IMEKO Event Proceedings

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Takanori Yamazaki, Yoshiharu Sakurai, Hideo Ohnishi, Masaaki Kobayashi, Shigeru Kurosu
CONTINUOUS MASS MEASUREMENT IN CHECKWEIGHERS AND CONVEYOR BELT SCALES
This work is concerned with the development of a signal processing algorithm for checkweighers to realize much higher speed of operation and highly accurate measurement of mass of object during crossing a conveyor belt. Continuous measurement means that masses of discrete objects on a conveyor belt are determined in sequence. Checkweighers usually have maximum capacities of less than 75 kg and achieve measuring rates of 150 packages per minute and more. The output signals from the checkweighers are always contaminated with noises due to vibrations of the conveyor belt and the object in motion. In this paper an employed digital filter is of Finite-duration Impulse Response (FIR) type that can be designed under the consideration on the dynamics of checkweighers. The experimental results on checkweighers suggest that the filtering algorithm proposed in this paper is effective enough to practical applications.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Kazuhiro Kodama, Tomohide Kesamaru, Motoyuki Adachi, Kazuyuki Kamimura, Shigeru Kurosu
FORCE-MEASUREMENT USING GYROSCOPIC FORCE MEASURING SYSTEM
This paper concerns the development of an entirely new force sensor called Gyroscopic Force Measuring System (simply called GFMS) for measuring a force vectorially. In a previous paper, the dynamical characteristics and the error analysis of the GFMS for measuring a force vector in 3-dimensional space were examined using numerical simulations. The results of this work are directly applicable to design and construction of the GFMS. In this paper, the GFMS is constructed by a gyro-rotor used a miniature rate-gyro for aircraft instrument and mechanical parts together. In order to verify the principle of the GFMS, our prototype GFMS made on first trial is able to measure the only one component of a force vector, excluding servomechanisms to estimate angles of incidence. The feedback gains are selected somewhat arbitrarily, but the fundamental experiments show that the force less than 0.3 N can be measured by the GFMS. This suggests the possibility to measure a small force range useful for air-flow distribution in an air-conditioned room as an example of expected applications. No doubt the experimental results are to be released in a future publications.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

L. Doering, J. Frühauf, U. Brand
MICRO FORCE TRANSFER STANDARDS
The measurement of material properties and dimensional metrology are often carried out by mechanical probing using small spherical probing balls. Well-known instruments, such as microhardness measuring instruments, atomic force microscopes, stylus instruments and coordinate measuring machines operate in this way. With increasing miniaturisation and high precision requirements for measurement, these probing systems become ever finer, i.e. the radius of the probing spheres used becomes ever smaller. It therefore is necessary to increase the resolution and accuracy of the measurement. This reduction of the probing sphere diameter leads to the reduction of the probing forces required in order not to destroy the surface of the workpiece to be measured. Small probing forces are needed in particular, when soft materials are measured, i.e., in the ideal case, the probing force should be zero. In reality a force is, however, necessary to deflect the stylus tip and to ensure permanent contact between the stylus tip and object measured. These small probing forces below a few mN therefore have to be measured very exactly. For these purposes, different kinds of silicon bending beams or cantilevers, respectively, have been examined. Two types of micro force sensors were investigated: active and passive sensors. Passive sensors, which consist of calibrated bending beams can be used as micro force calibration standards. Active sensors also consist of Si bending beams but with integrated piezoresistive strain gauges for measuring the beam deflections during probing. Commercially available cantilevers, which were originally produced for application in atomic force microscopes and cantilevers manufactured by the Faculty of Electrical Engineering and Information Technology of the Chemnitz University of Technology were investigated as micro force transfer standards and sensors.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Kazunaga Ueda, Toshiyuki Hayashi, Koji Ohgushi, Hiroshi Maejima, Yukio Yamaguchi
A PROPOSAL OF AN EVALUATION METHOD OF UNCERTAINTY IN THE TRACEABILITY SYSTEM OF FORCE
This paper proposes a new approach for evaluating the uncertainty in the traceability system of force with the following features. a) Repeatability/reproducibility is evaluated by the Type A evaluation. b) Data taken in each orientation is treated with equality. c) Deviations from reference values and from the interpolation equation are considered to be equal to the standard deviation 1s of a normal distribution. d) Difference of the values in increasing load and in decreasing load are considered as a half-width of the possible distribution of values to be measured. The same is the case of difference of the zero points in a loading cycle.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Andrei Marinescu, Gheorghe Opran, Dorin Popa, Amritlal Sawla, Günther Haucke
STABILITY OF THE 32 MN FORCE CALIBRATION MACHINE AND INDUSTRIAL APPLICATIONS
