A General Fatigue Theory and Its Application to Out-of-Phase Cyclic Loading

Abstract

Results of an experimental investigation of a constant-amplitude, fully reversed biaxial tension-compression out-of-phase cyclic loading are presented first. An energy-based fatigue theory is extended to include nonproportional (out-of-phase) cyclic loading. Finally, a constitutive model is presented to predict the cyclic multiaxial stress-strain response, and to calculate the energy based damage parameter. Thus, a general theory, applicable to uniaxial, proportional, and nonproportional multiaxial cyclic fatigue is presented. The predicted results are in fairly good agreement with the constant amplitude test data. A few uniaxial fatigue tests and an out-of-phase cyclic test are required to specify material constants of the theory.