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Neutron diffraction measurements of residual stresses around a crack tip developed under variable‐amplitude fatigue loadings
Author(s) -
LEE S. Y.,
ROGGE R. B.,
CHOO H.,
LIAW P. K.
Publication year - 2010
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.1460-2695.2010.01490.x
Subject(s) - residual stress , materials science , crack closure , amplitude , neutron diffraction , structural engineering , scanning electron microscope , diffraction , crack tip opening displacement , composite material , tension (geology) , residual , compact tension specimen , fracture mechanics , stress concentration , stress intensity factor , transverse plane , crack growth resistance curve , optics , ultimate tensile strength , mathematics , physics , engineering , algorithm
The spatially resolved neutron‐diffraction residual stress mappings were performed on five compact‐tension (CT) specimens subjected to various variable‐amplitude fatigue loadings (e.g. overload, underload and their mixed loads) during fatigue crack propagation. Three principal residual‐stress components (i.e. longitudinal, transverse and normal stresses) were measured as a function of the distance from the crack tip along the crack‐propagation direction. The shape of respective crack tips on the five CT specimens was examined using scanning electron microscope. The results show the distinct residual‐stress fields near the crack tip and significant changes in the crack‐tip geometry for five different loading cases. It is thought that the combined effects of the changes in the residual‐stress state and crack‐tip geometry seem to be a key factor to account for the observed transient crack‐growth phenomena.