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FATIGUE LIFE PREDICTION IN BENDING FROM AXIAL FATIGUE INFORMATION
Author(s) -
Manson S. S.,
Muralidharan U.
Publication year - 1987
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.1460-2695.1987.tb00462.x
Subject(s) - materials science , bending , stress (linguistics) , structural engineering , hardening (computing) , pure bending , flow stress , strain hardening exponent , goodman relation , plasticity , composite material , mechanics , stress concentration , fracture mechanics , physics , engineering , strain rate , philosophy , linguistics , layer (electronics)
Bending fatigue in the low cyclic life range differs from axial fatigue due to the plastic flow which alters the linear stress‐strain relation normally used to determine the nominal stresses. An approach is presented in this report to take into account the plastic flow in calculating nominal bending stress S bending based on true surface stress. For a given surface strain ε S , hence the surface life ( N S ), an equation is derived to express S bending in terms of axial fatigue stress ( S axial ), involving material constants c, b, N T which are obtained from axial fatigue information and f 1 and f 2 which are functions of strain hardening exponent and depend on the geometry of cross‐section. These functions are derived in closed form for rectangular and circular cross‐sections. The nominal bending stress and the axial fatigue stress are plotted as a function of life ( N S ) and these curves are shown for some materials of engineering interest.