In 1997 the High Force Calibration Laboratory from ICMET Craiova was accredited by DKD. The laboratory has a metrological test and calibration machine for the range 0.5 MN to 32 MN and the traceability to the German standard is ensured by means of periodic checks with 2 MN, 5 MN and 16 MN transfer standards of PTB and 2 MN and 10 MN transfer standards of ICMET. The paper contains a short presentation of the 32 MN machine, the results of its periodical checks performed within 1995-2002. A special attention is paid to the tests performed in 2001 with 2 MN and 16 MN PTB transfer standards according to EN 10000/3-94 and DKD procedure, as well as the tests of measuring equipment used in industrial applications. The aim of these tests was to check the long-term stability of the metrological performances of the machine reference measuring system.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

F. Tegtmeier, M. Peters
MULTICOMPONENT SENSOR FOR STRESS ANALYSIS IN BUILDINGS
An important element in the supervision of buildings is the necessary precise and continuous measurement of stress conditions. For this purpose, an encapsulated measuring sensor as developed which protects the sensitive strain-gauge technology within it and which can be easily inserted into measurement boreholes. The mechanical adaptation is effected by optimising a process of deformation of two conical bodies such that the envisaged measuring range covers the range of elastic deformation of construction steels. Suitable calibration procedures as well as measurement methods for the early detection of structural damage in buildings were developed for this adaptation model. A strain-gauge layout was devised for the sensor that is adapted to the specific local conditions, and the strain gauge is protected by a plastic seal. In order to be able to assess the lifetime of the sealing materials, which in part were being employed for the first time, the chemical/climatic building environment was simulated under forced conditions in the laboratory.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Claudia Santo, José Fuentes, Juan M. Curbelo
ESTIMATION OF UNCERTAINTY IN ANALYTICAL BALANCES - COMPARISON OF MASS MEASUREMENTS PERFORMED IN ANALYTICAL BALANCES (LATU-1999)
The current paper provides the details of the main sources of uncertainty that occur when conventional mass determinations are performed in analytical balances. The data presented correspond to the calibration of 18 analytical balances that belong to LATU, together with the detailed quantification of each of the sources of uncertainty. The results of a comparison of conventional mass measurement performed in those balances with a Teflon sample are assessed, considering their uncertainty values. Conclusions are subsequently drawn on conventional mass measurement's reproducibility in analytical balances in LATU.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

A. A. El-Sayed, H. M. El-Hakeem, B. Gloeckner, T. Allgeier
PERFORMANCE EVALUATION AND METROLOGICAL CHARACTERISTICS OF A DEADWEIGHT FORCE STANDARD MACHINE WITH SUBSTITUTE LOAD CONTROL SYSTEM
A new dead weight force standard machine covering the range from 5 kN to 500 kN direct weights has been designed and constructed at the National Institute for Standards (NIS)- Egypt, by Gassmann Theiss Messtechnik GmbH (GTM). The machine capacity can be duplicated to 1000 kN by means of a substitute force generator. The machine has been verified through a comprehensive Inter-laboratory Comparison Programme run over a period of two years at the Physikalisch-Technische Bundesanstalt (PTB) of Germany and NIS of Egypt. A well-selected set of high precision force transfer standards was used in the comparison calibration protocol. Rounds of measurements were carried out on deadweight machines at both the PTB and NIS. This paper presents the protocol followed to evaluate the metrological characteristics of the new machine as well as the Inter-laboratory Comparison scheme used in the verification process. The results prove that the machine achieve an uncertainty better than 2·10^-5 for calibration of force transducer by pure deadweights. Using the substitute force generator mechanism to double the machine capacity resulted in an uncertainty figure better than 1·10^-4.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Koji Ohgushi, Takashi Ota, Kazunaga Ueda, Eiji Furuta
DESIGN AND DEVELOPMENT OF 20 kN·m DEADWEIGHT TORQUE STANDARD MACHINE
A deadweight torque standard machine of rated capacity 20 kN·m (20 kN·m-DWTSM) was designed and developed, following the development of a 1 kN·m torque standard machine (1 kN·m-DWTSM) at NMIJ/AIST. This machine has a variety of features enabling it to perform precise measurements of torque, including double aerostatic bearings used in the form of a fulcrum. This paper outlines the torque standard machine.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Cezary Kaczmarek, Zdzislaw Kaczmarek
SENSORS OF IMPULSIVE FORCE AND PRESSURE WITH ONE POINT AND TWO POINT STRAIN MEASUREMENT APPLIED IN TASKS OF RECONSTRUCTION
In the paper the structure and the operating principle of impulsive force and pressure sensors applied in tasks of reconstruction is presented, which feature one point and two point measurement of the strain inside a Hopkinson bar type mechanical transducer. A comparison between the two versions of the sensor was carried out, taking into consideration the processing accuracy, the complexity of the conditioning circuit and the input signal processing circuit. The preferred application range is given for each version of the sensor.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

K. Baethke, M. Faulstich, G. Haucke, A. Dájer Espeleta
INVESTIGATION OF A NEW 1 MN FORCE CALIBRATION MACHINE OF TWIN CYLINDER DESIGN
