A Proposed Estimation of the Expanded Uncertainty of Charpy Impact Testers

Abstract

Uncertainty estimation is one of the very delicate tasks in the field of measurements. For the purpose of calibration of Charpy impact testing machines, it is necessary to evaluate and identify the expanded uncertainty. Factors affecting the uncertainty estimations are; the uncertainty of reference force and length measuring devices and its long-term instability (drift), machine resolution, rated energy error, indicated energy error, losses due to the drag of the pointer, friction losses in the bearing and air resistance, and other geometric parameters. In this study, the uncertainty estimation of the Charpy impact machines is based on the direct verification used in the BS DIN ISO 148-2 standard.