9762 papers found
A combination of both quantities force and torque together are often necessary. Some examples are given in testing ship propellers, or in case of fixing screws. Also in elastic axle bearings both quantities are working and both should be measured while happened together. The measurement equipment in the test rigs should be traceable. Therefore a transfer measurement equipment is needed which is calibrated by similar procedure as it is used.
A mathematical model of the magnetic interaction between a weighing instrument and a weight and measurements of the distribution of the magnetic field in the space above a top loading weighing instrument are presented. Four parameters have been evaluated that characterize sufficiently well the magnetic property of the instrument, provided the weight's magnetic susceptibility and magnetization are homogeneously distributed over its volume. The magnetic field of the weighing instrument is modelled by a magnetic dipole field. The integration over the weight's volume was made by stepwise...
GTM have developed a primary torque standard which covers the range from 1 Nm to 1 kNm with a single load frame and only one weight stack per direction of operation. The design comprises a double-sided lever, supported on straincontrolled elastic hinges, a binary weight stack of exchange disk design for each direction, mounting accessories for the transducer under test and a counter-torque drive with servo-controller. Compared to conventional types with air bearings and a multitude of several stacks, the chosen design offers distinctive advantages: Higher reliability of the lever support,...
A method for measuring the impact response of force transducers is proposed. In this method, a mass is made to collide with a force transducer, and the instantaneous value of the force acting on the sensing point of the transducers is determined by measuring the instantaneous value of the acceleration of the inertial mass. To realize linear motion with sufficiently low friction acting on the mass, a pneumatic linear bearing is used, and the velocity of the mass, the moving part of the bearing, is measured using an optical interferometer. An impact force with half value width of approximately...
A new superconducting levitated-mass system is now being developed with the final target of replacing the kilogram in terms of the fundamental constants. Improving the stability of trajectory by means of introducing a superconducting linear bearing is the issue in question for the first stage of this development. The present status of the development, experimental results and further prospects are discussed.
Magnetoelastic transducers are classed among the inductive transducers in which the relative permeability of ferromagnetic materials suffers changes under the effect of mechanical load. The change (always of anisotropic character) in the relative permeability results in a change in the impedance of the coil located in the transducer and, in case of several coils, a change in the transfer impedance as well. This paper describes the phases of planning the magnetoelastic transducers in detail, starting from the mechanical load up to the electric output signal. For the planning, the knowledge of...
The establishment of national calibration services (NCS) and mutual agreements between the NCS of the different countries (UKAS, DKD, SIT, etc.) have increased the necessity of the dissemination of the unit of force inside the individual countries and of standards harmonisation through continuous international comparison. In the paper the new primary standards of 30 kN and 1 MN of the CNR-IMGC are described. Results are given concerning: the evaluation of the internal coherence of the machine; the internal comparison in the laboratory; the dissemination of the force unit in Italy.
Ion Projection Lithography being one of the New Generation Lithography (NGL) techniques, uses Silicon stencil masks. A typical 150 mm stencil mask consists of a thin membrane of 126 mm diameter containing the openings for lithography and a stiff outer ring of bulk wafer material. The thickness of the membrane is in the order of several microns. The membrane has intrinsic stress to keep it flat. To determine the stress of the mask membrane the well known bulging method is used. In the developed equipment an electrostatic force between the membrane and a second electrode replaces the...
The measurement of air density is crucial for any high accuracy mass calibration and is of particular importance when comparing weights of dissimilar materials such as stainless steel and platinum iridium. The current limit of accuracy to which air density can be determined is the major source of uncertainty in the dissemination of the mass scale for the majority of National Measurement Institutes. Until fairly recently the main method for the determination of air density was by calculation from measurements of temperature, pressure and humidity using the equation recommended by the CIPM...
Based on acapacitive angle/angular speed sensor a sensor measuring the torque on a rotating shaft has been developed. The torsion resulting from the torque on the shaft is measured by two rotatable electro desplaced between two sensor plates. The relative angle between the two rotors is calculated from measurements of the capacitive coupling between different transmitting stator segments. A prototype of this sensor has been developed with a range of the torque of ± 2 N·m with a measurement error of 0.04 N·m and a resolution of 0.02 N·m.