The extension of the test specimen

The extension of the test specimen is measured from the point of the force/extension curve that corresponds to the pretensioning force as given in 9.3.2. The extension necessary to reach the pretensionshall be added to the gauge length, thus determining the initial length needed for the calculation of the elongation at maximum force.If using electronic devices for recording the extension, ensure that the correct initial length is used for calculation of elongation.9.3.2 Mounted with pretensionApply the appropriate pretension specified as follows:一for all fabrics with stretch characteristics: 0,5 N一for fabrics without stretch characteristics according to mass per unit area: a)‘200 g/m2: 2 N b)>200 g/m2 to 500 g/m2: 5 N c)>500 g/m2: 10 N9.4 OperationClamp a test specimen centrally so that its longitudinal centre-line passes through the centre point of the front edges of the jaws.Engage any device for recording the maximum force and elongation at maximum force. Put the movable clamp in motion and extend the test specimen to the point of rupture. Recorda) the maximum force, and, if required, the force at rupture, in newtons; andb) the extension in millimetres, or the elongation in percent, at maximum force, and, if required, at rupture.Record the extension or the elongation at least to the nearest一0,4 mm or 0,2%for elongations