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Realization of Acceleration

Working Group 1.71

Profile

The working group "Realization of Acceleration" operates in the following fields:

- the quantities acceleration and angular acceleration
- the derived quantities speed and angular speed
- the time-dependent displacement and rotation angle
- impact force and dynamic force

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

  1. Realization and dissemination of the quantities. These quantities are realized and measured with national primary calibration facilities.
  2. Calibration service of sensors, measuring chains and measuring devices for translational and rotational motion quantities derived from the tasks mentioned above. With these services, appropriate industrial devices are calibrated by research facilities or other metrology institutes using laser interferometriy.
  3. Research and development are focused on the optimisation and extension of the measurement capabilities of the working group. These activities are basically done to support the before-mentioned area of operations.

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Research/Development

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

The SI-units 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 especially to reduce the disturbing motion components or the extension of the measuring ranges. The latter considers the available frequencies, amplitudes, shock intensities and durations.
In addition to the generation, the precise measurement of the motion over time with laser interferometry is an essential part of the primary realization of the quantities. This is usually done by employing heterodyne laser interferometers which measure the motion displacement with reference to the wavelength of the laser. The methods for the analysis of the interferometric data are a matter of permanent development.
Among other things the working group is researching the dynamic feedback of bridge amplifiers and pick up electronics of strain gauge-based pickups in cooperation with the working group 2.12 Ratio Measurements and Impedance.
With all these developments the minimization of the measurement uncertainty is a primary goal.

European metrology research programme (EMPIR)

At the moment the working group is studying on the european research project InfraAUV which belongs to an EMPIR programme. This means working on low-frequency vibration measurement, underwater and airborne infrasound measurement, specifically in the filed of calibration of seismic sensors. For this purpose, the current measuring range shoud be extended to very low frequencies with - at the same time - small amplitudes. Procedures for the on-site calibration of seismometers should be developed. Please follow this link for more information.

Research and development in the field of impact forces, as well as in the field of dynamic torque, were carried out within the scope of the previous programme EMRP in the research project dynamic measurement of mechanical quantities together with eight other european metrology institutes.
The dynamic properties of the sensors in interaction with the used calibration devices are described with the help of models, which contribute significantly to an improved knowledge of the dynamic measurement behaviour for the dissemination of the units.
The results of this research project are published in PTB news, edition 02/2015 and are available on PTB website.

Dissemination of units

For the purpose of the dissemination of the units, transducers are calibrated on the national standard facilities. The measurement possibilities are permanently adapted to the rising demands of the customers.
This, for example, is demonstrated by implemented new or improved data acquisition and analysis procedures, or in new or extended services for the quantitative characterization of transducers with clearly defined and internationally accepted measurement uncertainties, reported in the calibration certificates.
New developments and R&D results of the working group are typically published in scientific journals and are reported on conferences.
After successful testing, new processes may be introduced into the standardization in order to standardize the methods that are well-known in Germany internationally.

Publications

Here you will find the list of publications of the working group Realization of Acceleration.

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Services

Calibration

The task of disseminating the units is performed by primary calibration of customer's transducers or measuring chains. 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 institutes.
The accreditation is maintained by the German accreditation Body DAkkS. However, the technical supervision concerning the competence, appropriate equipment and environmental conditions is delegated to technical experts doing respective technical assessments for the DAkkS in the accredited labs. 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. In this area 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 prove 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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