Concept of Fatigue Effective Stress and Constitutive Equation of Damaged Material

Abstract

Effective stress is one of the most important parameter in damage mechanics. An application of the concept of effective stress forms the basis for describing the mechanical behavior of damaged material by constitutive equations of an undamaged material. The present paper discusses the definition of effective stress in damage mechanics and its physical meaning. Through an analysis of the physical pattern of damage and its evolution it is shown, that such a definition is unsuitable for fatigue damage problems. The authors think that the effective stress should be based on equivalent life for fatigue problems, thereby define the concept of effective stress in fatigue damage according to the concept of remainder life.