ポリカーボネートの疲労き裂進展に及ぼす圧縮応力の影響
1988 年 37 巻 418 号 p. 795-800
詳細
1988 年 37 巻 418 号 p. 795-800
In order to clarify the effect of compressive stress on the fatigue crack propagation in polycarbonate, fatigue crack propagation tests with a negative stress ratio and with a single compressive overload were carried out on the pre-cracked specimens. The results obtained in this experiment are summarized as follows:
(1) The compressive stress range in the cyclic loading with a negative stress ratio causes the acceleration in fatigue crack propagation under constant-amplitude loading.
(2) This phenomenon can be explained mainly on the basis of the crack closure concept, but when the negative stress ratio is very high, other factors may also contribute to this phenomenon.
(3) The accelerated crack extension during a tensile overload is not affected appreciably by the negative stress ratio cycling or a single compressive overloading preceding the tensile overload.
(4) The retardation effect due to the tensile overload is not reduced by subsequent negative stress ratio cycling or a single compressive overloading. This fact suggests that the retardation in polycarbonate cannot be attributed to the plasticity-induced crack closure.
