Premium
A STUDY OF RESIDUAL CAUSTICS GENERATED FROM FATIGUE CRACKS
Author(s) -
Tomlinson R. A.,
Patterson E. A.
Publication year - 1997
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.1460-2695.1997.tb01503.x
Subject(s) - caustic (mathematics) , residual stress , stress intensity factor , materials science , residual , intensity (physics) , tension (geology) , crack closure , composite material , structural engineering , mechanics , plasticity , fracture mechanics , optics , geometry , mathematics , ultimate tensile strength , physics , engineering , algorithm
— The method of caustics was used to determine the stress intensity factor of fatigue cracks in steel compact tension specimens. Under zero load a residual caustic was observed at the tip of a fatigue crack indicating the presence of a residual stress field. Caustics were generated at increasing static loads and the stress intensity factors were compared with those predicted by theory. It was found that the difference between each measured stress intensity factor and its corresponding theoretical value was a constant for the range of loads. This difference was shown statistically to be equal to the stress intensity factor determined from the residual caustic. The proposed mechanism for the formation of this residual caustic was probably due to crack tip plasticity effects and not due to crack closure. It was concluded that residual caustics can be measured to quantify crack tip behaviour in fatigue cracks and have been shown to be a useful tool in the measurement of residual stress fields.