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Torsion response of a cracked stainless steel shaft
Author(s) -
LISSENDEN C. J.,
TISSOT S. P.,
TRETHEWEY M. W.,
MAYNARD K. P.
Publication year - 2007
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.1460-2695.2007.01149.x
Subject(s) - torsion (gastropod) , structural engineering , quasistatic process , stiffness , finite element method , torsional vibration , materials science , vibration , cracking , crack tip opening displacement , crack closure , natural frequency , engineering , fracture mechanics , composite material , physics , medicine , surgery , quantum mechanics
Pump shafts used for power generation are susceptible to fatigue cracking while often in near‐continuous operation. Technology based on torsional vibration is under development for condition‐based assessment of shaft health. The focus of this paper is on the relationship between a crack, which propagated due to bending loads, and the torsional stiffness of the shaft. An analytical method to determine the compliance associated with a crack has been implemented for a semi‐elliptical surface crack. A 3‐D finite element model of a shaft section with a crack has also been used to predict the effect of a crack on stiffness. Fatigue cracks were seeded in shafts on a three‐point bend apparatus. A benchtop test rig was constructed to evaluate the torsional natural frequencies of a cracked shaft system. Quasistatic torsional stiffness tests indicated that crack closure has an effect on the results. A torsional finite element model of the benchtop test rig indicates that the first torsional natural frequency is reduced by the propagation of a crack. The reduction in torsional stiffness of the shaft inferred from the natural frequency results is in reasonable agreement with the quasistatic results and the model predictions.