繰返し引張荷重による網糸の疲労

Abstract

To investigate some fatigue properties of netting twines against repeated loads and also the strength of fatigue limit, the present experiments were carried out making use of the apparatus (Fig. 1) using the materials as shown in Table 1. Various hysteresis loops obtained from above mentioned tests in the initial stage are shown in Fig. 2. There are some differences in the type of loops depending upon the kind of material for the twine. The area within a loop represents the energy loss absorbed in the twine during one cycle of cyclic loading. Saran gives over twice the area of amilan. It seems that the above area tends to decrease with the practice of the repeated cyclic loading for several hours. Even if the repeated maximum loads increase, the decrease of energy loss after n times treatment to the initial stage has the same tendency in both saran and amilan. Among the samples applied, with saran a little difference has been found whilst with amilan evidently (Fig. 3). In view of the relation between plastic deformation and maximum load repeated, the strength of fatigue limit is under 17.5kg with saran and 37.0kg with amilan respectively (Fig. 4). This fact is confirmed with next another treatment, namely, according to the relationship between the values of EN/EO and T in Fig. 5, repeated maximum load not producing fatigue seems to be about 17.9kg with saran and 37.0kg with amilan respectively.