Volume 34, Issue 5 (September 2006)
The Influence of Initial Crack Length on Critical Stress Intensity Factor K1
It is postulated that initial crack length always affects the critical propagation of a crack, except when absolutely elastic materials are considered. The reason for this statement is explained, and a new fracture mechanics theory is presented and experimentally justified, complementing previous works in which it was partially developed.
The main innovation presented in this paper is a new fracture mechanics method, called “Limit Line Replacement,” which is thought to be applicable to any type of structure, provided some experimental verification is made.
This basis of the method consists in the acceptance that the critical crack length of a cracked structure subjected to fatigue always can be obtained experimentally, if the maximum and the minimum fatigue loads are known.
From this critical crack length, the life of a structure can be estimated experimentally if under similar conditions, the number of required cycles is measured.