An experimental evaluation of fatigue crack growth

This paper examines the fatigue crack growth histories of a range of test specimens and service loaded components and concludes that in all cases, the crack growth shows, as a first approximation a linear relationship between the log of the crack length or depth and the service history (number of cycles). These cracks have grown from; semi- and quarter elliptical surface cuts, holes, pits and inherent material discontinuities in test specimens, fuselage lap joints, welded butt joints, and complex tubular jointed specimens and include cracks grown under uniaxial and biaxial loading. The implications of this exponential growth are discussed.