Development and calibration of a 500 kN six-component dynamometer

European Commission Directorate-General For The Information Society And Media Directorate-General For Research And Innovation

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Industrial research and development

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• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-THE-INFORMATION-SOCIETY-AND-MEDIA-DI
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• Langue: English
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Commission of the European Communities
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APPLIED METROLOGY
DEVELOPMENT AND CALIBRATION
OF A 500 KN SIX-COMPONENT DYNAMOMETER
Report
EUR 14838 EN
Blow-up from microfiche original Commission of the European Communities
ber information
APPLIED METROLOGY
DEVELOPMENT AND CALIBRATION
OF A 500 KN SIX-COMPONENT DYNAMOMETER
C. FERRERÒ, LI QING ZHONG, C. MARINARI, E. MARTINO
Istituto di Metrologia "G. Colonnetti"
Strada delle Cacce 73
1-10135 Torino
Contract No 3291/1/0/062/89/4-BCR-l (30)
FINAL REPORT
Directorate-General
Science, Research and Development PARL EUROP. Biblioth.
N.CEUR14838E 1993 Ï
i^tJjLll\% ÜIL Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General XIII
Telecommunication·, Information Market and Exploitation of Research
L-2920 LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on behalf
of the Commission is responsible for the use which might be made of the following information
This document has been reproduced from the best original available
Catalogue number: CD-NA-14838-EN-C
ECSC — EEC — EAEC. Brussels · Luxembourg, 1993 TABLE OF CONTENTS
ABSTRACT V
1.INTRODUCTION1
2.GENERAL EVALUATION OF MULTICOMPONENT DYNAMOMETERS2
2.1 Single-block dynamometers 2
2.2Compositedynamometer2
3. COMPLETE DYNAMOMETERSTRUCTURE3
4.UPPER SUPPORTPLATE(USP)4
5. CROSSED-FLEXURE PIVOT4
5.1 Design calculations5
5.2Calculation with the finite-element method 6
5.3 Steel selection and experimentaltestsθ
5.3.1 The first-generationprototypeofacrossed-flexure pivot ... 9
5.3.2 The second-generationcrossedflexurepivot prototype 9
5.3.3 Measurement of displacementof crossed-flexure pivots
under lateral loads 9
5.3.4 CharacterizationoftheHBMZ4-200 kN connectedwithtwo
crossed-flexure-pivots10
6. EQUIPMENT 11
6.1The six-componentdynamometer11
6.2Measurement chain11
6.3Electric connecting wiring11
7.MULTICOMPONENT CALIBRATION SYSTEMS 12
7.1 The IMGC 6-componentcalibrationsystems12
7.1.1 The IMGC-F2multicomponent calibration system13
7.1.2 The IMGC-F4t calibration system14
8. DESCRIPTION OF FORCE STANDARD MACHINES14
8.1 The IMGC deadweight machine 14
8.2The IMGC 1 MN hydraulic machine14
8.2.1 Referencestandarddynamometer: characterization
of HBMZ12loadcellsandcomparison betweenPTB
andIMGCresults15
9. CALIBRATION METHODS 15
9.1Thesequentialmethod16
10. TESTINGPROGRAMME16
11.AXIAL FORCE COMPONENT17
11.1Analysis of results17
11.1.1 Repeatability 17
III 11.1.2 Reproducibility 17
11.1.3 Influence of variations in ambient conditions 18
12. TRANSVERSE FORCE COMPONENTS AND MOMENTS 1
12.1 Matrix of sensitivity coefficients
12.2 Linearity9
12.3 Repeatability 20
12.4 Hysteresis
12.5 Elastic deformation
13. CONCLUSIONS
REFERENCES '.1
TABLES 23
IV ABSTRACT
Several international comparisons of primary force standard
machines showed that the measured axial force value may be
affected by an uncertainty often higher by one order of magnitude
than the uncertainty which could be expected on the basis of the
relative uncertainties of the values of mass, of the acceleration
due to gravity, and of buoyancy.
The main cause of such discrepancy is to be found in the
parasitic effects (transverse forces and moments) which are
always present side by side with the axial force in the different
standards.
In order to investigate the parasitic components, which could
cause rotation effects and overlapping, a six-component
dynamometer was developed by IMGC, and a four component by ONERA.
Ten deadweight force standard machines (DWM) six belonging to
countries of the European Communities (NPL, TNO, PTB, LNE, IMGC),
two to China (NIM) and two to Japan (NRLM) were checked by means
of the IMGC dynamometer from 1982 to 1988.
The four standard machines of NPL, TNO, IMGC, LNE were checked
also by means of the ONERA 4-component dynamometer, with the aim
of bringing into evidence a possible influence of the different
stiffness of the two dynamometers on the metrologicai
characteristics of these standard machines, as well as the
repeatability and the reproducibility both of primary force
standards and transfer standard dynamometers.