Three new force calibration machines covering the range from 1 kN to 1 MN has been designed and constructed at DM-SIC in Bogotá, Columbia. The 1 MN force calibration machine (fcm) is a reference force calibration machine of new design. A special flexible sealed twin piston cylinder system with rotating cylinders has been used for the generation of hydraulic forces to reduce the friction, oil losses and pressure drops in the hydraulic system. Time optimization and a high accuracy of force control could be achieved by a three-step combination of rapid preliminary positioning, a PI controller algorithm and, finally, a changeover to PID controller characteristics. The relative deviations between the measurements carried out at PTB and the final measurements performed in the 1 MN reference force calibration machine show that the fcm fulfils the predetermined overall specifications limits of relative uncertainty < 2·10^-4 in the whole working range from 40 kN to 1 MN.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Boris Katz
A NEW WAY TO MINIMIZE UNCERTAINTY IN CALIBRATION PROCESS OF FORCE TESTING MACHINES
The results of the calibration of load cells (force transducers) according to ISO 376-1999 are described in table of values where force F (kN) is a function of electric signal R (mV/V) and by analytical approximation of the calibration curve. The analytical approximation is usually expressed by polynom of 2nd or 3rd degree. The measurement of force in the calibration of testing machines by means of digital unit device DMP-40 (HBM) suppose application of linear interpolation between two adjacent values of signal R. By means of mathematical calculations it is theoretically proven in which cases the linear interpolation is undesirable and leads to additional interpolation error, and increasing of the value of uncertainty measurement in accordance. A few studies and experiments of the issue confirm the theoretical conclusions: in some cases minimizing interpolation error and uncertainty measurement in measuring force F as a function of reading the signal R, can be achieved by approximation polynom instead of linear interpolation between two adjacent values. For this purpose QCC Hazorea has developed program called “MABA-2000,” which can solve this problem.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Andreas Subaric-Leitis, Christian Wöhry, Bernhard Seiffert, Christian Ullner
CHARACTERIZATION OF THE DYNAMIC BEHAVIOUR OF MATERIAL TESTING MACHINES
Material test results may depend strongly on the dynamic properties of the used testing machines. Unique methods and parameters for characterisation and validation of force or displacement controlled testing machines are still missing. In the presented paper a study of the control behaviour of a spindle driven uniaxial machine is carried out using a piezoelectric translator for generating the disturbance variable. The typical responses of the systematically optimized machine are compared to simulations of simplified controller systems. Some parameters concerning the time behaviour are discussed in terms of a systematic characterisation of the machine's dynamic properties and the experimental set up used.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Roman Schwartz, Andreas Lindau
THE NEW GRAVITY ZONE CONCEPT IN EUROPE FOR WEIGHING INSTRUMENTS UNDER LEGAL CONTROL
A new European gravity zone concept has been developed by WELMEC, the European Cooperation in Legal Metrology. This concept is independent of political or administrative borders and is accepted by all WELMEC member states regardless of existing national regulations concerning gravity zones. The new concept is based on gravity zones defined in terms of the geographical latitude φ and the height above sea level h, on a standardised gravity formula used for the adjustment of a weighing instrument to a reference gravity value, and on a uniform criterion for calculating the maximum permissible variation Δg/g within an individual gravity zone. The concept is of advantage especially for weighing instruments of class III. It offers an option that can, but must not be chosen by a manufacturer.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

L. Stenner, J. Andrae, R. Kumme, J. Mack
EXPERIENCE WITH A NEW CLASS OF FORCE TRANSFER STANDARDS
International force standard machines provide ever increasing accuracy. As a result the requirements for the force transducers used for international comparison measurements are also rising. The development of new force transducers shows that it is possible to reduce their measurement uncertainties. This paper describes the measuring bodies of these force transducers and the necessary selection method. The results of measurements obtained in force calibration machines and in force standard machines are presented.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Andreas Brüge
FAST TORQUE CALIBRATIONS USING CONTINUOUS PROCEDURES
Unlike step procedures, continuous procedures permit calibrations to be carried out within a very short time. In continuous calibrations the fast change in torque and thus also in the signals give rise to specific problems. This paper gives advice on how to limit the influence of the most important effects on the measurement uncertainty. A simulation method is introduced, which allows the contribution of the reference creep to the measurement uncertainty to be calculated.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Andre Zander, Rolf Kumme
ANALYSIS OF THE DYNAMIC TRANSMISSION BEHAVIOUR OF PIEZOELECTRIC FILM SENSORS
