An experimental study of loading parameters effect on fatigue crack closure in 12NC6 steel

In this paper, the fatigue crack closure (FCC) phenomenon was experimentally revealed using the back face strain gauges technique. The effects of the loading parameters on FCC have been investigated on 12NC6 heat treated steel. Four yield stresses values have been tested. The loading conditions were chosen to have the stress intensity factor range ΔK between 17 and 30 MPaView the MathML sourcem with four load ratio values: 0.05-0.1-0.3 and 0.5. In this study, the closure stress intensity factor Kcl is approximately constant for all load ratio values (R). The expression describing the evolution of the closure parameter U is obtained as a function of both the R and Kmax.