geometries. Tables of calibration data are provided here for ASTM E837 Type A, B and C strain gauge rosettes, for various Hole diameters, for conventional “thick” specimens, and for finite thickness specimens down to the through-Hole case.

  • Hole-Drilling Method for Measuring Residual Stresses
    2018
    Co-Authors: Gary S Schajer, Philip S. Whitehead
    Abstract:

    Abstract This book describes the theory and practice of the Hole-Drilling Method for measuring residual stresses in engineering components. Such measurements are important because residual stresses have a "hidden" character because they exist locked-in within a material, independent of any external load. These stresses are typically created during component manufacture, for example, during welding, casting, or forming. Because of their hidden nature, residual stresses are difficult to measure and consequently are often ignored. However, they directly add to loading stresses and can cause catastrophic failure if not properly included during engineering design. Thus, there is an urgent need to be able to identify and measure residual stresses conveniently and reliably. The Hole-Drilling Method provides an adaptable and well-proven method for measuring residual stresses in a wide range of materials and component types. It is convenient to use and gives reliable results. Because of the hidden nature of residu...

  • Measurement of Structural Stresses by Hole-Drilling and DIC
    Experimental Mechanics, 2016
    Co-Authors: Joshua Harrington, Gary S Schajer
    Abstract:

    Evaluation of stresses in structures such as bridges, buildings, pipelines and railways is challenging because the loads cannot easily be manipulated to allow direct measurements. This paper focuses on the development of a method that combines the Hole-Drilling technique with Digital Image Correlation (DIC) to evaluate these difficult-to-measure structural stresses. The Hole-Drilling technique works by relating local displacements caused by the removal of a small amount of stressed material to the original stresses within the drilled Hole. Adaptation of this method to measure structural stresses requires scaling up the Hole size and modifying the calculation approach to measure deeper into a material. DIC provides a robust means to measure full-field displacements that can easily be scaled to different Hole sizes and corrected for typical artifacts that occur in practical on-site measurements. There are two primary areas of investigation: the adaptation of the DIC/Hole-Drilling method to measure structural stresses and the development of a correction method to remove coexisting stresses such as residual and machining stresses from the measurement. Experimental measurements are made to demonstrate the measurement method on different structure types including the example practical problem of measuring thermally induced stresses in railroad tracks.

  • Residual Stress Measurements in Finite-Thickness Materials by Hole-Drilling
    Experimental Mechanics, 2014
    Co-Authors: Gary S Schajer, C. Abraham
    Abstract:

    Hole-Drilling measurements of residual stresses are traditionally made on materials that are either very thick or very thin compared with the Hole diameter. The calibration constants needed to evaluate the local residual stresses from the measured strain data are well established for these two extreme cases. However, the calibration constants for a material with finite thickness between the extremes cannot be determined by simple interpolations because of the occurrence of local bending effects not present at either extreme. An analytical model is presented of the bending around a drilled Hole in a finite thickness material and a practical procedure is proposed to evaluate the corresponding Hole-Drilling calibration constants.

  • residual stress measurement in veneering ceramic by Hole Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Abstract Objectives Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5–1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics.

M. J. Sadoun - One of the best experts on this subject based on the ideXlab platform.

  • residual stress measurement in veneering ceramic by Hole Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Abstract Objectives Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5–1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics.

  • Residual stress measurement in veneering ceramic by Hole-Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Objectives: Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods: The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results: All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance: The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. © 2010 Academy of Dental Materials.

Amélie K. Mainjot - One of the best experts on this subject based on the ideXlab platform.

  • residual stress measurement in veneering ceramic by Hole Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Abstract Objectives Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5–1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics.

  • Residual stress measurement in veneering ceramic by Hole-Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Objectives: Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods: The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results: All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance: The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. © 2010 Academy of Dental Materials.

Alain J. Vanheusden - One of the best experts on this subject based on the ideXlab platform.

  • residual stress measurement in veneering ceramic by Hole Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Abstract Objectives Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5–1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics.

  • Residual stress measurement in veneering ceramic by Hole-Drilling
    Dental Materials, 2011
    Co-Authors: Amélie K. Mainjot, Alain J. Vanheusden, Gary S Schajer, M. J. Sadoun
    Abstract:

    Objectives: Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. Methods: The Hole-Drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. Results: All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0 mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. Significance: The Hole Drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. © 2010 Academy of Dental Materials.

D V Nelson - One of the best experts on this subject based on the ideXlab platform.

  • Residual stress determination by Hole Drilling combined with optical methods
    Experimental Mechanics, 2010
    Co-Authors: D V Nelson
    Abstract:

    Abstract An overview is provided of the use of eight different optical methods with Hole Drilling to determine residual stresses. The\nmethods considered are: brittle and photoelastic coatings, Moire interferometry, holographic interferometry, electronic speckle\npattern interferometry, interferometric strain rosette, digital image correlation and shearography. A number of applications\nare summarized, such as the use of Hole Drilling with holographic interferometry to investigate stresses in rock structures\naccessed by deep boreHoles and to determine manufacturing-induced residual stresses in fillets of small radii.

  • Residual stress determination using Hole Drilling and 3D image correlation
    Experimental Mechanics, 2006
    Co-Authors: D V Nelson, Akihiro Makino, T Schmidt
    Abstract:

    In recent years, the Hole Drilling method for determining residual stresses has been implemented with optical methods such as holographic interferometry and ESPI to overcome certain limitations of the strain rosette version of Hole Drilling. Although offering advantages, the interferometric methods require vibration isolation, a significant drawback to their use outside of the laboratory. In this study, a 3D image correlation approach was used to measure micron-sized surface displacements caused by the localized stress relief associated with Hole Drilling. Residual stresses were then found from the displacements using non-dimensional relations previously derived by finite element analysis. A major advantage of image correlation is that it does not require interferometric vibration isolation. Experiments were performed to check the ability of this new approach for uniaxial and equi-biaxial states of stress. Stresses determined by the approach were in good agreement with computed values and those determined by Hole Drilling using holographic interferometry.

  • Determination of Biaxial Residual Stresses by a Holographic-Hole Drilling Technique
    Journal of Engineering Materials and Technology-transactions of The Asme, 1996
    Co-Authors: Akihiro Makino, D V Nelson, Elizabeth A. Fuchs, D. R. Williams
    Abstract:

    A technique is described for the rapid determination of residual stresses through the combined use of Hole Drilling and holographic interferometry. A small diameter blind Hole is drilled into a part containing residual stresses and the displacement field caused by localized stress relief is registered using holographic interferometry instead of a strain gage rosette. The optical interference fringe pattern created in the hologram upon release of stress is analyzed by a fringe counting method that allows stresses to be computed quickly. A comparison of stresses determined by the holographic Hole Drilling technique with different known biaxial residual stresses is shown.

  • On the use of the Hole-Drilling technique for residual stress measurements in thin plates
    Journal of Pressure Vessel Technology-transactions of The Asme, 1992
    Co-Authors: Roy W. Hampton, D V Nelson
    Abstract:

    The strain gage blind Hole-Drilling technique may be used to determine residual stresses at and below the surface of components. In this paper, the Hole-Drilling analysis methodology for thick plates is reviewed, and experimental data are used to evaluate the methodology and to assess its applicability to thin plates. Data on the effects of gage pattern, surface preparation, Hole spacing, Hole eccentricity, and stress level are also presented.