IMEKO Event Proceedings Search

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Jacob Holm Winther, Martin Brucke, Martin Thalbitzer Andersen, Torben Rask Licht
RECENT STUDY IN PRIMARY ACCELEROMETER CALIBRATION - PROGRESS, DEVELOPMENT AND LESSONS LEARNED

Primary calibration of accelerometers by laser interferometry has been performed for more than 50 years. It was made possible by the advent of the commercial He-Ne lasers in the 1960ties. During the last 20 years the progress in digital signal treatment has made it available for most interested laboratories.
However, these huge progresses have merely reduced but not removed some basic problems.
- The quality and basic parameters of the exciter systems
- The influence from the mechanical setup on the accelerometer and thereby on the measurement results.
This paper describes several topics and considerations found relevant for primary calibration of accelerometers, following recent international intercomparisons and progress in the calibration grade vibration exciter system design.

J. Berry, P. Lovelock, I. A. Robinson, J. Urquhart
VIBRATIONAL ANALYSIS FOR THE NEXT GENERATION NPL KIBBLE BALANCE

Low uncertainty Kibble balance measurements require careful consideration of the effect of external sources of vibration. This paper compares vibrational modelling of the machine frame of the National Physical Laboratory’s next generation Kibble balance using three different software packages. The output of the modelling on the machine frame showed that the first modes of vibration were all above the design requirement of 60 Hz.
The model was then enhanced to include the moving section of the balance modelled with two types of guidance mechanism. The output from the modelling showed a reduction in the resilience of the balance to lateral vibrations but the linkage type guidance mechanism was still resilient to induced vibrations at frequencies up to 50 Hz.

Henrik Volkers, Benedikt Seeger
USING COMMONLY AVAILABLE NETWORK EQUIPMENT FOR LASER DOPPLER VIBROMETER EXCITATION AND CALIBRATION

We have demonstrated that commonly available small form-factor pluggable (SFP) modules can be used for LDV excitation and calibration. While the expected intensity modulation at the photodiode inside the LDV interferometer is sinusoidal, the SFP module output is designed for and provides a rectangular modulation shape. The conducted experiments produced comparable results.

B. Seeger, Th. Bruns
ABSOLUTE TIME-BASED DYNAMIC MULTI-SENSOR CALIBRATION FOR MEMS ACCELEROMETERS – A CONCEPT STUDY

This paper describes an absolute time-based concept to simultaneously calibrate a large number of MEMS sensors using Ethernet as communication interface and investigates new uncertainty influences related to the absolute time base.

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.

C. S. Veldman
SELF-MADE TRI-AXIAL ACCELEROMETER DESIGN CONSIDERATIONS FOR VALIDATION OF SIMULTANEOUS MULTI AXIS ACCELEROMETER CALIBRATION SYSTEM

This paper describes geometric design consideration for the creation (manufacture) of a tri-axial accelerometer intended for the validation of multi axis calibration systems that implements simultaneous axis calibration methods. Two mounting geometries were investigated, and the results obtained using them are reported. The one configuration, a cube with counterweights. The second configuration see the accelerometers mounted on “recessed” faces, aiming at placing (aligning) the individual accelerometers close to the vibration excitation vector.

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.

C. Kuzu, E. Pelit, İ. Meral
DESIGN AND DEVELOPMENT OF HARDNESS INDENTATION MEASUREMENT SYSTEM AT TÜBİTAK UME

Developments in reference standards in Hardness Laboratory of TÜBİTAK UME (National Metrology Institute of Türkiye) and the demand received from calibration and testing laboratories forced us to develop a new hardness indentation measurement system (HIMS) that covers all Brinell, Vickers and Knoop hardness indentation measurements. In this design it has been aimed at automatization of measurements, constitution of different methods for determination of border of indentation and in turn measurement of the size (diameter and diagonal length) of indentations. In this paper design, installation and metrological characterization of HIMS developed by TÜBİTAK UME Hardness Laboratory is explained in detail.

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.

Sun Qinmi, Li Haibin, Li Xuefei, Cheng Yuanyuan
DESIGN OF A NEW TYPE OF BUCHHOLZ HARDNESS TESTER

This paper describes a new type of Buchholz Indentation Hardness Tester used in Buchholz Indentation test for paint and varnishes. This new type tester uses a bridge structure to connect two cantilever sensors together, so we can instantly know the magnitude of the acting load on paint and varnishes. The design overcomes the defects of the previous load changes that could not be accurately predicted. At the same time we can use the adjustment hole to accurately adjust the level of the hardness tester, to ensure the standardization of the measurement process. By evaluating the uncertainty of the measurement results, the newly designed hardness tester ensures the accuracy and reliability of measurement results.

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