Fatigue crack propagation in HSLA steel specimens subjected to unordered and ordered load spectra

Prediction of fatigue crack propagation in metallic structures subjected to dynamic random load spectra, containing variable overloads and underloads, is challenging because of possible retardation and acceleration effects. In this paper, fatigue crack growth behaviour under random spectrum load is investigated on ESE(T) specimens made of DNV 460 steel, which is an HSLA steel widely used in the offshore industry. A reference spectrum composed of a sequence of random loads is transferred into various reduced and ordered spectra. Reduced spectra have been defined based on a peak-valley segmentation algorithm and on the deletion of non-damaging events. Ordered spectra consist of block loading sequences determined by rainflow counting methods. Specific control software has been developed that allows to execute the K (stress intensity factor) controlled experimental program and perform on-line crack growth measurement using a material compliance method. The different spectra are compared in terms of total crack extension and retardation in crack growth rate. Algorithms for crack growth simulation have been implemented in Abaqus using both existing and adapted plastic zone models. Numerical results are critically compared to the experimental data.

ISBN:9789811383311

Publication year:2019

Accessibility:Closed