Evaluation of Measurement Uncertainty for the Absorbed Energy of Pendulum Impact Testing Machines: a Comparative Analysis of Methods and Metrological Examination of GOST 9454–2025

The revision of standards for methods of determining the mechanical properties of metals has revealed an urgent need for the standardization of approaches to uncertainty evaluation that ensure metrological traceability to state primary standards.

The aim of this work is to systematize the methods for evaluating the measurement uncertainty of аbsorbed energy and to identify the dominant factors affecting accuracy.

Based on the classical concept described in GOST 34100.3–2017 (ISO/IEC Guide 98-3:2008) “Uncertainty of measurement. Part 3. Guide to the expression of uncertainty in measurement”, a mathematical and practical comparative analysis of three approaches was carried out.

It has been established that the method for impact testing machines compliant with GOST 10708–82 “Pendulum impact testing machines” is the simplest; the calibration method according to ISO 148-2:2016 “Metallic materials — Charpy pendulum impact test — Part 2: Verification of testing machines” is the most accurate. It is shown that the use of certified reference materials, unlike other methods, ensures traceability to a reference value and automatically accounts for contributions from striking edge and support wear. During the study, metrological contradictions were identified in the new version of GOST 9454–2025 “Metals. Method fortesting the impact strength at low, room and high temperature”: it has been proven that the algorithms proposed exclude friction loss and the initial potential energy of the pendulum, which leads to a dangerous underestimation of the uncertainty evaluation.

The calculated uncertainty budgets showed that, in practice, the dominant sources are scale resolution and misalignment of the centers of percussion. The obtained algorithms are planned to be included in the draft national standard for the verification of pendulum impact testing machines and to be used in the development of new certified reference materials.

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