A Reversed η Approach to Estimate Load-Deformation Curves for Fracture Specimens and Surface-Cracked Pipes

Abstract This paper presents a reversed η approach to estimate the load-deformation curve for fracture specimens subjected to monotonic and reversed loadings based on the measured J-R curve and extends the same procedure to surface-cracked pipes under monotonic actions. The proposed method predicates on the original η approach to uncouple the load-deformation data from the potential energy at different crack sizes, through a load separation method. This approach estimates closely the load-deformation curve for SE(B), C(T) and clamped SE(T) specimens under monotonic loadings. Besides, the proposed procedure predicts closely the envelope of the load-deformation curve for C(T) and SE(T) specimens under low-cycle actions. For pipes with a circumferential surface crack, the reversed η approach also leads to a reasonably accurate estimation of the load-deformation response. The proposed method provides a basic approach to estimate the fracture dependent load-deformation curve for large scale structural components, which allows upscaling of the material fracture resistance into the load-deformation characteristics required in the integrity assessment of large-scale engineering structures.