Definition of damage parameter in low-cycle fatigue of gray cast iron

Gray cast iron shows large asymmetrical features by the graphite flake when tensile and compressive stresses are applied. The plastic strain rage which is used in low-cycle fatigue life prediction by many researchers is hardly defined and gives very different values by the Standards in this case. From the results of this study, it is not reliable to use the plastic strain range as a low-cycle fatigue damage parameter. Therefore, the plastic strain energy density which is uniquely defined was suggested as a damage parameter and it showed good correlation in low-cycle fatigue in gray cast iron.