As a reference measurement machine for multi-component force and moment sensors of up to six components, a hexapod-structured calibration device was developed at the Physikalisch-Technische Bundesanstalt in 2001. The machine can generate and measure forces of up to 10 kN and moments of up to 1 kN • m. In this paper, the measurement uncertainty budget of the machine is analyzed, beginning with an improved physical model and calculation of sensitivity coefficients using the implicit function theorem and the Monte Carlo method. The main influencing factors for the measurement uncertainty are discussed and suggestions for further reduction of the uncertainty are given.

A torque-generating measuring device in the 1 MN force standard machine of Physikalisch-Technische Bundesanstalt allows combined load conditions to be generated. Superposition is possible in measuring ranges from 20 kN to 1 MN for axial load and from 20 N • m to 2 kN • m for torque. The measurement facility is unique in the world and offers the opportunity to characterize multi-component sensors specifically with regard to their signal crosstalk. The expanded relative measurement uncertainty (k = 2) of the axial force is 2 • 10 −5 . In the following, the technical details of the torque measuring device and the metrological characterization from the modelling to the measurement uncertainty budget will be described. The model provides an expanded relative measurement uncertainty (k = 2) < 3.9 • 10 −4 . The results of comparison measurements will be discussed.

<p> </p><p><span style="font-family: Calibri;"><span style="font-size: small;">This paper present the completion and the measurement uncertainty budget of a multi-component measuring facility. The new facility is part of the 1 MN force standard machine [1] of the PTB. It enables the simultaneous generation of a torque in the range from 20 N·m to 2 kN·m in addition to axial forces 20 kN to 1 MN. This allows the characterization of measuring systems which require combined loads of axial forces <em>F</em></span>_{<span style="font-size: xx-small;">z</span>}<span style="font-size: small;"> and torques <em>M</em></span>_{<span style="font-size: xx-small;">z</span>}<span style="font-size: small;"> like friction coefficient sensors. The aim is a measurement uncertainty of (<em>k</em> = 2) for <em>M</em></span>_{<span style="font-size: xx-small;">z</span>}<span style="font-size: small;"> &lt; 0.01 % and <em>F</em></span>_{<span style="font-size: xx-small;">z</span>}<span style="font-size: small;"> &lt; 0.002 %. The physical model yields to extended measurement uncertainties (<em>k</em> = 2) for 20 N·m of 5.9·10</span>^{<span style="font-size: xx-small;">-5</span>}<span style="font-size: small;"> and for the maximum load step <span><em>M</em></span>_{<span>z</span>} = (2000 ± 0.084) N·m.</span></span></p><p> </p>

The experimental results, which will be presented in this paper, demonstrate the significant influence of the flow velocity, respectively the rotational speed, on the erosive aggressiveness of cavitating flows. On two of the three investigated test objects, cavitation erosion can only be observed in the initial stage by the so-called pit-count evaluation method. Developed erosion with mass loss is impossible to measure because of the very long duration until mass loss appears. The third test rig generates a very aggressive type of cavitation, so that mass loss, depending on the tested material, will appear after relatively short durations. In addition, the initial stage of cavitation erosion can be observed. Three different techniques were applied to investigate cavitation erosion in the initial and developed stage. Thereby, the capability of methods to quantify erosive effects in dependence of influencing operating parameters has been proven.

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 % (<em>k</em> = 2) (in the measuring range from 20 kN to 1 MN), it can also generate an extremely precise torque (objective: better than 0.005 % at <em>k</em> = 2) in the range from 20 N·m to 2 kN·m.