NCAL: International Documentary Standards Activities

Summary

As the National Measurement Institute (NMI) for the United States of America, a primary focus of NIST is the development of documentary standards for measurement and test methods.  NCAL has a long history of participation in international documentary standards through ASTM International and the International Standards Organization (ISO).  Our focus has been on mechanical testing methods for metals and composites, and the measurements made before, during, and after those tests.  In recent years, we have focused on the use of the digital image correlation (DIC) technique due to its expanded use by industry.

Description

NIST Center for Automotive Lightweighting (NCAL) staff participate in many different international standards committees (e.g. ISO TC 164, ASTM E28 and D30); however, our main focus has been in the mechanical testing of metals and, to a lesser extent, composites.  We work on the calibration and verification of testing and measurement equipment (e.g. alignment, force, displacement, extensometry, temperature, X-ray diffraction) and its use in various test methods (e.g. quasi-static and high-strain rate, uniaxial, biaxial, elastic properties, plastic properties, forming limits).  

Standards Organizations Leadership

NCAL works with our industrial stakeholders to identify standards needing revision and new standards needing development.  This participation includes both leadership roles (e.g. Head of Delegation, Subcommittee Chair, Task Group Chair, Project Leader) and as regular participants in standards development organizations and prestandards work for emerging technologies.  Our staff works within standards and prestandards bodies to build consensus between the various interested parties (i.e. end users, equipment producers, commercial and industrial testing laboratories) and to define a common terminology for mutual understanding.  Through measurement uncertainty analyses and interlaboratory studies we keep an eye on repeatability, reproducibility, and traceability of the measurements.  We share our knowledge and experience through the standards development process, good practices development, workshops, technical meetings, symposia, consortia, and more directly with stakeholders through cooperative research and development agreements (CRADA) and one-on-one interactions.

Digital Image Correlation

One example of an emerging technology, on which NCAL has focused, is digital image correlation (DIC), that in the last 25 years has gone from an academic research topic to a commercial measurement technique used in industrial research and development laboratories worldwide.  Unfortunately, the standards bodies have not kept up with the rapid expansion of this technology.  To address this shortcoming, NCAL staff have worked with standards bodies to incorporate the ad hoc use of DIC in some forming standards (e.g. forming limit standards in ASTM and ISO), to better define the use of DIC as a non-contacting extensometer, and helped start the International Digital Image Correlation Society (iDICs).  iDICs is composed of members from academia, government, and industry, and its mission is to train and educate users of DIC systems and to standardize DIC practice.  NCAL has worked through iDICs to develop the iDICs Good Practices Guide for DIC, which is recognized internationally as the closest thing to a standard for DIC measurements and is used as a training manual for practitioners looking to be certified in DIC measurements.  The guide also describes reporting requirements to aid both the proper publication of DIC results and to help our industrial stakeholders to specify and contract DIC measurements.  NCAL also had a leadership role in the iDICs DIC Challenge which produces benchmark data used for DIC code testing, validation, and improvement.

Major Accomplishments

• Revisions to forming limit standards (ASTM E2218, ISO 12004-1 and 12004-2)
• Other standards, fiber optic strain gauges (ASTM E3410), miniature tensile test (ASTM E8/E8M Annex), r-value (ASTM E517, ISO 10113)
• E. M. C. Jones and M. A. Iadicola, eds., “A Good Practices Guide for Digital Image Correlation” (International Digital Image Correlation Society, October 2018). https://doi.org/10.32720/idics/gpg.ed1.
• A. Creuziger and M. D. Vaudin, “Data Publication: Data from NIST IR ‘Report on VAMAS Round Robin of ISO 13067: Microbeam Analysis - Electron Backscatter Diffraction - Measurement of Average Grain Size,’” September 21, 2023, https://doi.org/10.18434/mds2-2951.
• P. L. Reu et al., “DIC Challenge 2.0: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses,” EXPERIMENTAL MECHANICS 62, no. 4 (April 2022): 639–54, https://doi.org/10.1007/s11340-021-00806-6.
• Matthias Merzkirch and Tim Foecke, “10° Off-Axis Testing of CFRP Using DIC: A Study on Strength, Strain and Modulus,” COMPOSITES PART B-ENGINEERING 196 (September 1, 2020), https://doi.org/10.1016/j.compositesb.2020.108062.
• P. L. Reu et al., “DIC Challenge: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses,” EXPERIMENTAL MECHANICS 58, no. 7, SI (September 2018): 1067–99, https://doi.org/10.1007/s11340-017-0349-0.
• A. Creuziger and M. D. Vaudin, “Report on VAMAS Round Robin of  ISO 13067: Microbeam Analysis – Electron Backscatter Diffraction – Measurement of Average Grain Size,” NIST Internal Report, NIST IR, September 2011, https://doi.org/10.6028/NIST.IR.7814.
• T. Foecke and T. Gnaeupel-Herold, “Robustness of the Sheet Metal Springback Cup Test,” METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE 37A, no. 12 (December 2006): 3503–10, https://doi.org/10.1007/s11661-006-1045-3.
• T Gnaeupel-Herold et al., “An Investigation of Springback Stresses in AISI-1010 Deep Drawn Cups,” MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 399, no. 1–2 (June 15, 2005): 26–32, https://doi.org/10.1016/j.msea.2005.02.017.
• T Gnaeupel-Herold et al., “A Synchrotron Study of Residual Stresses in a Al6022 Deep Drawn Cup,” MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 366, no. 1 (February 5, 2004): 104–13, https://doi.org/10.1016/j.msea.2003.08.059.