Structural Behavior after Fatigue.
BATTELLE COLUMBUS DIV OH
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This study examines the extent to which prior cyclic history, which causes a change in mechanical properties through cyclic softening, influences the fatigue crack propagation FCP and fracture toughness behavior of steel specimens. The effect of predamage was determined empirically by comparing fracture toughness and FCP behavior developed for virgin materials with that found for predamaged materials. The scope of the study included testing under ambient conditions as well as in seawater at frequencies as low as 0.2 Hz. The main conclusion of the study was that apparent predamage effects are due to the influence of cyclic softening on the test methods and related data interpretation. When J sub Ic is used as the basis to assess fracture toughness, the difference between virgin and predamaged toughnesses was negligible. Likewise, fatigue crack growth rates were similiar. For virgin and predamaged materials provided that crack closure was accounted for by using the range of the effective stress intensity factor to correlate growth rates.
- Properties of Metals and Alloys