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EVALUATION OF FATIGUE CRACK PROPAGATION PROPERTIES UNDER RANDOM LOADING AVOIDING CRACK CLOSURE
Author(s) -
Suzuki Naoyuki,
Takeda Harumasa,
Ohta Akihiko,
Ohuchida Hisasi
Publication year - 1991
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.1460-2695.1991.tb00713.x
Subject(s) - crack closure , materials science , structural engineering , amplitude , rayleigh distribution , fracture mechanics , closure (psychology) , vibration fatigue , composite material , rayleigh scattering , fatigue testing , engineering , physics , market economy , optics , quantum mechanics , economics
— Fatigue crack propagation rates and the fatigue threshold of HT80 steel were measured by maintaining the maximum load during the whole period of random loading in order to prevent fatigue crack closure. The random loading pattern involved 62 level block loadings in which the waveform was approximated to the Rayleigh distribution of peaks. The fatigue crack propagation rates under random loading were well predicted from those obtained from constant amplitude loading and assuming a linear cumulative damage law. That is, da/dn = C {Δ K m eq −Δ K m th } where the equivalent stress intensity factor, Δ K eq ={= n i Δ K m i /d n i } 1/ m , where n i = 0 for Δ K i ≤Δ K th , or n i = n i for Δ K i > Δ K th .