BS EN 4861:2020 pdf free.Aerospace series – Metrological assessment procedure for kinematic fields measured by digital image correlation.
BS EN 4861 This document specifies the monitoring of mechanical tests and inspections performed both at the material (coupon) and at the structural scale by the implementation of kinematic field measurements by digital image correlation. This document describes an in situ method for evaluating the metrological performance of an extensometer system using image correlation for the delivery of displacement fields, and by extrapolation, of deformation fields. It can be implemented prior to the actual start of the test [or inspection). It will inform of the metrological performance in testing conditions.  This document allows the metrological performance of the measuring technology to be quantified.  The methodology described herein is not to be considered as a calibration step. This reference document does not exhaustively specify the constitutive elements of a generic system of Digital Ilmage Correlation measurement. This reference does not address the measurement of 3D shapes via stereocorrelation systems.The system for the assessment of the metrological performance, which allows a known displacement lt to be applied with respect to the object of interest, may consist of a rigid frame to which the image acquisition device is attached. The system for the assessment of the metrological performance shall comprise a mechanism for moving along the 3 (three) axes in space by translation, optionally from 1 Cone) to 3 (three) rotations and a measuring device allowing to allow these displacements to be known accurately. These variations in length can be measured by, for example, by an interferometer, a linear incremental encoder or gauge blocks and a comparator, or a micrometre.The calibration apparatus and the supporting equipment (such as micrometres, callipers, and optical projection microscopes) shall be calibrated using standards that are traceable to the International System of Units (SI).  The uncertainty associated with any measurement made by the supporting equipment shall not exceed  one third of the allowable error of the extensometer system being calibrated, see Table 2.The temperature measurement instrument shall have a resolution of 0,1 °C. BS EN 4861 pdf download.