Static Fatigue

Abstract

Static fatigue considers fracture occurring at a stress level less than that it is required for tensile fracture. Static fatigue is also termed delayed fracture and often the influence of hydrogen on the premature failure of components is observed; classical example for delayed fracture in steel occurs by hydrogen. Static fatigue failure depends on the presence of water vapor in the air also. In other words static fatigue is caused by the combined action of tensile stress and moisture on a component in particularly ceramics. Static fatigue can be induced with constant stress acting over time and in such tests the goal is to determine the time-to-failure of a specimen. In such tests a series of specimens at decreasing constant loadings results in higher lifetimes allowing the determination of the time to failure of a component. In ceramics, static fatigue is one of the important factors for life determination. All substances considered in this book are exposed to static fatigue.