Low Cycle Torsional Fatigue of 1045 Steel in Shear Strain Control
by
Gail E. Leese
Department of Theoretical and Applied Mechanics
Abstract
An experimental technique is established for performing strain controlled fatigue tests in torsion on thin-walled tubular specimens. The results of such tests on a 1045 hot rolled and normalized steel are reported. Fatigue crack initiation properties are determined in a manner analagous to the method used with axial fatigue data reduction.
Mode II (inplane shear) surface cracks are observed throughout a significant portion of the life of the 1045 specimens. Often, many cracks are observed that have no apparent effect on the final failure. This phenomenon is documented with surface replication techniques.
Finally, for the steel tested, it is established that the fatigue strength exponent, fatigue ductility exponent and cyclic strain hardening exponent are essentially the same in torsional and axial loading modes.
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