The repeated-impulse testing like the drop testing was discussed in these studies.
The principle of the repeated-impulse testing was that a weight was dropped from a constant height and the energy of it was given the tested paper repeatedly.
The relation between the repeated-impulse testing and the mechanical properties of paper was also discussed.
The materials tested in these studies were kraft paper and high stretchable paper.
The results were as follows.
(1) The machine direction of kraft paper was brittle, but it was not fatigued soon or immediately.
(2) The toughness of virgin paper was related to the results of the repeated-impulse testing in most cases.
(3) However, for evaluation of the service strength of bag paper, it was not sufficient that only the toughnes was measured.
It should be necessary that the decrease rate of toughness during the repeated-impulse testing must he measured additionally.