The effect of crystal orientations on fatigue crack growth

1968 ◽  
Vol 46 (19) ◽  
pp. 2225-2226 ◽  
Author(s):  
R. W. Lardner
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Plastic Zone ◽  
Crack Growth ◽  
Average Rate ◽  
Previous Theory ◽  
Line Material ◽  
Dislocation Arrays ◽  
Mode 2 ◽  
Slip Planes

A previous theory of fatigue crack growth in metals was based on an analysis of the plastic zone at the tip of a crack in terms of coplanar dislocation arrays. This analysis has been extended to the case of oblique slip planes. It is shown that, for the case of a crack growing in mode 2 through a polycrystal-line material, the average rate of growth through the differing orientations of many grains is almost identical with that obtained by the coplanar analysis.

Fatigue crack growth and the plastic zone in air and in vacuum

1981 ◽  
Vol 13 (4) ◽  
pp. 420-425
Author(s):  
N. M. Grinberg ◽  
A. M. Gavrilyako ◽  
N. L. D'yakonenko ◽  
I. L. Ostapenko ◽  
V. A. Serdyuk
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Plastic Zone ◽  
Crack Growth

A Weakest-Link Model for the Prediction of Fatigue Crack Growth Rate

1978 ◽  
Vol 100 (2) ◽  
pp. 170-174 ◽  
Author(s):  
Kong Ping Oh
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Average Rate ◽  
Joint Probability ◽  
Random Variable ◽  
Weakest Link ◽  
Link Theory ◽  
Link Model ◽  
Joint Probability Density

A weakest-link theory is proposed for analyzing the rate of fatigue crack growth. The joint probability density of a fatigue crack growing an amount X between x and x+dx, and in time η between N and N+dN cycles is derived from an initial probability function. The rate of crack growth is then obtained as the expectation of the random variable (X/η). It is shown that the average rate of crack growth obeys the power law for small ΔK, and that the power is a function of the shape parameter in the Weibull distribution.

Fatigue Crack Propagation in Steels for Railway Axles

2013 ◽  
Vol 592-593 ◽  
pp. 254-257
Author(s):  
Luboš Náhlík ◽  
Pavel Pokorný ◽  
Pavel Hutař ◽  
Petr Matušek
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Plastic Zone ◽  
Crack Growth ◽  
Fatigue Cracks ◽  
Know How ◽  
Compressive Stresses ◽  
Railway Axle ◽  
Real Geometry ◽  
Front Shape

The paper deals with the influence of order of cycles in the loading block on the fatigue crack growth rate in railway axle. The railway axle can include some cracks from manufacturing process or initiated fatigue cracks from previous operation. It is advantageous to know how the crack will behave during further service of the train to ensure its safe operation. The most common approaches describing the fatigue crack growth do not take into account the effects of overload cycles, which enlarge the plastic zone ahead of the crack tip. The enlarged plastic zone generates residual compressive stresses, which cause a retardation of the fatigue crack growth. Finite element numerical calculations were used together with the generalized Willenborg model to determine influence of overload cycles on the increment of fatigue crack growing in railway axles. Real geometry of the axle, the crack front shape and typical loading spectrum were taken into account.

A Study on Evaluation of Overload Effects on Fatigue Crack Growth

2004 ◽  
Vol 261-263 ◽  
pp. 1169-1178 ◽  
Author(s):  
Ki Sung Kim ◽  
Kyung Su Kim ◽  
Chun S. Shim ◽  
Hyung M. Cho
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Plastic Zone ◽  
Crack Growth ◽  
Growth Retardation ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry ◽  
Crack Growth Retardation

In the fatigue tests of specimens, sufficiently large tensile overload included in cyclic constant amplitude loading causes the retardation in fatigue crack growth. Crack retardation remains for some period of time after the overloading. The number of cycles in the retarded crack growth has been shown to be related to the plastic zone developed due to the overload. The magnitude of the elastic-plastic zone around the crack tip of DENT(Double Edge Notched Tension) specimen after a overloading was measured by ESPI(Electronic Speckle Pattern Interferometry) system. The fatigue crack growth rate also was measured by a traveling microscope. The relationship between the measured magnitude of plastic zone and the crack growth rate was compared with the equations proposed by Wheeler. Crack growth retardation model that was characterized by crack growth length and the size of plastic zone was proposed and compared with test result. From the research, the validity of proposed model is examined on crack growth retardation, and consequently fatigue life.

A Model of Fatigue Crack Growth Based on Damage Accumulation

2004 ◽  
Author(s):  
Satish Chand ◽  
K. N. Pandey
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Plastic Zone ◽  
Crack Growth ◽  
Damage Accumulation ◽  
Process Zone ◽  
Crack Tip ◽  
Cyclic Plastic ◽  
Cyclic Plastic Zone ◽  
Material Element

A fatigue crack growth model based on cumulative damage is presented, when a material element ahead of the crack tip, is approached by the tip of the crack. The cyclic plastic zone and process zone ahead of the crack tip are taken as the area where damage accumulation takes place when the material element, first, enters into the cyclic plastic zone and then into the process zone. During this period, the Coffin-Manson damage law in conjunction with Miner’s linear damage accumulation is used to determine the damage in the material element. A constant strain gradient was assumed along the process zone ahead of the crack tip and the size of process zone was taken to be variable and dependent on the range of stress intensity factor. For a cyclic loading, the effective crack driving force takes into consideration the crack tip blunting process. The model results are in good agreement with experimental data available in literature for a number of materials.

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