Abstract:

ESDU 95006 introduces the theory of linear cumulative damage, the Palmgren-Miner Rule that hypothesises that the damage inflicted by any cycle in a variable amplitude loading sequence is the same as that inflicted by the same cycle in a constant amplitude loading. The application of damage summation to nominal and local stresses (and strains) taking into account, for example, yielding at a notch is described. Once the stress or strain history is established cycle counting is possible and the damage sum can be calculated. Two algorithms for cycle counting are defined, the rainflow method and the range-mean pairs technique. Methods of taking into account the effect on endurance of residual stress, fretting, notch size, bending and surface treatment are suggested. Fully-worked examples are given of both the stress-life and the strain-life methods.