Micro and Macro Fracture Mechanics Approach to Brittle Fracture and Fatigue Crack Growth

Yokobori, Takeo; Konosu, Shinji; Yokobori, A. T.

doi:10.1016/b978-0-08-022136-6.50045-7

Cited by 24 publications

(30 citation statements)

References 9 publications

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“…Based on the analyses of dislocation dynamics under the cyclic load condition, temperature and load frequency dependences of fatigue crack growth rate have been theoretically derived (21) , which is in good agreement with the experimental law of fatigue crack growth rate (26) . Furthermore, taking account for the effects of multiple slip lines and strain hardening under cyclic loading, the theoretically proposed law (21) was found to be quantitatively in good agreement with the experimental law (26) . On the other hand, dynamic dislocation behaviors during unloading process and the effect of its behavior on the characteristics of fatigue crack growth rate have not yet been clarified.…”

Section: Introductionsupporting

confidence: 52%

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The Effect of the Interaction between Dislocations and Hydrogen Around a Crack Tip on Hydrogen Embrittlement Under Cyclic Loading Condition

Taketomi

Yokobori

Takagi

2007

JMMP

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For steels with lower yield stress, transgranular facet like fracture sometimes occurs under corrosive conditions. The occurrence mechanism of the transgranular facet like fracture has been analytically clarified under constant stress rate condition based on the concept of mechanical interaction between dislocations and hydrogen. In this paper, the analyses of the mechanical interaction between dislocations and hydrogen around a crack tip under cyclic loading condition were conducted to clarify the effect of stress wave forms on the feasibility of hydrogen embrittlement. This analysis showed the typical pile-up of dislocations occurs at the site of hydrogen similar as that under monotonous applied loading condition. Concerning the concentration of dislocations at the site of hydrogen atom, the dislocation pile-up intensity factor amplitude ∆A and power coefficient value of the singularity of dislocation density n were defined. ∆A under fatigue condition was found to concern the feasibility of the occurrence of facet like fracture due to dislocation pile-up caused by the interaction between dislocations and hydrogen. Furthermore, the condition of Fast-Slow stress wave form was found to promote the facet like transgranular fracture as compared with that of Slow-Fast stress wave form.

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Section: Introductionsupporting

confidence: 52%

“…Part of author previously proposed a theory of fatigue crack growth based on dislocation dynamics (21) .…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Interaction between Dislocations and Hydrogen Around a Crack Tip on Hydrogen Embrittlement Under Cyclic Loading Condition

Taketomi

Yokobori

Takagi

2007

JMMP

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“…According to fracture dynamics, fracture in brittle materials occurs as the result of stress concentration in the area around the crack tip. 29 The degree of this stress concentration is defined as stress expansion coefficient K 1c• K 1c is shown in eqn (4) as a critical stress expansion coefficient for the time when the stress concentration at the crack tip begins to cause a fracture.…”

Section: Jlmmentioning

confidence: 99%

Properties and Applications of Silicon Carbide Ceramics

Yamada¹,

Mohri²

1991

Silicon Carbide Ceramics—1

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“…The fatigue fracture toughness [1][2][3][4][5][6], Kfc, corresponding to the final fracture, and the threshold stress intensity, AKth, below which crack propagation cannot be detected, are the parameters characterizing this relation. These two values are thought to be related with each other, however, this correlation has not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

Fatigue fracture toughness and crack propagation rate

et al. 1987

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Fatigue crack growth rate, da/dN, of two high strength steels were examined in a laboratory air at different stress ratios, covering almost the entire range of stress intensity, AK, from nearly threshold value, AKth, to final fracture. The fatigue fracture toughness, AKfc, corresponding to the final fracture in fatigue, was also determined. The lower the AKfc, the higher da/dN and reduced AKth are revealed.This correlation was analyzed quantitatively based on the four parameter Weibull function. And the stress ratio dependency of the fatigue crack propagation curve can be cleared in a successful manner.The fatigue characteristic stress intensities, Ke and Kv, are proposed to define the transition behaviour in fatigue crack growth curve, from so called region 1 to 2, and from region 2 to 3, respectively. Especially the Kv value can be specified to be the 0.63Kfc.

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Micro and Macro Fracture Mechanics Approach to Brittle Fracture and Fatigue Crack Growth

Cited by 24 publications

References 9 publications

The Effect of the Interaction between Dislocations and Hydrogen Around a Crack Tip on Hydrogen Embrittlement Under Cyclic Loading Condition

The Effect of the Interaction between Dislocations and Hydrogen Around a Crack Tip on Hydrogen Embrittlement Under Cyclic Loading Condition

Properties and Applications of Silicon Carbide Ceramics

Fatigue fracture toughness and crack propagation rate

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