Fatigue crack growth characteristics of single-sided surface cracks in GLARE: Effects of loading condition and laminate configuration

Abstract

GLARE have garnered extensive application and research interest across engineering domains owing to their exceptional mechanical properties. However, in service, surface and single-sided surface cracks often initiate due to scratches from sharp objects, posing notable threats to structural integrity. Digital image correlation was employed to in-situ monitor and quantify crack length evolution and laminate strain fields during fatigue loading. Systematic investigations evaluated the effect of initial crack depth on single-sided surface cracks propagation, influences of structural configurations and loading conditions on fatigue growth and associated delamination, and propagation differences between single-sided surface and through cracks. Our findings reveal four key insights: initial crack depth dictates the onset of single-sided surface cracks propagation but not subsequent growth kinetics; their fatigue growth rate trends are fundamentally distinct from through cracks; single-sided surface cracks growth rates exhibit lower sensitivity to stress ratio variations; and increasing the laminate count yields less significant improvement in fatigue resistance for single-sided surface cracks. This work elucidates the unique fatigue propagation mechanisms of single-sided surface cracks in GLARE, filling a critical knowledge gap. The findings provide foundational data and mechanistic insights to advance accurate predictive models for structural integrity assessment of GLARE components, supporting their reliable engineering application.