Describing fatigue crack growth and load ratio effects in Al 2524 T3 alloy with an enhanced exponential model

The fatigue crack behavior in metals and alloys under constant amplitude test conditions is usually described by relationships between the crack growth rate da/dN and the stress intensity factor range ΔK. In the present work, an enhanced two-parameter exponential equation of fatigue crack growth was introduced in order to describe sub-critical crack propagation behavior of Al 2524-T3 alloy, commonly used in aircraft engineering applications. It was demonstrated that besides adequately correlating the load ratio effects, the exponential model also accounts for the slight deviations from linearity shown by the experimental curves. A comparison with Elber, Kujawski and “Unified Approach” models allowed for verifying the better performance, when confronted to the other tested models, presented by the exponential model.

► Fatigue crack growth data for 6 load ratios in Al 2524 T3 alloy were obtained.
► An enhanced two-parameter exponential equation of FCG was proposed.
► The exponential model’s performance was compared to conventional FCG models.
► The exponential model was able to adequately describe the R-effects for Al 2524 T3.
► Deviations from linearity shown by the experimental points were also accounted for.