The goal of this analysis was to obtain knowledge about the dynamic transmission behaviour of piezoelectric film sensors based on Polyvinylidenefluoride (PVDF). Therefore a crossvalidation to the well-known behaviour of strain gauges based on constantan foils was conducted. The test equipment was composed of a shaker and a test piece with affixed sensors. The test piece was stressed through the connection to a load mass. The film sensors based on PVDF were mounted to the test piece in such a way that the load direction was parallel to the longitudinal axis of the PVDF-material. In this way it was guaranteed that the highest piezo strain constant d31 was mainly used. The output signals of the sensors were measured and the frequency response of the piezo film sensors in relation to the strain gauges were calculated. The results indicated that for frequencies above approx. 250 Hz the piezo film sensor frequency response modulus was a constant value with respect to the strain gauges and that for this frequency range there is the possibility to determine a specific transmission value of the used piezo film sensors similar to the “k-factor” of strain gauges. Furthermore, the high pass filter characteristic of the chosen charge amplifier could be identified.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Dieter Kenzler, Jörg Oblasser, Andreas Subaric-Leitis, Christian Ullner
UNCERTAINTY IN TORQUE CALIBRATION USING VERTICAL TORQUE AXIS ARRANGEMENT AND SYMMETRICAL TWO FORCE MEASUREMENT
Calibration machines up to a torque range of 20 kN·m need extensive design if the force is performed by dead weights. A machine based on two force reference standards and a vertical torque axis may serve to avoid these specific problems. The precision force transducers work at a lever arm of precision length. The test piece is mounted in vertical arrangement between a hydraulically operating rotary-actuator and the torque measuring system. Such a calibration machine allows additionally performing easily continuous calibration. Regarding an overall relative uncertainty not greater than 2·10^-4 there are some significant problems. The estimation of the uncertainty has been proved by comparative tests with the national torque standard by the PTB according to the guidelines EA-10/14 and EA-2/03.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Hans W. Werner, Emil Harreus
FORCE TRACEABILITY MEASUREMENTS TO ACHIEVE 0.005 % BEST MEASUREMENT CAPABILITY
The increasing accuracy of force transducers and their calibration had two major effects: the chance to better extract the capability of a reference standard machine (compared to a formerly mixed evaluation of machine plus transducer) and on the other hand the need to build up reference standard machines capable to calibrate those high precision transducers. Using the experience of designing force transducers, of constructing calibration machines and of calibrating force within the German Calibration Service (DKD) since 1977 HBM decided to take the challenge. Two new dead-weight force reference standard machines of 2.5 kN and 25 kN have been built up and their best measurement capability of significantly better than 0.01 % has been verified by transfer transducers from HBM´s product range.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

R. Kumme, O. Mack, B. Bill, Ch. Gossweiler, H. R. Haab
DYNAMIC PROPERTIES AND INVESTIGATIONS OF PIEZOELECTRIC FORCE MEASURING DEVICES
Piezoelectric measurement chains are widely used in many applications of dynamic force measurements, since these sensors offer a wide useable frequency range due to their high stiffness. Typical applications of piezoelectric force sensors are described in this paper. In general, the transducers are calibrated by quasistatic or continuous calibration methods. This contribution describes the dynamic properties of piezoelectric force measuring devices and methods to determine the dynamic response of the piezoelectric force measuring chain.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

D. Ratschko, C. Schlegel, F. Scholz, M. Gläser
MASS SPECTROSCOPY OF A MIXED XENON-GOLD ION BEAM
An analysis of an ion beam produced through sputtering of gold by means of Xenon ions in a CHORDIS ion source was performed. The composition of the extracted ion beam was investigated via mass spectroscopy using a double focussing dipole magnet. From the high resolution mass spectrum the abundance pattern of stable Xe isotopes was varified and the amount of charge transitions from 2+ → 1+ could be estimated. A maximum gold current of 0,8 mA directly behind the ion source was measured.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Oliver Mack
INVESTIGATION OF THE INFLUENCE OF DISTURBING COMPONENTS ON A PIEZOELECTRIC FORCE TRANSDUCER
For the measurement of the physical quantity force with conventional transducers it is assumed that the preferred direction of the force transducer is the same as that of the vector of the force. In practice this case is rarely being observed. Due to insufficient alignment of the transducer or of the measurement facility mechanically disturbing components such as bending moments, shear forces or additional axial forces occur which may influence the measurement result significantly. This paper deals with the investigation of the influence of static mechanical disturbing components on a piezoelectric force transducer. To determine a disturbing sensitivity of a piezoelectric force transducer different kinds of experimental setups are discussed. The measurement results show a characteristic direction depending disturbing sensitivity of piezoelectric force transducers, which is well known of piezoelectric accelerometers. The investigations point out that the influence of mechanical disturbing components on piezoelectric force transducers cannot be neglected for precision measurements.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Reinhold Vollmert, Günther Ramm
