On Determination of Parameters of the Unified Fatigue Crack Growth Rate Model from Tensile Test Data

摘要

Marine structures such as ships and offshore platforms are mostly made of metals and designed with damage tolerance. This design philosophy requires accurate prediction of fatigue crack growth under service conditions. Now more and more people have realized that only a fatigue life prediction method based on fatigue crack propagation (FCP) theory has the potential to explain various fatigue phenomena observed. In the past seven years, the authors' group have developed a unified fatigue crack growth rate expression which has the capability to explain various observed fatigue phenomena. However, this expression involves many model parameters and if all of them are determined by fatigue propagation tests, many tests have to be carried out which are both time consuming and cost expensive. In this paper, the method to determine the model parameters from tensile test data is discussed and it is shown that the crack growth rate of an acceptable accuracy can be derived from only tensile test data.