Accelerated block-load fatigue programs for wire ropes

The article summarizes some applications of the cumulative damage theory, indicating several of them suggested in the past with some recent proposals. As is known, the study of the fatigue phenomena can be carried out by means of procedures based on the concept of damage which rests on the assumption that each period in the service life of a structural or of the test piece subjected to repeated stresses can be correlated with a well defined physical state that is a function of maximum endurance till collapse at the stress level being considered: the damage. It is a function of the current state, variable from zero to one, expressed as the ratio between the number of repetitions of the damaging action (at a given time) and the number of repetitions leading to collapse, and has the properties of equivalence (different phenomena are equivalent if they produce the same darnage) and cumulability (partial damages of the same origin cumulate linearly) .

Author: U. Rossetti