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Advanced Structural Analysis/Part I - Theory/Failure Modes/Fatigue/Crack Initiation/Loading/Load Spectra/Miner-Palmgren rule
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Load histories in real applications are often complex and irregular. The total fatigue effect of such loads can be estimated by the Miner-Palmgren rule, see the equation below. Fatigue failure is assumed to occur when the Miner-Palmgren equation is true.
Where:
a constant, often ranging between 0.33 and 3
the number of occurrences of a specific load cycle progression,
the fatigue life of a specific load cycle progression,
Shortcomings of Miner's rule
The Miner-Palmgren rule is rather rough and neglects several important qualities of a general load history. Among these properties are the order and shape of the individual cycles.