REALIZATION, MAINTENANCE AND DISSEMINATION OF THE MEASURAND "AC VOLTAGE RATIO IN MV/V" FOR STRAIN GAUGE MEASUREMENTS
Strain gauges allow the measurands force, pressure, torque or strain to be converted into voltage ratios and to be indicated by measuring amplifiers. Precision measurements are preferably carried out at 225 Hz and at voltage ratios of up to 2 mV/V. Bridge standards, which have to be traced back to national standards, are used for the electrical calibration of these measuring amplifiers. More than 15 years ago, in PTB the first measuring arrangement for this purpose has been developed and installed. The present contribution explains the traceability principle of bridge standards, shows the long-term stability of selected bridge standards on the basis of measurement results and brings first investigations into the interchangeability of measuring amplifiers up for discussion.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Udo Milz
DYNAMIC WEIGHING AND DOSING WITH FAST INTELLIGENT TRANSDUCERS FIT
We present new, weighing sensors with integrated electronics, specially optimized for dynamic weighing and dosing. There is already extensive signal processing in the transducer, with all the necessary functions for fast weight value acquisition and for full, local dosing control.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Thomas Allgeier, Ulrich Kolwinski, Daniel Schwind
JOCKEY-WEIGHT LEVER MACHINES FOR FORCE AND TORQUE
This paper describes a new type of standard machine, based on a travelling (jockey) weight moving along a lever which is supported on strain-controlled elastic hinges. It is equally applicable to the quantities force and torque. In addition to step-by step loading, the machine can perform continuous calibrations without having to rely on a reference transducer. Furthermore, testing through the zero load condition is possible with suitable mounting components. In the case of force machines, the jockey-weight design allows to tare the weight of all load introduction components, so that loads as low as 0.05 N can be applied without a reduction of accuracy. Design and operating principles of the standard machines are described, with particular emphasis on their application to modern calibration practices such as continuous calibration, together with some typical test results obtained so far.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Thomas Allgeier, Helmut Gassmann, Ulrich Kolwinski, Peter Giesecke
MULTI-COMPONENT MEASUREMENT TECHNOLOGY FOR FORCES AND MOMENTS
This paper introduces the requirements and possibilities of simultaneous force and moment measurements in industrial testing. Apart from describing the principal mechanics of force and moment vectors, important implications of ignoring disturbing components are mentioned. This is followed by an overview of practical applications of multicomponent measurements. The main part of the paper describes a new measurement tool for the data acquisition, evaluation and vector analysis. This comprises issues of transducer selection and applicability, details of the electronics used and also addresses the software design. Examples of typical applications of the entire system are given with an emphasis on outlining the mode of operation and ease of adaptation to new problems. Finally, the principles of system calibrations are described.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Günter Doemens, Dieter Spriegel, Hans Wünsche
MICROSYSTEM FOR CAPACITIVE FORCE AND TORQUE MEASUREMENT
In the fields of automation, drives and production engineering the measurement of force and torque is of particular importance for the monitoring and control of industrial processes. Today’s sensors applied for this purpose are mostly based on strain gauges with a limited range of applications. Reasons therefore are rooted in the short duty cycle, the poor overload safety and the complex mounting. In order to avoid the disadvantages mentioned an innovative micro-system based capacitive force and torque sensor has been developed. By attachment at two distinguished points the sensor is mountable in an easy and robust manner on static and rotating parts.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Douglas T. Smith, Shane Woody, Jon R. Pratt
COMPACT FORCE SENSORS FOR LOW-FORCE MECHANICAL PROBE CALIBRATION
The loading mechanisms of instrumented indentation machines are often calibrated using deadweights. In many cases, due to the geometry of the loading frame, the applied deadweight is tensile, while the indentation loads to be measured are compressive. In this paper, we report preliminary efforts to develop a compressive load cell for use on a typical instrumented indentation machine. Two devices were evaluated, one a compact capacitance-based device (fabricated at the National Institute of Standards and Technology), the other a piezoresistive force sensor. We will describe the calibration sensitivity, stability and drift of each, and discuss the potential use of each as a force transfer artifact for the calibration of instrumented indenters.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

John A. Kramar, David B. Newell, Jon R. Pratt
NIST ELECTROSTATIC FORCE BALANCE EXPERIMENT
We have designed and built a prototype electrostatic force balance for realizing forces in the micronewton range. The active electrodes are concentric cylinders, the outer serving as the reference and the inner suspended and guided by a rectilinear flexure mechanism. The geometry has been designed such that a near-linear capacitance gradient of 1 pF/mm is achieved at a working overlap of 5 mm. We have used this balance in a null-displacement mode to compare an electric realization of force with the force generated by calibrated deadweights of nominal mass 1 mg, 10 mg, and 20 mg. The preliminary measurements reported here agree to within a few parts in 10⁴ after including all known correction factors.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Jon R. Pratt, David B. Newell, John A. Kramar
