Stress Concentration Effect in StrainBased Fatigue

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Stress Concentration Effect in Strain-Based
Fatigue

• Fatigue processes generally initiate
  preferentially in stress concentrations
• Bolt holes, rivet holes, threads, fillets,
  radii, weld roots, pores, inclusions, surface
  scratches, etc. (Notch)
• The nominal (far field) strain may remain elastic
  in service, but the strains are often plastic in
  the notch roots.

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Notch
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Material Behaviour at Notch Root
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Stress-Strain at Notches
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Solution For Notch Strainin Plastic regime

• Neubers rule
• Glinkas

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Neubers Rule

• If nominal strains remain elastic
• For REVERSED loading

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Fatigue Analysis of Notched ComponentSimple
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Fatigue Analysis of Notched ComponentComplex
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Fatigue Fracture Surfaces
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Fatigue Fracture Surfaces
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Fatigue Fracture Surfaces