Investigations on SI-Traceable Dynamic Calibration of Instrumented Charpy Strikers

In this Technical Note, we report on investigations toward an SI-traceable dynamic calibration of instrumented Charpy strikers, performed at NIST from January to December 2017. Although Charpy tests are few-millisecond-duration events in which dynamic phenomena are often clearly present, the force measurements from instrumented Charpy tests are predominantly obtained using static calibrations, which has long been recognized as a source of significant potential errors. We discuss a number of approaches to dynamic calibration, including methods that have previously been implemented at NIST (and elsewhere), and methods that are new in the sense that they are not presently commonly used or incorporated into standards. We describe exploratory tests of some of the new calibration approaches, the results of these tests, and how the information obtained is being applied to further work. A key objective of these investigations is that the calibration be traceable to the International System of Units.