A new application of isodensitometry in the moiré technique

Some years ago, isodensitometry was introduced into the moiré technique in order to improve the sensitivity of this method. The application of the Sabattier effect gives now a new possibility to produce more lines of equal displacement. The obtained experimental data are the additional lines and the moiré fringes of full or half order. This method is applied on a beam under pure bending and a circular ring loaded diametrically. It will be shown in this paper that the calibration of the displacement curves can be accomplished by a calibration bar or by ‘self calibration’ which will be done on the same model to be studied. Further, the photographic process can be influenced in a way that different lines of equal displacement can be produced for a given system of moiré fringes. The additional lines are shifted here by choosing different times of exposure.