The Effect of Overload on Crack Growth Behaviour in Biaxial Fatigue

Department of Civil and Materials Engineering, University of Malaga, C/Dr Ortiz Ramos s/n, 29071, Malaga, Spain

^* Corresponding author: mokhtari@uma.es

Abstract

This paper focus on the study of biaxial fatigue cracks based on a methodology that enables evaluation of the overload effect in fatigue. The methodology is based on the experimental evaluation via full-field technique of digital image correlation of the effective stress intensity factor and the crack opening displacement (COD). The tests were performed on cylindrical specimens made of low carbon steel subjected to tension-tension and a combination of tension and torsion loads. The experimental data was used to compare the crack growth behaviour with an overload cycle under uniaxial and biaxial loading. A hybrid method was also employed to evaluate the value of the Stress Intensity Factor (SIF) before and after applying the overload. The results showed a reliable estimation of closure level and SIF for both uniaxial and biaxial loading condition. A new procedure previously developed for uniaxial loads was adapted to the study of biaxial loads. This new procedure was used to identify important differences produced by the overload event.