Fatigue (Miner’s Rule)

Description

In materials science fatigue occurs when a material is subjected to repeated loading and unloading. The failure of the material occurs when there are k groups of different stress magnitudes in a spectrum, Si (1 ≤n ≤ k), each of them contributing ni(Si) cycles, if Ni(Si) is the number of cycles to failure of a constant stress reversal Si. C is experimentally found to be between 0.7 and 2.2. Usually for design purposes, C is assumed to be 1.

Related formulas

Variables

kNumber of different stress groups (dimensionless)
nSpectrum of stress levels in each group (dimensionless)
fnNumber of cycles accumulated at stress Si (dimensionless)
NnNumber of cycles to failure of a constant stress reversal Si (dimensionless)
CFraction of life consumed by exposure to the cycles at the different stress levels (dimensionless)