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Page 825 of 936 Results 8241 - 8250 of 9356

Toshiyuki Hayashi, Yoshihisa Katase, Kazunaga Ueda,Tsuyoshi Hoshino, Hiroshi Suzawa, Masaaki Kobayashi
Performance of force comparator with reference to tuning-fork type force transducer

A force comparator was constructed using a conventional screw-driving type uniaxial testing machine. A tuning-fork type force transducer was used as the reference. A strain-gauge type force transducer was calibrated with the comparator using springs and bearings to relax eccentric forces and moments. In comparison with a conventional dead-weight type force standard machine, deviation of up to only 1 mN at the rated capacity of 50 N was observed. There were still some limitations in terms of force controlability and obstructive eccentric forces; nevertheless, the force comparator exhibited favorable performance for the calibration of commercial force transducers. The tuning-fork type force transducer was suitable as the reference because of its long-term sensitivity stability and small hysteresis.

Aimo Pusa
The long-term behaviour of force transducers as a criteria for the selection of new transfer standards

The laboratory of MIKES-Lahti Precision Oy has made over almost twenty years comparisons with the PTB, utilizing more than ten different force transducers. These comparisons have been made regularly every year to supervise the traceability of force. The results of these comparisons are showing different kinds of behaviours. For the traceability the most important characteristic is the stability of the sensitivity. The change of the sensitivity directly influences the measurement uncertainty and as a result affects the final uncertainty of the intercomparison. The second characteristic is the zero reading, which can indicate the change of the measurement behaviour of the transducer.

Oliver Mack
Add-on of the 2-MN force standard machine for testing load cells

This paper presents a new temperature chamber in combination with the 2-MNdeadweight force standard machine (FSM) which allows testing and certification of load cells with nominal loads up to 2 MN (200 t) by the Physikalisch-Technische Bundesanstalt (PTB). This facility is unique in Europe; for the first time it offers manufacturers and customers the possibility to certify load cells with very high nominal loads as used in the heavy industry for instance.
In spite of a small installation space for the temperature chamber which is limited by the construction of the FSM the temperature chamber permits measurements in a temperature range from -20°C to +55°C combined with small spatial and temporal temperature gradients of < 0.2 K per 100 mm and per hour. Thus it fulfils entirely the requirements for testing load cells as defined in the OIML-Recommendation R60.

Kamlesh K. Jain, S.S.K. Titus, H.N.P. Poddar and S.K. Dhulkhed
Realization of forces (2N-20N) by primary method

The present paper describes the preliminary results of the metrological characterization of the newly design and developed force machine to realize the forces in the range 2N- 20N with an expanded uncertainty of 50 ppm. The characterization of the machine is carried out in compression using two transfer force standards of 5 and 20 Newton capacity. The calibration of the transfer standards directly against the dead weight force machine shows that the repeatability and reproducibility are better than 0.002% and 0.003% respectively, over the full range of measurement.

Mark I. Schiefer
New Techniques in Primary Accelerometer Calibration

This paper will discuss a newly developed implementation of ISO 16063 style primary accelerometer calibrations. The goal is a laser primary accelerometer calibration system capable of performing low uncertainty primary accelerometer calibrations while maintaining the throughput and simplicity of a traditional back-to-back calibration system.
Primary accelerometer calibrations typically require multiple measurement passes at several locations across the device to be calibrated by primary means. This paper discloses the novel use of a dual beam, simultaneous primary calibration laser interferometer based system. The use of dual beam and multiple pass Michelson Interferometers greatly improves not only the reliability of the measurement, but significantly simplifies the setup and measurement process of primary laser calibrations of accelerometers.

S. Rusnáková, P. Koštial, D. Bakošová, J. Kucerova, M. Mokryšová
Experimental Study of Plates by ESPI

Fibre-reinforced components of various shapes and different boundary conditions (free, clamped, and hinged) commonly occur in practice. Designers need to be able to predict the stiffness parameters and damping values of such components for conditions such as aeroelasticity, acoustic fatigue, and so on. Electronic speckle pattern interferometry (ESPI) can be useful tool for easily determination of Poisson’s ratio, Young's modulus E and shear modulus G from the measured resonant frequencies. In this study we investigate the vibration behaviour of square composite plates with different stacking sequences by ESPI and influence of various thicknesses to resonant frequencies of corresponding mode shapes. Both resonant frequencies and corresponding mode shapes can be compared by numerical calculations by the finite element method. Good agreement is obtained for both results of resonant frequencies and mode shapes. The mode shapes of laminate composite plates are influenced by material properties, boundary conditions, geometry, and the lamination arrangement.

