Evaluating fatigue crack propagation properties using a cylindrical rod specimen

Shin, C.S.; Cai, Chen

doi:10.1016/j.ijfatigue.2006.06.006

Cited by 18 publications

(6 citation statements)

References 26 publications

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“…As the crack propagates through a round specimen bar, the crack shape factor β increases, mainly because the ligament area reduces. The round bar crack through stress intensity factor problem has been widely investigated, even recently, through Finite Element (FE) [39][40][41][42][43]24]. In these papers particular attention was devoted to the crack shape evolution, when the crack propagates inside the round bar, for different initial elliptical crack aspect ratios.…”

Section: Fatigue Crack Initiation From S-n Curvesmentioning

confidence: 99%

Physically short crack propagation in metals during high cycle fatigue

Santus

Taylor

2009

International Journal of Fatigue

124

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In metals, during high cycle fatigue on plain specimens, almost the entire fatigue life is spent as short crack initiation and propagation. The fatigue short crack life can be schematically divided into two subsequent phases: microstructurally short crack and physically short crack. Recently, Chapetti proposed a physically short crack threshold and propagation driving force model [1]. In his model the physically short crack behavior is obtained from the long crack propagation, just introducing the reduced threshold due to unsaturated closure. In the present paper the physically short crack propagation is similarly modeled by means of a driving force equation, but independent from the long crack propagation. In this way, a better description of the short crack behavior is provided, however short crack propagation data is required. Physically short crack propagation model parameters were obtained, by fitting experimental data drawn from the literature, for two Aluminum alloys and a Titanium alloy at two different heat treatment conditions and load ratios. By calculating the physically short crack plus long crack propagation, and assuming microstructurally short crack as part of the initiation stage, a purer information about crack initiation can be drawn from the S − N curves, and it is shown in the paper for the investigated materials. A precise crack initiation size and the number of cycles just for initiation are then provided. This information is useful to accurately predict fatigue life for blunt notched and for thick components, where the propagation is much higher than in the small plain specimen. A validation of the model was obtained by predicting the fatigue life of a notched specimen. An accurate prediction was obtained both when the initiation was much smaller than propagation and when almost the entire fatigue life was initiation.

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Section: Fatigue Crack Initiation From S-n Curvesmentioning

confidence: 99%

Physically short crack propagation in metals during high cycle fatigue

Santus

Taylor

2009

International Journal of Fatigue

124

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“…This region is commonly believed to account for a significant proportion of the fatigue life of a component. Region II fatigue-crack growth (FCG) corresponds to stable macroscopic crack growth and has been extensively studied for its technological importance [16][17][18]. This region, normally known as the Paris region, shows essentially a linear relationship between log da/dN and log K and the Paris equation can be used to model the crack propagation in this region.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical study to predict crack growth in a thick-walled cylinder under fatigue loading

Malik

Salam

Abid

2008

Proceedings of the Institution of Mechanical Engineers, Part E:

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Experimental and numerical studies were carried out to predict the crack growth rate under fatigue loading in a thick-walled cylinder made of aluminum alloy. Extensive experimental fatigue-crack growth data on middle tension samples was compiled and applied to simulate and predict the crack growth process using detailed two-dimensional parametric finite-element (FE) technique. The fatigue-crack propagation was simulated, based on linear elastic fracture mechanics and stress intensity factor determination. The FE model provided results of crackgrowth analysis optimized for stress levels ranging from 40 per cent to 25 per cent of the material yield stress. Fatigue-life analysis of the samples showed that the results obtained from the two techniques were in good agreement up to a stress range of 79 MPa. However, at lower stress ranges, the number of cycles to failure as determined by FE analysis (FEA) was smaller than found experimentally. The experimental results were 13 per cent and 36 per cent higher than FEA results at stress ranges of 63 and 49 MPa, respectively. This disparity was explained in terms of the crack growth rates near the threshold stress intensity factor range.

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“…The fatigue crack propagation rate ð da dN Þ versus the stress intensity range (DK) data derived from five rod specimens [17] and m e = 3.081, which were obtained from the best fit to the experimental growth rate data correlated in terms of DK eff [17].…”

Section: Baseline Fatigue Crack Propagation Datamentioning

confidence: 99%