A. Schiavi, A. Prato, F. Mazzoleni, A. Facello, A. Kwitonda
METROLOGICAL CHARACTERIZATION OF DIGITAL MEMS ACCELEROMETERS IN DYNAMIC CONDITIONS: AN INVESTIGATION OF LINEARITY IN AMPLITUDE AND TEMPERATURE EFFECTS

In several applications, such as industrial plants monitoring, or peculiar manufacturing process, the sensors are subjected to a wide range of acceleration amplitude levels or shocks, as well as thermal changes, that could affect the micro electro-mechanical inner parts, altering their performance and reliability. In this work, by applying a calibration procedure developed at INRIM, the main sensitivity of digital MEMS accelerometers is evaluated, as a function of amplitude, in the frequency domain. Moreover, a survey of temperature drift, from -20 °C up to 80 °C, is also performed, to characterize the suitability of digital MEMS accelerometers for actual applications.

N. Yan, L. Klaus, T. Bruns
LOW FREQUENCY PRIMARY VIBRATION CALIBRATION USING A MULTI-COMPONENT SHAKER

The multi-component vibration calibration device at PTB consists of a triaxial shaker which is suitable and convenient for calibrating multi-axial seismometers. Three laser vibrometers are furthermore utilised as references. The frequency range was further extended for a European research project. Instead of a closed-loop control system limiting the vibration frequency down to 0.4 Hz, a signal generator is now used to provide the excitation voltage to the amplifier of the shaker in open-loop mode. This excites the shaker yielding vibrations with significantly lower frequencies. The first test measurements with a seismometer were carried out. The results demonstrate that a calibration down to 10 mHz is easily achievable.

M. B. Tuğcu, C. Kuzu, E. Pelit, A. Dizman
INTERLABORATORY COMPARISON IN ROCKWELL HARDNESS SCALES BETWEEN TÜBİTAK UME AND TSE

An interlaboratory comparison between TÜBİTAK UME (National Metrology Institute of Türkiye) and TSE (Turkish Standards Institution) was organized in the field of Hardness Metrology to determine the consistency of the primary hardness standard machine of TÜBİTAK UME and hardness calibration machine of TSE realizing Rockwell Hardness measurements in accordance with ISO 6508-1:2016 and ISO 6508-3:2015 standards.
In this study the procedure and measurement results of the interlaboratory comparison between the two institutes are explained.

J. D. Fidelus, D. Bejma, A. Prato, A. Germak
ALIGNMENT TILT AND FORCE TRANSDUCER CREEP EFFECTS ON HARDNESS IN CONVENTIONAL HARDNESS TESTS

This paper describes the investigations of alignment effects and the influence of force transducer creep in conventional hardness tests performed on GUM’s deadweight-type Rockwell Hardness Standard Machine (HSM), Vickers Hardness Machine (HM), Brinell HM and INRiM’s Primary Hardness Standard Machine (PHSM).

Pierluigi Rizza, Renato Machado, Alessandro Germak
DETERMINATION AND UNCERTAINTY PROPAGATION OF SENSITIVITY COEFFICIENTS IN ROCKWELL HARDNESS MEASUREMENTS

In the field of hardness measurements, a problem arises when trying to understand how different measurement parameters (speed of the indenter, force, thermal drift, etc.) affect the outcome of the measurement itself. Because the mathematical model defining hardness scales do not consider such factors, the simplest way to include additional influence parameters in the mathematical model is to introduce them linearly via sensitivity coefficients, which are obtained experimentally and thus characterized by uncertainties. Uncertainties of the sensitivity coefficients are in general not considered in the evaluation of the combined standard uncertainty of the hardness measurements. In this paper a general procedure is presented and applied to HRA and HRC measurements.