木材の引張クリープにおける破壊時間依存性

その他

The fluctuation phenomena were mvestigated experimentally on the tensile creep fracture in Sugi wood(Cryptomeria japonica D. DON.)
The size and shape of our specimens and experimental apparatus were shown in Fig. 1 and Photo. 1 respectively. The tensile creep test of about 90 specimens were measure by three constant load (222.8g/<mm>^2, 201.4g/<mm>^2 and 185.0g/<mm>^2). Experimental temperature were 20 ± 1 ℃.
From the standpoint of stochastic process, the probability of occurrence of fracture in unit time after the lapse of time t, m(t), are given by tangent of log P-t diagram, when P(t) is probability of occurrence in the limited case of our creep test. and (4). Fig. 2 shows log P-t diagram in the limited case of our creep test.
The elapsed time until fracture occurres under constant load were measured by a stop-watch and electrical-clock. Our experimental results in tensile strength and creep test are shown in Table 1 and 2 , respectively. As the resuls of analysis of variance, it became clear that fluctuations of fracture time in creep are not attributed to the fluctuations of annual ring breadth between each specimen. From the result in Fig. 2, we may say that the value of m under the constant load decreases rapidly in the beginning of loading and approaches to an almost constant value.