9762 papers found
Shock calibration is a major concern for a variety of mechanical applications. Examples of affected measurands are acceleration, force or torque. However, only for acceleration a written standard is available. This text discusses the problems which need to be addressed in order to disseminate the respective units for shock applications or to improve the current standard for acceleration and proposes a promising approach to solve them.
We present the current situations and activities related to vibration metrology in Japan. It includes national metrology standard, traceability system, laboratory accreditation scheme, legal metrology regulated by measurement low, and earthquake measurements in Japan.
LNE has taken over the function of accelerometry reference laboratory following the decision of the CEACESTA to give up this activity. This article presents the principal stages in the transfer of the reference for medium and high frequency vibrations.
This paper introduces a new "angle-prism"-based laser interferometer designed for high-precision measurement of angular vibration. The angle prism, fixed on the centre of the rotating axis, is shown to converter its angular motion into the path difference between two parallel laser beams. Their path difference provides a new way of measuring the angular displacement. This angular displacement measurement method is obviously shown to present a new primary method for the calibration of angular vibration pickups. In comparison to the traditional primary calibration methods in ISO/DIS 16063-15,...
Primary angular acceleration calibration standard is developed by CIMM to generate standard rotational angle, angular velocity and angular acceleration, which are traceable to the International System of Units (SI). It can be used to calibrate angular transducers, i.e. angular accelerometer, angular velocity transducer, and rotational angle transducer to obtain amplitude sensitivity and phase shift by sinusoidal vibration. This paper will introduce the mechanic system, control system and measurement system of the standard. Calibration results of angular transducer using the standard also...
The main purpose of this paper is to discuss the problems that are imposed to primary accelerometer calibration due to the use of imperfect vibration exciters. A review of the main problems is presented. Solutions are discussed and some calibration results are presented.
All users of primary calibration systems - excepting the national metrological institutes - are under obligation to trace back their reference standards – their laser vibrometer standards – to their respective national standard if they intend to apply for (or maintain) accreditation or to strive for a very low measuring uncertainty for other reasons. A calibration method will be described in this paper that has been used by the accredited laboratory of SPEKTRA for calibrating a greater number of laser vibrometer standards. All these calibrations proved the reliability and the very low...
Laser interferometry has been used for accelerometer calibration since the late sixties using counters for fringe counting and determination of zeroes at higher frequencies. As the digital techniques evolved during the eighties and nineties it became possible to make more sophisticated treatment of the complex output signals from the interferometer detectors. This was described in the revision of the previous standard ISO 5347-1 resulting in the new ISO 16063-11 in 1999. In this the so-called sine approximation method was introduced. As the input is known to be a sine, a least square fitting...
The International Organization for Standardization (ISO) has developed a set of standards for the calibration of vibration and shock transducers. These standards cover the various aspects of the calibration of vibration and shock transducers and at different accuracy levels. This paper presents the author’s overview of the standards. He investigates and reports on the implementation and application of these standards in an accredited laboratory setup.
We report about a novel optical method based on laser Doppler techniques for shape and vibration monitoring of fast rotating objects. Tip clearance and vibration measurements on a transonic centrifugal compressor preformed during operation at up to 50,000 rpm and 586 m/s blade tip velocity are presented. The results are in excellent agreement with those of capacitive probes and the achieved accuracy was about 20 µm.