It has been well-established that the non-singular T-stress provides a first-order estimate of geometry and loading mode (e.g. tension versus bending) effects on elastic–plastic crack-front field under mode I loading conditions. The objective of this paper is to exam the T-stress effect on three-dimensional (3D) crack-front fields under mixed-mode (modes I and II) loading. To this end, detailed 3D small strain, elastic–plastic simulations are carried out using a 3D boundary layer (small-scale yielding) formulation. Characteristics of near crack-front fields are investigated for a wide range of T-stresses (T/σ0 = −0.8, −0.4, 0.0, 0.4, 0.8). The plastic zones and thickness and angular and radial variations of the stresses are studied, corresponding to two values of the remote elastic mixity parameters Me = 0.3 and 0.7, under both low and high levels of applied loads. It is found that different T-stresses have a significant effect on the plastic zones size and shapes, regardless of the mode mixity and load level. The thickness, angular and radial distributions of stresses are also affected markedly by T-stress. It is important to include these effects when investigating the mixed-mode ductile fracture failure process in thin-walled structural components.

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Keywords constraint effect, crack-front fields, elastic–plastic fracture, mixed-mode loading, T-stress, three-dimensional effects
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Journal Fatigue and Fracture of Engineering Materials and Structures
Ding, P., & Wang, X. (2017). Three-dimensional mixed-mode (I and II) crack-front fields in ductile thin plates — effects of T-stress. Fatigue and Fracture of Engineering Materials and Structures, 40(3), 349–363. doi:10.1111/ffe.12498