Abstract:
The load interaction effects that occur under variable amplitude loading conditions following single peak overloads, low-high blocks and high-low blocks have been investigated on a commonly used structural steel. A detailed investigation has been carried out on long cracks which aims at developing and assessing the efficacy of a simple predictive model based on closure and plastic zone effects.
The material was tested in a quenched and tempered condition. All the tests were carried out in the four point bending mode, in both the Paris regime and near the threshold, with overloads ranging from 10% to 100%.
An attempt to relate crack closure to crack growth rates in the transient growth rate region (which follows a load change) was made.
The trends observed for a wide range of loading parameters are presented.
