An energy-balance approach to the problem of fatigue-crack growth

An energy-balance approach to the problem of fatigue-crack propagation is considered here, the basic premise being that the energy equivalent of the work input in fatique over a period of time Δt must be greater than or equal to the energy dissipated in the form of heat together with the energy required to produce the plastic zone ahead of the crack tip and to create the necessary the surface for crack propagation over the same time period Δt. A fatigue-crack-growth (FCG) rate equation has been formulated based upon the above energy-balance concept. The fatigue-crack-growth rate is found to be inversely proportional to the plastic work and the energy requirement for the creation of new surfaces and directly proportional to the fatigue input energy. An experimental approach for determining the fatigue-crack-propagation rate using the energy-balance concept has been outlined.