Strain-Life Analysis (E-N)

The Strain-Life, or in short, E-N approach typically relates to situations where some of the cyclic loads are relatively large and have significant amounts of plastic deformation associated with them, together with relatively short lives. This type of behavior is commonly referred to as low-cycle or strain-life fatigue, although it is perfectly valid to use the E-N approach even in a high-cycle situation. The transition from low-cycle (E-N only) to high-cycle (S-N and E-N) fatigue behavior generally occurs in the range of 103 to 104 cycles

Low Cycle Fatigue

The Strain-Life method is applicable to a wide range of problems including low-cycle fatigue, where the local elastic-plastic strain controls the fatigue life. The standard E-N method uses the Coffin-Manson-Basquin formula, defining the relationship between strain amplitude εa and the number of cycles to failure Nf. Material models can also be defined using general look-up curves. This enables the ability to interpolate multiple material data curves for factors such as mean stress or temperature. Features include:

  • Material models
    • Standard E-N
    • E-N Mean multi-curve
    • E-N R-ratio multi-curve
    • E-N Temperature multi-curve
    • E-N Gray Iron
  • Strain combination methods or critical plane analysis
  • Stress-strain tracking for accurate cycle positioning
  • Back calculation to target life
  • Multiaxial damage models
    • Wang Brown
    • Wang Brown with Mean
  • Mean stress corrections
    • Morrow
    • Smith Watson Topper
    • Interpolate multiple curves
  • Plasticity corrections
    • Neuber
    • Hoffman-Seeger
    • Seeger-Heuler
  • Multiaxial assessment
    • Biaxial
    • 3D Multiaxial
    • Auto-correction