A FLEXURE BALANCE WITH ADJUSTABLE RESTORING TORQUE FOR NANONEWTON FORCE MEASUREMENT
The NIST electrostatic force balance compares mechanical probe forces to an SI realization of force derived from measurements of the capacitance gradient and voltage in an electronic null balance. As we approach the nanonewton regime, the finite stiffness of the guiding flexure in the balance becomes a limiting factor. Here, we consider an equal arm balance mechanism constructed using flexure pivots as an alternative to the compound rectilinear spring of the present design. We review how the sensitivity of such mechanisms can be adjusted either by manipulating the center of gravity, or by applying a negative restoring torque using a spring. We examine tradeoffs associated with tuning the stiffness of these mechanisms with regards to tilt sensitivity and various nonideal flexure behaviors. Results obtained with a prototype mechanism are presented.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Weilu Shang, Yan Wang, Tao Li, Zhaojun Qian, Dongsheng Zhang, Mingbang Lin
ELIMINATING THE ADDITIONAL INERTIA IN MEASURING THE NATURAL FREQUENCY OF A TORQUE SENSOR
In measuring the natural frequency of a torque sensor, one must apply excitation through some mechanism which produces additional inertia coupling to sensor that the original or instinct data can not be gotten. A method was developed which can eliminate these inertia by testing and calculating. The principle, experimental method, instrumentation and results were described in detail in this paper.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Dan Mihai Stefanescu, Tiberiu Manescu
MULTI-COMPONENT FORCE AND TORQUE BALANCES FOR WIND TUNNELS
Starting from the German experience in the field of electrical measurement of mechanical quantities, one of the top application is the six-component measuring of the aerodynamic load torsor. For these complicated mechatronic devices, which have to measure six widely different components with the same relative accuracy, a complex mechanical and electrical analysis has been performed concerning the optimum positioning and connecting of the strain gauges, in order to increase the sensitivity and to compensate the disturbing influences. Four original strain gauged multicomponent balances for scale model testing were designed and manufactured having in view the improvement of the road vehicle and aircraft performances. Concrete data are shown in the four figures and tabularly summarized.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Andreas Lindau, Rolf Kumme, Andrea Heiker
INVESTIGATION IN THE LOCAL GRAVITY FIELD OF A FORCE LABORATORY OF PTB
It belongs to the functions of the National Institutes of Metrology to realise a force scale of highest accuracy. The uncertainty of the resulting force basically depends on the precise knowledge of local gravity acceleration. This paper describes the spatial determination of the local gravity field in the force laboratory of the PTB on the basis of a new highly precise gravity network. A special emphasis is placed on the influence due to gravity of the surrounding masses placed in the laboratory on the single gravity value. It can be shown that the installation of the new 2 MN deadweight force standard machine has led to a significant change in the local gravity field. Temporal variations caused by earth tides are proved by long-term registrations and are considered in a correction term for the gravity value. The periodical change of gravity reaches a level of 10^-7 g in the equator region and at present does not affect the uncertainty budget of the force measurement.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Leonardo D’Acquisto, Roberto Montanini
DESIGN AND SET-UP OF A BI-PENDULUM IMPACT TESTING MACHINE
In this work the design and set-up of a bi-pendulum testing rig able to perform low-velocity impact measurements on small and medium-size components is reported. Experimental tests were conducted both to check the theoretically calculated value of the equivalent impacting mass and to quantify the overall energy losses during the idle movement of the mass. In order to provide useful information on the material behaviour during a crash test, the impact testing machine has been instrumented with different sensors: a piezoelectric accelerometer placed on the impact mass to measure the horizontal acceleration, an optical sensor to measure the initial impact velocity, a piezo film load cell, developed by the Authors, placed on the sample holder block, to measure the impact force directly on the specimen.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Jongho Kim, Yonkyu Park, Daeim Kang
DESIGN AND FABRICATION OF A THREE-COMPONENT FORCE SENSOR USING MICROMACHINING TECHNOLOGY
This paper describes a design methodology of a tri-axial silicon-based force sensor with square membrane by using micromachining technology (MEMS). The sensor has a maximum force range of 5 N and a minimum force range of 0.1 N in the three-axis directions. A simple beam theory was adopted to design the shape of the micro-force sensor. Also the optimal positions of piezoresistors were determined by the strain distribution obtained from the commercial finite element analysis program, ANSYS. The Wheatstone bridge circuits were designed to consider the sensitivity of the force sensor and its temperature compensation. Finally the process for microfabrication was designed using micromachining technology.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Miroslav Kopecky, Ivan Letko, Vladimir Cuth, Jan Vavro