The IMGC composite 100 kN six-component dynamometer proved to be
a powerful diagnostic tool to detect possible contact points
along the load transmission line. Moreover it has the advantage
of low coefficients for component interaction and of
insensitivity to support and load-application conditions, all
this meaning high repeatability and reproducibility, and,
consequently, a low machine - dynamometern (rotation
effect).
Given the results previous obtained with the 100 kN IMGC 6-
component dynamometer, the BCR of the European Communities has
financed a new project for the realization o i a 0-componen t
dynamometer with 0.5 MN rated load.
The report describes the design principles and the main elements
of the 6-component 500 kN axial load dynamometer designed and
constructed by IMGC. This instrument is of the composite typed
is made up of six separate load cells, three of them measuring the axial forco Ζ and the two bonding moments L and M. Decoupling
with respect to transverse compononts is obtained by means of
gimbols consisting of integral double elastic flexures, the other
three load cells make it possible to measure the transverse
components X and Y, and the twisting moment N.
The individual elements were tested by determining their
stiffness and elongation, with 250% to 300% overload.
The three measuring chains for axial force, each represented by a
HBM-200 kN dynamometer and by two crossed-flexure pivots, were
checked with the IMGC 1Q0 kN deadweight machine (DWM) and with
the IMGC 1 MN hydraulic-amplification machine. Repeatability and
reproducibility on the IMGC DWM are both 1*10~5/FS, the rotation
effect is 2*10~5.
Λ description is given of the multicomponent calibration systems
adopted for the determination of the metrological characteristics
and of the sensitivity matrix of the 6-component 0.5 MN
dynamometer. The two systems in question are constructed around
the two IMGC force standard machines.
Planarity and orthogonality of horizontal forcas can be
determined optically by suitable topographic operations to within
1*10"4 rad.
The overall behaviour of the 6-component dynamometer can be
summarized as follows:
Very high sensitivity to compression force Ζ (4800000 digits
with 5 digits of resolution as regards the sum of signals
from the three VI, V2, and V3 load cells).
Good sensitivity to other components, in particular to the
twisting moment; sensitivity to side components is about 80
digit/N with component X and Y; sensitivity to the bending
moment is 08 digit/N*m with moment L and 100 digit/N*m with t M; sensitivity to twisting moment Ν is 300 digit/N*m.
Sensitivity to different components (side forces and moments)
makes it possible to bring to light tilting and bending
moments corresponding to displacements of axial load (to the
reference axis of the dynamometer) of 1 μιη at the rated
capacity.
VI 1. INTRODUCTION
Any improvement in primary and transfer standards is an
improvement in the whole hierarchical system of force measuring
devices and is consequently converted into greater reliability in
industrial production. Substantial progress in the sector of
force standards can be made through the measurement of parasitic
components as functions of various parameters in order to bring
the sources of error under control, and take effective remedial
steps.
International comparisons were previously carried out with
single-component load cells (Debnam and Wieringa, 1974; Sawla et
al, 1977; Jenkins and Debnam, 1982). These comparisons, which
evidenced a rotational effect and overlapping phenomena caused by
the interaction of the cells with the machines, made great
improvements possible as regards reduction of the uncertainty in
axial load determination (from a few 10"4 to some parts in 10^)
and showed that a multi component dynamometer (Bray et al, 1978;
Dubois et al, 1980) is an essential tool in order to improve
force standard deadweight machines, to attempt to explain
anomalies, to optimise testing methods, and to give manufacturers
indications allowing them to improve both force machines and load
cells.
In order to investigate the parasitic components, which could
cause a rotation effect and overlapping, a six-component
dynamometer was developed by IMGC, and a four component by ONERA.
Ten deadweight force standard machines (DWM) six belonging to
countries of the European Communities (NPL, TNO, PTB, LNE, IMGC),
two to China (NIM) and two to Japan (NRLM) were checked by means
of the IMGC dynamometer from 1982 to 1988.
Rotation effects and eccentricity of the point of axial-load
application was carefully analyzed, with a view to evaluating and
reducing when possible, their influence on measurement accuracy.
The