Variable Amplitude

These analyzers compute fatigue lives for variable amplitude or spectrum loads. There are three primary methods for estimating the fatigue resistance of components and structures, stress-life, strain-life and crack growth. eFatigue does them all. Just upload your load history file and let eFatigue do the fatigue analysis.

Variable amplitude fatigue analysis is based on the same concepts as constant amplitude fatigue analysis with the addition of cycle counting and damage summation. In a variable amplitude loading history, equivalent constant amplitude cycles must be identified. This is accomplished with a process called rainflow counting. Once cycles have been identified, the fatigue damage for all of the cycles in the loading history are summed with Miners linear damage rule to obtain the damage for the entire loading history.

In addition to fatigue lives, histograms of the cycles and fatigue damage are provided.

Loading histories may be entered in text boxes, pasted from the clipboard or read from files. Provisions have been made to read from a variety of file formats.

Finders are provided to obtain the necessary input information for material properties and stress concentration or stress intensity factors.

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Fatigue Analyzers

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  • Stress-Life
    Use this method for long life situations where the strength of the material and the nominal stress control the fatigue life.
  • Strain-Life
    This method is used for finite fatigue lives where plasticity around stress concentrations is important.
  • Crack Growth
    Use this method to determine how long it will take a crack to grow to a critical size.
  • Multiaxial Stress-Life
    Use this method for long life situations where the strength of the material and the nominal stress control the fatigue life.
  • Multiaxial Strain-Life
    This method is used for finite fatigue lives where plasticity around stress concentrations is important.

Finders

Technical Background