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K. Geva, H. Kahmann, C. Schlegel, R. Kumme
EXPERIMENTAL RESULTS OF MEASUREMENT HINGE FLEXURE STIFFNESS DETERMINATION

A hinge measurement flexure calibration set-up for stiffness measurements has been built at the Physikalisch-Technische Bundesanstalt (PTB) to estimate parasitic loads on PTB’s 5 MN·m torque standard machine (TSM). This paper describes the improvements made to a measurement flexure calibration set-up made since its first presentation. The list of measurement uncertainty influences is refined. Initial results of a combined transversal force and bending and torque moment stiffness measurement are presented and compared to a previous finite element analysis.

A. Prato, E. Giacardi, A. Facello, F. Mazzoleni, A. Germak
INFLUENCE OF PARASITIC COMPONENTS IN THE STATIC CALIBRATION OF UNIAXIAL FORCE TRANSDUCERS

Static calibration of uniaxial force transducers is performed with force standard machines which ideally generate a downward vertical force. However, these machines can be subjected to parasitic components, such as side forces and bending moments, which are transferred to the transducer under calibration. These components, mainly due to the not perfect verticality or alignment of the applied force, affect the calibration results, thus they should be estimated. In this work, parasitic side forces and bending moments are applied to six transducers by tilting and misaligning them with respect to the vertical gravitational force. Sensitivity coefficients of these parasitic components are obtained to be included in the uncertainty budget.

E. Webster, I. A. Robinson, H. Chong, S. Davidson
KIBBLE BALANCE FOR GRAM LEVEL MASS MEASUREMENTS

The redefinition of the kilogram in 2019 in terms of a fixed numerical value of a constant of nature, the Planck constant h, created the opportunity for the realisation of mass at any point on the scale and improvement in the uncertainty at sub gram scales. In this work, part of the route to measurement of mass at small scales at the National Physical Laboratory (NPL) will be described. The aim is to miniaturise a system based on the planned NPL “Next Generation” Kibble balance to a simplified gram level Kibble balance. This is a preparatory step for future work on a micro-electromechanical system (MEMS) scale Kibble balance.

I. A. Robinson
THE ARCHITECTURE OF THE NPL NEXT GENERATION KIBBLE BALANCE

This paper provides an overview of the architecture of the NPL “Next Generation” Kibble balance. The balance is intended to realise SI mass in the 100 g to 250 g range with an ultimate target uncertainty of one to two parts in 108. It is intended to be simpler to build and operate than previous generations of Kibble balance with the aim of allowing many more laboratories to participate in the realisation of a global mass scale.

P. Potgieter, S. Davidson, I. Robinson, J. Berry
DISSEMINATING FROM THE KIBBLE BALANCE TO INDUSTRY

The SI unit of mass, the kilogram, was redefined on 20 May 2019. The new definition is made in terms of the fixed numerical value of the Planck constant, h. The kilogram no longer takes traceability from the International Prototype of the kilogram and therefore a new system of traceability and dissemination must now be established to ensure reliable and repeatable measurements for industry. Two methods of dissemination will be compared and evaluated.

André Schäfer
ADVANCES IN THE DESIGN OF DMP41 - MEASUREMENT CHAINS USING EXAMPLES WITH TORQUE & MULTI-AXIS TRANSDUCERS

When evaluating the performance of measuring technology for mechanical quantities based on strain gauges (S.G.), one essential advantage is the possibility to realise smallest measurement uncertainties (MU).
In these applications, S.G. must be able coping with the further tightening of MU budgets. Thus, two advances in the determination of uncertainty of high precision measurement chains based on S.G., are discussed in here. The two uncertainty contributions, what are not always considered so far, are humidity influences and long term stability.
To support today’s sophisticated MU calculations, these two parameters have been further investigated and conclusions are drawn for each of measurement chain elements - reference transducers & precision amplifiers.

A. Prato, A. Schiavi, A. Facello, F. Mazzoleni, A. Germak
EFFECTS OF STRESS-STRAIN DATA SYNCHRONISATION ERRORS ON THE DETERMINATION OF YOUNG’S MODULUS OF HARD AND SOFT MATERIALS IN MATERIAL TESTING MACHINES

In this paper, the effects of stress-strain data synchronisation errors on Young’s modulus of hard and soft materials in typical material testing machines are described. Seven materials, three Cu Cr Zr alloys and four polymers, are tested in two machines conceived for the measurement of the mechanical properties of hard and soft materials. In both machines, the synchronisation of stress and strain signals are guaranteed by the machine’s internal signal processing system. By performing known temporal shifts with respect to each other, the Young’s modulus is calculated. In this way, the variation of Young’s modulus as a function of the temporal shift can be determined and the sensitivity coefficients, to be used in the uncertainty evaluation, derived.

N. Yogal, C. Lehrmann, Z. Song, P. Weidinger, R. Kumme, R. Oliveira
EFFICIENCY MEASUREMENT WITH A FOCUS ON THE INFLUENCE OF ROTATION AND TEMPERATURE ON TORQUE MEASUREMENTS PERFORMED ON SMALL-SCALE TEST BENCHES

Torque measurements that account for the influences of temperature and rotation are vital in determining the efficiency of rotating electrical machines on test benches. During experimental efficiency measurements, the influences of temperature and rotational speed generate errors in the torque measurements that could also affect the overall traceable efficiency measurement on test benches. In this paper, experimental efficiency mapping results with a focus on the influence of rotation and temperature on torque measurements are presented.

J. Sander, R. Kumme, F. Tegtmeier
CREEP CORRECTION METHOD FOR FORCE APPLICATIONS

This paper investigates the creep behaviour of a force transducer at different load levels. Using the results of fast-loading and creep tests, it presents a method for determining a creep correction factor. For this purpose, creep models based on exponentially decaying functions were applied along with an iterative algorithm that takes account of the history of the force-time profile.

H. Kahmann, K. Geva, C. Schlegel, R. Kumme, F. Härtig
FINAL DESIGN OF PTB’S 5 MN·m TORQUE STANDARD MACHINE WITH POSSIBLE FUTURE EXTENSION TO 20 MN·m

This paper describes the final design of the new 5 MN·m torque standard machine which is currently under installation at PTB in Germany. The machine can generate additional components for multi-component investigations and it is capable of applying - to a certain degree - dynamic torques. In the future, it can be extended to a maximum torque capacity of 20 MN·m.

Page 7 of 888 Results 61 - 70 of 8878