TESTING EQUIPMENT FOR FATIGUE TESTS OF STEEL CORDS
The contents of the paper point out the necessity of combining the theoretical and experimental approaches in the investigation of tyre load in vehicles. The models are planar and they model the cross-section of the tyre enabling the consideration of the bottom load and the internal pressure in the tyre, as well as the influence of the lateral force. The paper presents the findings, the formulations necessary for solving the task obtained in the experimental model tests and serving as a basis for comparison with the results obtained from purely theoretical approaches, e.g. by the method of finite elements, with identical load conditions.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Jin-Wan Chung, Kyung-Ho Chang, Woo-Gab Lee, Kwang-Pyo Kim
AIR DENSITY DETERMINATION USING 1 KG BUOYANCY MASS COMPARISON(III)
In calibration of secondary 1 kg stainless steel mass standard from a platinum-iridium kilogram prototype, a major uncertainty arises from the measurement of air density for the buoyancy correction. This paper is continued to the reference. An experimental determination of air density using buoyancy pairs and a vacuum balance has been carried out and its results were compared with those of the CIPM formula 81/91. The environmental measurement instruments used for this experiment are different from those previously used. Also the true mass difference between buoyancy pairs in vacuum was measured at mass laboratory of NMIJ in Japan and compared with the KRISS result. The disagreement between air density measurements by the 1 kg BA-pair and those by CIPM formula is 5.1 x 10^-4 kg/m³, but the standard deviation of the difference between both methods has been improved, to 5.3 x 10^-5 kg/m³ compared to 1.5 x 10^-4 kg/m³ by the previous experiment.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Kamlesh K. Jain, S.K. Jain
BEST MEASUREMENT CAPABILITY OF THE NEWLY DEVELOPED 5 kN DEAD WEIGHT FORCE MACHINE
This paper describes the salient features and the results of metrological performance of the newly developed 5 kN dead weight force calibration machine. Two well characterized strain gauge force transfer standards of 2 and 5 kN full capacity having repeatability better than 0.002% in compression mode were used to derive the best measurement capability of ± 50 ppm (k = 2) of the machine.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Carlo Ferrero, Carlo Marinari
THE DISSEMINATION OF THE FORCE UNIT IN ITALY: CALIBRATION OF MATERIAL TESTING MACHINE INTERCOMPARISON
One of the most important activities at European (EA) and National level of the National Accreditation Body (NAB) is the organisation of a series of interlaboratory comparisons (ILC), to verify the measurements capability of the calibration laboratories. In 2001 one ILC, for the calibration of uniaxial testing machines, was organised in Italy by SITIMGC with the IMGC-CNR as reference laboratory. In the present paper the main results obtained during the ILC are discussed, in particular a regression analysis was applied to evaluate the differences on the repeatability and accuracy given by the different laboratories.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

C. Ferrero, C. Marinari
CHARACTERISATION OF REFERENCE TORQUE WRENCHES BY THE IMGC SIX-COMPONENT CALIBRATION SYSTEM
This paper describes the metrological characterisation of two Reference Torque Wrenches (RTW) of 100Nm and 500Nm capacity. The characteristics of the torque sensors were evaluated by using the IMGC-CNR sixcomponent calibration system (EUROMET agree facility, project 113). The repeatability of the absolute variation of the output signal of the two TTS under the application of the different spurious components, referred to the R.O., is in general of the order of 5·10^–5. The sensitivity to spurious components are normally better than 2·10^–3 of the nominal torque.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Željko Alar, Mladen Franz
TRACEABILITY IN FORCE MEASUREMENT IN REPUBLIC OF CROATIA
In this study, based on results of the previously performed calibrations and factory specifications, an analysis of force measurement equipment in Republic of Croatia has been done. Transfer force standards of the Laboratory for Testing Mechanical Properties ( LIMS) have been calibrated in HBM, Germany. Calibration curves for specific transfer standards were obtained, to be used for estimation of standard uncertainties. Also, expanded measurement uncertainty was calculated at each measuring point, according to the document EA-4/15. This was used for determining the best measuring capability of the Laboratory, as well as for developing of the equipment calibration scheme for force measurement in Croatia. The previous and last calibration results for the same transfer standards were compared and, further to it, certain conclusions were made on how characteristics of the standards are influenced by use during certain period of time.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Heikki Kajastie, Jorma Manninen, Kari Riski
DENSITY CALIBRATIONS AT MIKES
The density measurement instruments at MIKES will be described. Also a construction of a instrument for weights 1 g – 200 g will be presented. The main test results will be given.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Jorge C. Torres-Guzmán, Amritlal Sawla, Daniel Ramírez-Ahedo
FORCE STANDARDS COMPARISON BETWEEN PTB (GERMANY) AND CENAM (MEXICO)
