Fatigue Behavior of Gray Cast Iron under Axial and Bending Loads
by
Peter J. Furman
Materials and Design Division
Departments of Mechanical and Industrial Engineering
Abstract
Recent developments in characterizing low cycle (<105) fatigue behavior of gray cast iron were extended by investigating the effects of compressive mean stress. Axial fatigue tests were conducted with either tensile or compressive maximum stresses. A Manson-Halford formulation of the strain-life approach was found to be less effective for low cycle fatigue life prediction than a Smith, Watson, and Topper (SWT) combined stress-strain damage parameter. Fatigue lives from a wide range of axial loading conditions demonstrate good correlation using the SWT parameter.
Flexural fatigue behavior of gray cast iron was also investigated. Strain energy concepts were employed to predict stress-strain response of a beam under four-point bending. Fatigue lives were estimated from stress-strain predictions at the location of maximum stress. Strain gauge results from the bending tests indicated that strain energy concepts accurately predicted the beam deformation. Fatigue lives were accurately predicted by employing the damage parameter identified for axial loading.
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