P. RATTANANGKUL, B. THUMMAWUT, V. PLANGSANGMAS,A. OHTA, T. USUDA
The Bilateral Comparison for Charge Sensitivity of Standard Accelerometer between NIMT and NMIJ

The Bilateral Comparison between National Institute of Metrology (Thailand), NIMT and National Metrology Institute of Japan, (NMIJ) was conducted in order to confirm the capability of NIMT. The calibration of charge sensitivity of the accelerometer was carried by interferometry method according to ISO 16063-11. The calibration results were then compared at the frequency range of 50Hz to 5000Hz. The reference standard accelerometer Bruel & Kjaer 8305 was assigned as the artifact.
The calibration methods of NMIJ were according to the Fringe-Counting Method at the frequency range of 20 Hz – 80 Hz and Sine Approximation Method at the frequency range of 100 Hz – 5000 Hz. While the calibration methods of NIMT were according to the Fringe-Counting Method at the frequency range of 50 Hz – 800 Hz and Minimum Point Method at the frequency range of 1000 Hz - 5000 Hz.
The comparison results were agreeable which the EN value was less than 1.0 for the entire frequency range.

Gustavo P. Ripper, Guillermo Silva-Pineda
A bilateral acceleration comparison between CENAM and INMETRO

A bilateral key comparison was conducted in the area of vibration between the National Institute of Metrology, Standardization and Industrial Quality (INMETRO), Brazil and the Centro Nacional de Metrología (CENAM), in Mexico; with INMETRO acting as pilot laboratory. This comparison was registered in the BIPM key comparison database (Mutual Recognition Arrangement - Appendix B) as SIM.AUV.V-K1.1 and the measurements were carried out by the participating laboratories from October 2004 to March 2006. The aim of this exercise was to compare primary interferometric measurements of complex charge sensitivity of standard accelerometers under sinusoidal linear accelerations in the frequency range from 10 Hz to 10 kHz. In addition, it was intended to provide a link between INMETRO and the key comparison reference values (KCRVs) established in the CIPM key comparison CCAUV.V-K1. This link of the regional metrology organization (RMO) key-comparison SIM.AUV.V-K1.1 to the International Committee for Weights and Measures (CIPM) key-comparison CCAUV.VK1 can be established because CENAM participated in both comparisons. Both participants used automated calibration systems based on homodyne quadrature laser interferometers to measure the sensitivity magnitude and the phase shift of two backto- back standard accelerometers in compliance with the international standard ISO 16063-11:1999.
The results reported by the participating laboratories at 30 specified frequencies and the respective calculated degrees of equivalence are presented. These results show an agreement better than 0,3 % from 10 Hz to 5 kHz and than 1% from 6 kHz to 10 kHz in sensitivity magnitude and better than 0,6D in phase shift in the entire frequency range.

Th. Bruns, C. S.Veldman
A Web-based Data Generator for Software-Validation and Algorithm Comparison in Primary Accelerometer Calibration

During the 18th IMEKO World Congress 2006 in Rio de Janeiro the members of the TC22 discussed the options to validate and compare different algorithms used worldwide by NMIs in the field of primary accelerometer calibration. The goal would be to validate calibration results calculated with the help of reference data sets and compare the different algorithms with data sets including well defined disturbances. This would expose the susceptibility or immunity of the algorithms with respect to signal disturbances.
The challenge in such an approach is the multitude of measurement set-ups available in the NMIs and the respective diversity of parameters and data sources. In order to cope with this diversity the approach of a web-based data generator will be introduced. The aim is to provide a browser-based interface for a data synthesis software.
Details about the incorporated calibration set-ups, the considered disturbances, the mode of calculation and the internet technology used for deployment will be discussed in the presentation.

P. Koštial, D. Bakošová, N. Krecmer, M. Mokryšová, S. Rusnáková, J. Kucerová
Experimental Modal Analysis of Tyres by ESPI

With help of the ESPI tool we have determined vibration modes of different tyres. In the paper we studied also the influence of the tyre inflation on the vibration mode dynamic. The obtained results were qualitatively compared with those obtained by application of the finite element method (FEM) in the Marc software environment.

Page 825 of 936 Results 8241 - 8250 of 9356