A force comparison was carried out between the Centro Nacional de Metrología, CENAM (in Mexico) and the Physikalisch-Technische Bundesanstalt, PTB (in Germany), in order to estimate the level of agreement for the realization of the quantity and the uncertainty associated to its measurement. The comparison was carried out in a range starting at 2 kN and up to 150 kN. In order to achieve best accuracy of the force transducers used was made of 5 sub ranges (5 kN, 20 kN, 50 kN, 100 kN and 150 kN). The results obtained, the deviations graphs that include the uncertainty for each laboratory are presented in this document.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Yon-Kyu Park, Rolf Kumme, Dae-Im Kang
DYNAMIC INVESTIGATION OF MULTI-COMPONENT FORCE SENSORS USING HARMONIC EXCITATION
This paper describes the dynamic investigation of a 3-component and a 6-component forcemoment sensors using the facilities in the PTB (Physikalisch-Technische Bundesanstalt) in Germany. The 3-component sensor has the transverse forces Fx and Fy of each having 200 N capacity and a twisting moment M_z of 10 N·m capacity and the 6-component sensor has force components F_x, F_y and F_z each having 200 N capacity and moment components M_x, M_y and M_z each having 20 Nm capacity. The sensitivity of the sensors decreases as the frequency increases and the sensors show almost 90o symmetry due to their geometry.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Jong-Ryeol Noh, Jae-Young Jeon
DEVELOPMENT AND EVALUATION OF 6-COMPONENT LOAD CELL FOR LAND-BASED TEST OF HELICOPTER ROTOR DYNAMICS
A 6-component force transducer was developed and evaluated for small-scale model test of helicopter rotor dynamics. The evaluation of the transducer was done mainly through interference check using multi-component calibration procedures. In this paper, the design and analysis process and the related results are verified through calibration results. The force transducer was designed to fix to rotating hub, and dominant force component was lifting force with maximum 1000 lb. From rotating characteristics, fail-safe structure was required to prevent the rotor from bursting out in case of rotor failure. The sensing element was designed with structural symmetry for selfcompensation by full bridge circuit and the expected deformation was analyzed by using finite element method.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

C. Dogan, O. Akkoyunlu, C. Kuzu
DEVELOPMENT OF THE 1 kN·m STATIC TORQUE STANDARD MACHINE AT UME
In the last decade, the increase in the need for the accuracy of the torque metrology created an obligation to produce a new torque standard machine for precise measurement of torque. This paper summarizes the torque standard machine designed and manufactured at UME with the range from 2 N·m up to 1 kN·m. In this machine torque is realized by a lever-mass system. Nominal force arm length of the lever is 0.5 m and constant. In each side of the lever, there are 6 different weight sets; and each set is containing 13 individual mass-stacks. For minimizing the torque loss at fulcrum an aerostatic bearing is used, and the change in the lever position due to the dead weights loading is corrected.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Aimo Pusa
TRACEABILITY OF THE CALIBRATION OF TEST CAR FOR ROLL BRAKE TESTER
The calibration of the roll brake tester for trucks has been made general by direct loading of the force transducer. That means to ignore the complete force transmission to rollers, which are in contact to trucks wheel. To be able calibrate exactly the braking force the Finnish institute YTOL has developed a test car to measure direct this braking force. The car has an extra axle with free rotating wheels and braking equipments as well the torque measuring devices. The axle can be moved in vertical position to have the weight maximum 4000 kg on the axle. Raute-MIKES had the task to realise the calibration of this measurement device. The calibration has been made with a 20 kN·m reference torque transducer, which is calibrated static by PTB. The calibration of the brake measurement system has been made as dynamic with the speed of braking as static.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Paul Hohmann
CONCEPT OF A TORQUE CALIBRATION UNIT FOR LOW RANGES BASED ON AIR BEARING COMBINATION
The need to calibrate torque in low ranges is given in case of dentist tools, viscometry or friction measurement in ball bearings. Ranges starting about 0,005 N·m as an example, is the target of the following description. A theoretic possibility is shown how to handle all disturbing influences in using mass beam systems as a basic quantity.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

Biserka Mladinic, Tijana Parlic-Risovic
ADDITIONAL CONTROL OF AMBIENT CONDITIONS IN MASS METROLOGY AND ITS INFLUENCE ON MEASUREMENT QUALITY
Mass determination by use of mass comparators is influenced by different parameters including the conditions of ambient air. Having a look at the temperature of weights and the gravitational field gradients, the relatively small impact of these parameters on mass determination can be easily determined on the base of reproducible measurement results. Of metrological interest is the air density determination and control during a measurement series that could be used to improve the quality of measurement. The influence of temperature change as a function of time and its control simultaneously during the weighting process is discussed. The implementation and use of small climate chambers around the mass comparators to smooth out the temperature and relative moisture variations is described and discussed.
18th Conference on Force, Mass and Torque, Celle, Germany, 2002

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