Measurement of deformation using markers enables most accurate results also with difficult measuring and environmental conditions. The high accuracy of the measuring systems up to class 0.2 is also a result of good marking. The figures below show the requirements of a good marking.
Markers have to be parallel to each other
Markers have to be aligned perpendicular to the centre line (loading direction)
Markers should be have sharp edges, similar to foil cutted by a scalpell
Markers have to stick also at large strains and should be following the deformation of the specimen as required |