AIAA Journal · 1974 · 38 citations · 4 references
Natural SciencesMaterials EngineeringMaterials ScienceMechanical Behavior Of MaterialsMetallurgyStructural MaterialsDamage MechanicsFatigueFracture MechanicsStrength Of MaterialsStress-strain BehaviorWork HardeningCrack GrowthCracksFatigue Crack GrowthFatigue Crack PropagationFatigue FractureFatigue LoadsFatigue Under Cyclic LoadingPlastic Zone Analysis
The effect of single peak overloads on fatigue crack growth was investigated using center crack sheet specimens of 2024-T3 aluminum alloy. The magnitudes of the overload stress intensity values were selected to provide ratios of the overload plastic zone size to the fatigue plastic zone size (r0/r/max = #*) equal to 5, 10, 15, and 20. To provide a constant fatigue plastic zone size, quasi-constant stress intensity tests were run by means of a load shedding technique. The delaying effect due to a single peak overload was found to increase as the value of R* and consequently as r0, increased. The higher values of R* were large enough to produce an overload plastic zone that would result nonpropagating fatigue cracks after 1.5 x 10 cycles. A zeroing in technique was used to determine the size of the plastic zone required to arrest a crack at any particular fatigue stress intensity level. From the experimental data, a relationship was developed for approximating the amount of fatigue crack delay incurred due to overloading.
4