9762 papers found
A measurement system of air density that for high accuracy measurement of measuring weights is developed base on the CIPM-2007 equation. Measurements of temperature, humidity, CO 2 , pressure and air density are performed by this system automatically. The experimental results prove that measurement accuracy of measuring weights can be improved by using this system process air buoyancy correction.
In this research we develop a high speed mass measurement system with conveyor belt (a checkweigher). The objective in this paper is to propose a dynamic model of the measurement system. The checkweigher with electromagnetic force compensation can be approximated by the spring-mass-damper systems as the physical model, and an equation of motion is derived. The model parameters can be obtained from the experimental data. Finally, the validity of the proposed model can be confirmed by comparison of the simulation results with the realistic responses. The dynamic model obtained offers practical...
The demand for lower uncertainties in force measurement is increasing. Deadweight force standard machines are known to yield the lowest measurement uncertainty in force realization. However, their capacities cannot be extended indefinitely as they become too large in size and prohibitively expensive. Lever amplification of a deadweight force is an option for higher capacities in force realization. This paper describes a new method (patent pending) for automatic compensation of lever arm distortion in order to keep the amplification ratio constant.
This article describes the design of a measuring facility which can be used to investigate and calibrate so-called "friction coefficient sensors". These measuring facilities are used to measure the prestressing force and the tightening torque, resp. the friction torque of screws. These measurements are aimed at optimizing screw joints. The measuring facility described here is part of a force standard machine (fsm). In addition to the force which this system can realize with a very small measurement uncertainty of 0.002 % ( k = 2) (in the measuring range from 20 kN to 1 MN), it can also...
This paper discusses a novel nanopositioning system which is based on an electromagnetic force compensated (EMC) balance. In addition to the positioning the actuating force can also be measured. This enables the measurement of force displacement curves of springs with a wide variety of spring constants. The measurement range of the spring constants is up to 10 10 N/m with a maximum resolution of about 0.01 N/m. Compared to other principles for measuring the spring constant the introduced method is more sophisticated. Both force as well as the displacement can be measured traceable and...
This paper discusses the traceable determination of mechanical parameters of monolithic binocular shaped dual beam spring elements that are applied as force transducers and load cells in the mass and force metrology. Thereby it mainly deals with the measurement of the specific values creeping, reversibility, reproducibility, zero error and interpolation error which are defined in applicable regulations such as the EN ISO 376 standard or the OIML recommendation R 60. Our determination of those parameters is based on an interferometric deformation measurement of a loaded binocular shaped dual...
Radially symmetric bending beams are widely used in the field of reference force transducers. The performance that can be achieved with the transducers currently available is the result of a long development process. This article shows how new machining tools and modern strain gauge technology helps to achieve a new, even lower measurement uncertainty when radially symmetric bending beams are used.
The strain gauge principle is a resistive principle. If a strain is applied only a very small change of resistance occurs. By a Wheatstone bridge the change of resistance can be transferred into a voltage. However this voltage signal on the output of the bridge is still very small. Therefore it must be gained by sophisticated methods. This paper describes the new strain gauge precision instrument DMP41 with highest resolution and highest stability for the use in calibration tasks with e.g. force, torque, pressure transducers or load cells.
This paper describes the procedures and the tests that have been carried out to characterize and to qualify two specific designs for Dynamic Calibration Devices (DCDs) which are intended to be used in the calibration of dynamic force testing machines in accordance with ISO 4965. The dynamic and static behaviour of these DCD structures were analyzed by Finite Element Method (FEM), followed by preliminary experimental characterization tests. Results of these measurement practices are shown and the proposed design is discussed in regard to their application to the standard’s requirements.
An analysis of the dynamic behaviour of the 250 kN primary shock force calibration device at PTB is presented. Two airborne mass bodies with the force transducer under test are brought to collision, and the generated inertial forces are determined by means of laser vibrometers. Measurements with a heavy transducer revealed modal oscillations which were identified by acceleration sensors. The dynamic system behaviour was analysed with a finite element model. It showed that the elastic coupling between the transducer and the reference mass body causes low-frequency oscillations that have to be...