... behaviors of fatigue cracks in the plane stress and in the plane strain regions. Crack closure, the blunting, and the retardation after an overload depend on the position along the front. ultrasound diffraction crack tip crack size measurement fatigue test specimens crack closure curved crack...

... cycles between overloads, even though all minor cycles are below the threshold stress intensity. acceleration acoustic emission (AE) crack growth fatigue damage lifetime prediction load interaction overload retardation threshold Zhendong Zhou ~and Farrel J. Zwerneman 2 Fatigue Damage Due...

... gage and through transmission ultrasonics. Crack growth rate results show that closely spaced overloads can cause acceleration; retardation occurs only if overloads are separated by many small cycles. Comparison of crack opening data to crack opening estimates based on Elber's closure model shows...

..., where engineered barriers are in place to limit access of water and to retard the migration of radionuclides into the biosphere. A test program underway at Chalk River, Ontario is attempting to provide an understanding of the release and transport of radionuclides under more realistic conditions...

... propagation crack closure plastic deformation plastic zone cyclic loads stress analysis retardation fatigue life predictions crack opening model crack growth model Arij U. de Koning^ and Gert Liefting^ Analysis of Crack Opening Behavior by Application of a Discretized Strip Yield Model REFERENCE...

... range can be rationally derived and used to account for the fatigue crack threshold, certain small crack behavior, and retardation. fatigue crack growth similitude plastic strain range crack growth analysis retardation threshold small cracks David Broek A Similitude Criterion for Fatigue...

... The effect of low-temperature toughness degradation on damage tolerance and life analysis methodology is discussed. Spectrum fatigue and fatigue crack growth tests were conducted and life predictions made on 7475-T761 aluminum. The retardation behavior was determined by conducting constant K...

... In predicting crack growth behavior under arbitrary spectrum loads, one must consider the effects of tensile and compressive overloads to retard and accelerate growth. There are two major categories of crack growth models for prediction of retardation and acceleration behavior: yield zone models...

... microstructural effects on transient (that is, spectrum) FCG behavior are contrasted with those for steady-state (constant load amplitude) fatigue performance. fracture mechanics metal fatigue crack propagation microstructure retardation variable amplitude spectrum loading aluminum alloy p. E...

... growth behavior in a corrosive environment for spectrum loading. corrosion fatigue crack growth enhancement crack propagation (growth) environment fracture mechanics hydrogen embrittlement Paris' region retardation spectrum loading superposition model sustained load crack growth Y. H...

... experimental data. Finally, the qualitative changes in the form of standard S-N curves for welded details are predicted, and shown to conform with limited available S-N curve experimental data. crack growth crack propagation cylinders fracture (materials) residual stress retardation stress...

... yielding resulted in residual stresses that maximized crack growth retardation. As a result, an increase in fatigue life was produced by periodically inserting the proof load into the operating load spectrum. The primary impact of this program was to demonstrate that the proof test interval for the hook...

... A series of experiments were performed in an attempt to investigate the effect of creep strain and temperature on the fatigue life of a [±45] 2s graphite/epoxy composite laminate. The experimental results indicate that sustained periods of static loads have significant retardation effects...

... from two different approaches. One approach did not account for the load interaction effects to the fatigue crack growth, while the other approach considered both the tensile overload retardation and the compressive load acceleration effects as well as the reduction of overload retardation effect...

.... The influence of specimen thickness is considered for both the isolated event and the spectrum loading experiments. fatigue crack growth fatigue (materials) spectrum loading elevated temperature retardation load interactions sustained loading nickel-base superalloy life predictions cumulative...

... An engineering model has been developed to assess the impact of load spectrum variables on fatigue crack growth in metal structures. The model is based on the effective stress concept of Willenborg et al and Gallagher et al, and has been extended to accommodate retardation/acceleration phenomena...

... Yield Point to 4 in. Thick (Grade A) (A 588), has shown that the crack-growth rates ( da/dN ) in the welds were similar to or up to five times slower than the rate in the base steels. The retardation in crack-growth rate was observed to be substantially greater for crack propagation in the coarse...

... The 2024-T8, 7075-T6, and 7075-T73 alloys were studied in laboratory air and 3.5 percent sodium chloride (NaCl) solution to investigate the effects of a corrosive environment on the retardation behavior of aluminum alloys. Single overload cycles at overload ratios of 1.5, 2.0, and 2.5 were used...

..., −1 and −2. The single overload test program excluded R l = +1/2, and the intermittent overload program was for R l = 0 only. A new simplified mathematical model was introduced which assumes that fatigue crack growth retardation is primarily a function of the overload ratio and the load ratio...