H. Nozato, W. Kokuyama, A. Oota
A comparison measurement using homodyne and commercial heterodyne laser interferometers was investigated in the primary shock facility of NMIJ. Each derived shock waveform was calculated by applying a two stage differentiation process with 4 th order Butterworth lowpass filter. As results, the time difference and the deviation between peak accelerations for two amplitude levels were respectively less than 1 µs and quite less than 0.01 %.
TC22 Conference 2014
· TC22
· 2014
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Naveen Garg, Tushya K. Saxena, Mark I. Schiefer
The paper presents a bilateral comparison for measurement of accelerometer sensitivity in frequency range from 0.1 Hz to 20 kHz between NPL, India and The Modal Shop, USA. Two artefacts were utilized for bilateral comparison, one PCB 353B04 sensor and another for the low frequency, PCB Q353B51 along with ICP sensor signal conditioner. The measurements were conducted in the low frequency range from 0.1 Hz to 100 Hz for the PCB Q353B51, while the PCB 353B04 sensor was used in frequency range 5 Hz to 20 kHz. The results of the bilateral comparison show an E n value less than 0.5 for both the...
TC22 Conference 2014
· TC22
· 2014
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C. Hirunyapruk, V. Plangsangmas
Vibration exciters can cause several problems of vibration calibration. The classical one comes from the exciter resonances, which are closed to some calibration frequencies. Although efforts have been made in the design stage to overcome the resonance problems, some of them still exist in particular calibration conditions. In this paper, the resonances of a Brüel & Kjær vibration exciter system (model 4805 with 4811) are studied theoretically and experimentally. A mass-spring model is used to describe the vibration characteristics of the exciter system. The measured resonances are extracted...
TC22 Conference 2014
· TC22
· 2014
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Thomas Bruns, Frank Blume, Henrik Volkers
The application of heterodyne interferometry with direct access to the frequency modulated signal was deemed unfeasible for low frequency vibration measurement, because of the trade-off between a carrier frequency and modulation bandwidth in the MHz range calling for high sampling rates on the one hand, and the low vibration frequency calling for long measuring times on the other hand. Data acquisition systems with the necessary amount of sample memory are expensive and the CPU time needed for the appropriate data processing becomes prohibitive at very low vibration frequencies. PTB recently...
TC22 Conference 2014
· TC22
· 2014
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Benjawon Thummawut, Chompoonoot Hirunyapruk, Virat Plangsangmas, Paramate Horkaew
This paper presents the design and implementation progress of the vibration calibration system by using the Sine Approximation Method at the National Institute of Metrology Thailand (NIMT). This system was set up in accordance with ISO16063-11, The Sine Approximation. The experiments were conducted on a prototype design and constructed at our calibration laboratory. The obtained results were subsequently validated against existing systems. More specifically, the magnitude and phase sensitivity and related statistics were validated with the SPEKTRA Calibration System. In this paper, the...
TC22 Conference 2014
· TC22
· 2014
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A. Schiavi, A. Germak, F. Mazzoleni, D. Riva
The study of posture and movement control in humans requires technological supports able to provide accurate, reproducible and repeatable information on displacement and/or position in real-time. A methodology used in rehabilitation and in sports medicine involves the use of rocking boards on which the subjects must keep their balance, in different operating conditions. The use of rocking boards combined with displacement and position sensors allocated at specific points of the human body, can provide information on the single stance stability and contribute to reprogramming the postural and...
TC22 Conference 2014
· TC22
· 2014
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C. S. Veldman
The National Metrology Institute of South Africa (NMISA) has implemented a system to measure the transverse sensitivity of vibration transducers. As a mechanical device, the principle sensing axis of an accelerometer is not 100 % perpendicular to the mounting axis. This gives rise to the effect that the accelerometer will produce an electrical output even when a mechanical input perpendicular to the principle measurement axis is applied. The quantification of this “defect” parameter is of importance when high accuracy acceleration measurements are performed using accelerometers. This paper...
TC22 Conference 2014
· TC22
· 2014
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T. Aleksandrov Fabijanić, M. Franz, Ž. Alar
Hardness uniformity is the most important property of hardness block and depends on the quality of the starting material, process of obtaining, heat and surface treatment. All parameters must be selected very carefully to achieve homogenous microstructure with no defects. Vickers hardness blocks for the high hardness range were produced by two different processes of powder metallurgy; conventional liquid phase sintering in hydrogen and sinter HIP. Nano powder of WC with a grain size of 150 nm with specific surface area of 2,5 m²/g and addition of grain grow inhibitors was used as staring...
TC5 Conference 2014
· TC5
· 2014
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Tassanai Sanponpute, Nitiwat Sasom, S. S. K. Titus
National institute of metrology (Thailand), NIMT studied behavior of hardness change on 25 and 40 HRBW. There is not only number of indentations but also other several influences cause to stability of hardness measurement. Some dominance factor such as diameter size of anvil, block thickness and indenting pattern were taken into account for scope of experiments. Set of 25 and 40 HRBW reference hardness block were provided, consisting of 6, 8.5, 10.5 and 11 mm thickness. Hardness tested on one with various anvil sizes, 6, 12 and 60 mm diameter. The tests proceeded on different indenting...
TC5 Conference 2014
· TC5
· 2014
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Dieter Schwenk
Each recording of measurement values postulates the consistency of the realization and mapping of the measurement scale by the measuring device. The transfer of a measurement scale to a measuring or testing device at two or more data points is done in a linear space. A functional relationship between measurement scale and measured value realization is derived from regression analysis. A differentiation can be made between systematic, random and symmetric deviations between measurement realization and measurement scale. The systematic and symmetric deviations are compensated by using a...
TC5 Conference 2014
· TC5
· 2014
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