Papers by Keyword: Systematic Errors

Abstract: The paper discusses the problem of quantifying the contribution of systematic errors on the overall measurement uncertainty. We promote the experimental evaluation of uncertainty due to systematic errors. The method is alternative to non-experimental approaches, including the GUM one. The uncertainty due to systematic errors in ADC-based instruments is addressed.We present a general scheme, and use it for the uncertainty due to ADC gain error. The GUM type B uncertainty seems quite poor, compared to the experimental uncertainty.

Abstract: The determination of strain fields based on displacement components obtained via 2D-DIC is subject to several errors that originate from various sources. In this contribution, we study the impact of a non-perpendicular camera alignment to a planar sheet metal specimen’s surface subject to biaxial loading conditions. The errors are estimated in a numerical experiment. To this purpose, deformed images - that were obtained by imposing finite element (FE) displacement fields on an undeformed image - are numerically rotated for various Euler angles. It is shown that a 3D-DIC stereo configuration induces a substantial compensation for the introduced image-plane displacement gradients. However, higher strain accuracy and precision are obtained - up to the level of a perfect perpendicular alignment - in a proposed ”rectified” 2D-DIC setup. This compensating technique gains benefit from both 2D-DIC (single camera view, basic amount of correlation runs, no cross-camera matching nor triangulation) and 3D-DIC (oblique angle compensation).

Abstract: Reproducibility of diffraction experiments provides an indication of data consistency with respect to different variables. The level of reproducibility and accuracy of the diffraction measurements is increased when using calibrated instruments. The paper presents most significant results of the 'Calibration Monitoring of Diffractometers', a project using a systematic approach to the Round Robin tests. At the present stage, the results suggest that instrumental performances and other related experimental effects in a diffraction the experiment can be summarised through 'characteristic curves'.