FCP Report No. 9

Cyclic Stress-Strain Behavior and Fatigue Resistance of Two Structural Steels


J. F. Martin
Department of Theoretical and Applied Mechanics


The stress-strain behavior and fatigue resistance of two structural steels are investigated. Specimens were cut from thin steel sheets and cylindrical steel bars. The thin sheet specimens were designed so as to prevent buckling. Total axial strain for these sheet specimens was computed from the transverse strain and load by an analytical expression programmed through an analog computer. The monotonic and stable cyclic stress-strain properties for both steels are similar. Cycle dependent hardening and softening were not as evident for the sheet steel. Three different procedures for determining the stable cyclic behavior produced considerably different results. Strain-life data showed the effects of a single initial overstrain and periodic overstrains. Both types of overstraining of the bar steel produced similar fatigue data to that of the non-overstrained and initially overstrained sheet steel results.

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