A General Theory of Fatigue Damage Accumulation

The aim of this presentation is to develop a general linear theory of isotropic cumulative failure. This involves a phenomenological consideration of fatigue damage accumulation under very general conditions. In order to accomplish this, it is necessary to extend the basic notion of cycle-dependent behavior for a harmonic stress variation to more complicated situations. The mean and alternating components of a conventional waveform are given a suitable interpretation to account for irregular stress-time variations. The state of stress also receives proper consideration to allow for independent variation of each tensor element. The entire program is motivated by a desire to achieve complete generality, and the systematic development of the analytical model is predicated upon the experimental observations and theoretical proposals of previous investigators. This provides a firm logical-empirical basis to support the proposals made in this investigation.