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RESIDUAL STRESS FIELDS DURING FATIGUE CRACK GROWTH
Author(s) -
Sun Wei,
Sehitoglu Huseyin
Publication year - 1992
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1992.tb00042.x
Subject(s) - crack closure , materials science , residual stress , paris' law , crack growth resistance curve , crack tip opening displacement , plasticity , structural engineering , plane stress , composite material , stress concentration , stress intensity factor , deformation (meteorology) , stress (linguistics) , ultimate tensile strength , fracture mechanics , finite element method , engineering , linguistics , philosophy
This study outlines the distinction between (1) residual stresses at an ideal crack tip, undergoing reversed deformation in the absence of crack closure, and (2) additional residual stresses generated due to plasticity induced closure upon fatigue crack growth. Residual stresses resulting from reversed deformation in plane strain were higher compared to the plane stress case, while residual stresses generated behind the crack tip were more significant in plane stress compared to plane strain. The origin of these residual stresses was studied for two specimen geometries over a wide range of loading conditions. We define a new crack tip parameter, S tt as the applied stress level that corresponds to the development of tensile stresses immediately ahead of crack tips. The S tt levels were significantly higher for a fatigue crack than for an ideal crack. We attribute the difference in S tt levels between these two cases to plasticity induced closure. The results demonstrate the importance of the S tt parameter, since the stresses ahead of crack tips could remain compressive even when the crack surfaces are open. Moreover, the study emphasizes the need, when describing fatigue crack growth, to incorporate both the closure concept and residual stress field ahead of a crack tip.