본 연구에서는 이와 같은 과대인장하중의 제하과정중에 발생하는 과대압축소 성역이 과대하중에 의한 피로균열의 진전지연에 미치는 영향을 중심으로 하여, 각 소 성역 치수를 매개변수로 하는 해석적 방법을 통하여 가속지연모델을 제안하고, 이를 2024-T3 Al 합금을 이용한 단일과대하중에 의한 지연시험결과 및 Wheeler 나 Willenb- org 등의 기존의 지연모델과 비교 고찰하고자 한다.
It is well known that the fatigue crack growth retardation following overloads can be estimated reasonably well by the models of Wheeler and Willenborg. These models, however, can not explain the delayed-retardation revealed by every experimental result. This means that they necessarily have some qualitative defects in themselves despite of a fair approximation of quantity. In fact, they did not take into account the effects of the compressive portion of the overload cycle such as the change of reversed plastic zone size. The present study is focused on the acceleration effect in the reversed plastic zone in order to analyze qualitatively delayed-retardation phenomenon following single peak overload on the fatigue crack growth behavior using 2024-T3 aluminum alloy.
