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Journal of Materials Science

, Volume 29, Issue 24, pp 6501–6504 | Cite as

ΔKol level effects on fatigue crack propagation

  • Kyong Y. Rhee
Papers

Abstract

In order to determine the effects of ΔKol level on fatigue life, a single peak load was applied at distinct ΔK levels of 7.8×10.3 and 9.8×103 p.s.i. in1/2. Here the ΔKol level was defined to be a ΔK level at which overload was applied. Three different overload ratios of 1.5, 2.0, and 2.5 were used to determine the overload ratio effect on the recovery factor. The result showed that the recovery factor, Z, was linearly related to ΔK as Z = qΔK+Zo, where q was a function of overload ratio. The value of q decreased as the overload ratio increased in a given ΔKol level and seemed to be an important factor as well as retardation cycles in determining the fatigue life. For the same overload ratio, specimens that underwent overload at a smaller ΔKol level showed more improved fatigue life.

Keywords

Polymer Fatigue Fatigue Crack Fatigue Life Material Processing 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

a

Crack length

a*

Overload affected zone size

B

Specimen thickness

(da/dN)ca

Crack growth rate due to constant amplitude fatigue load

(da/dN)ol

Crack growth rate after overload is applied

E

Young's modulus

K

Stress intensity factor

Kmin

Minimum stress intensity factor

Kmax

Maximum stress intensity factor

ΔKol

ΔK level at which overload is applied

N

Number of cycles

ND

Number of delayed cycles

Nf

Number of cycles needed for a specimen to be completely fractured

rp

Assumed plastic zone size

S

Load

σys

Yield stress

W

Width

Z

Recovery factor

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References

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • Kyong Y. Rhee
    • 1
  1. 1.Agency for Defense DevelopmentYuseongKorea

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