ISO 5629:2017 pdf free

ISO 5629:2017 pdf free.Paper and board一Determination of bending stiffness一Resonance method
Set the clamp into vibration and carefully pull the test piece through the clamp until the free end of the test piece goes into resonance. This point is characterized by maximum amplitude of vibration and maximum sharpness of visibility of the vibrating end of the test piece under stroboscopic ilumination (5.4).
Check that the edge of the test piece is still perpendicular to the edge of the clamp.
Measure, as accurately as possible, the length of test piece projecting past the edge of the clamp.
This may be done by carefully cutting or marking the test piece at the clamp edge, removing it from the clamps and measuring its length using a steel rule or other suitable device. The accuracy of measurement of resonant length shall be within ±0,25 mm or ±0,5 %, whichever value is greater in the particular instance concerned.
Alternatively, if the instrument is fitted with a lower clamp coupled to a measuring scale, this may be used. If this is done, the measurement should be carried out in accordance with the manufacturer’s instructions, but it is essential that it should be checked that the test piece has not stretched significantly during the test and thus, that the length indicated by the scale is identical with the length of test piece protruding past the clamp.
Check if necessary, by further decreasing the projecting length, that the resonance point has been reached and that resonance is occurring with only one antinode, since it is possible to obtain resonance showing two antinodes and one node (see Figure 2).
For materials of very low grammage, it may be necessary to release the clamping pressure while adjusting the projecting length to give resonance. For materials of higher grammage, it may be possible to make the final adjustment of the projecting length to obtain resonance by both pulling and pushing the test piece through the clamp. However, the clamping pressure should be applied while the state of resonance is checked.ISO 5629 pdf download.