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Realization of Acceleration

Working Group 1.71

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Tasks

The scope of the working group "Realization of Acceleration" could be divided in three areas:

  1. Realization and dissemination of the quantities acceleration and angular acceleration, as well as quantities which can be derived from those like velocity, displacement, angular rate and angle of rotation. These quantities are realized and measured with national primary calibration facilities.
  2. The service of the calibration of transducers and measuring chains, which is basically the dissemination exercise. Here, the motion transducers of industrial or institutional customers are calibrated by using laser interferometriy.
  3. Research and development performed by the working group is focused on the optimization and extension of the measurement capabilities of the group. Hence R&D is basically done to support the aforementioned tasks.

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Research/Development

Realization of the units of acceleration, angular acceleration and derived motion quantities

The SI-units of acceleration and angular acceleration are realized at PTB by generating the respective sinussoidal, shock-shaped or other motion types with the national standard facilities and measuring them precisely by laser interferometry.

R&D in this area is typically targeted at an optimization of the mechanical or electrodynamic motion exciters with reference to the reduction of disturbing motion components or the extension of the measuring ranges. The latter concerns the available frequencies, amplitudes, shock intensities and durations.

In addition to the generation, the precise measurement of the motion over time is an essential part of the primary realization of the quantities in the working group. This is usually done by employing heterodyne laser interferometers which measure the motion displacement with reference to the wavelength of the He-Ne-laser. The methods for the analysis of the interferometric data is a matter of permanent development.

With all these developments the minimization of the measurement uncertainty is a primary goal.

Dissemination of units

For the purpose of the dissemination of the units, transucers are calibrated on the national standard facilities. Here the permanent process to keep up with rising demands of the customers is an R&D driver, too.

This, for example, is demonstrated by implemented new or improved data acquisition and analyis procedures, or in new or extended services for the quantitative characterisation of transducers with clearly defined and internationally accepted measurement uncertainties, reported in the calibration certificates.

The R&D results of the working group are typically published on scientific conferences like IMEKO or in peer reviewed journals.

If it is deemed usefull, the results of R&D will be introduced into new national or international standards.

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Services

Calibration

The task of disseminating the units is performed by primary calibration of customer's transducers or measuring chains. For that the working group offers the respective services covering a wide range with considerable small measuring uncertainties.

The applied methods comply with the respective international standards of the series of ISO 16063, specifically with the parts 11, 13, 15, 41 und 43

Details may be found in the  list of services of division 1 "Mechanics and Acoustics" of PTB in the section AUV (Acoustic, Ultra Sound, Vibration).

Assessment

The metrology infrastructure of Germany encompasses accredited calibration laboratories on its second level in the hierarchy below the PTB as national metrogy institute.
The accreditation is maintained by the German accreditation Body DAkkS. However, the technical supervision concerning the competenz, appropriate equipment and environmental conditions is delegated to technical experts doing respective technical assessments for the DAkkS in the accredited labs. On this acount several members of the working group are actively supporting the German system of accredited laboratories.

Assessments are performed on an international level as well. This happens for example during peer reviews, where the NMIs perform mutual assessments during on site visits. For this area too, the members of the working group receive frequent requests as recognized experts for their known experience in the field.

Consultancy

The members of the working group "Realization of Acceleration" are available to all parts of the society for consultations on the topic of vibration and shock metrogy and measurement.
Requests are welcome by phone during office hours or by email, any time.

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Information

The measurement and calibration capabilities of the working group are internationally accepted via the CIPM-MRA. The reported measurement uncertainties in the certificates are covered by respective records in the CMC-Datenbank at the BIPM.

In order to maintain this quality the working group took and takes part in several international key comparisons, many times leading them as pilot laboratory. The results prooved the competence of the work.

Beyond that the working group maintains many close international relationships with foreign partner NMIs in Europe and around the globe. This happens in personal bilateral contact as well as via international committees like CCAUV, EURAMET-TCAUV, IMEKO TC22, ISO TC108 etc. .

The R&D results and experiences with new or optimized procedures are disseminated in national and international guidelines. Examples here of are the parts 1, 11, 15, 41 und 43 of ISO 16063 guidelines of DAkkS-DKD-R 3-1, which were created under the auspices of PTB experts.

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