Estimation of the Fatigue Life of a Thick-Walled Cylinder Subjected to Repeated Internal Pressure

Abstract

Experimental data available on fatigue crack growth may be described by an equation of the form d a/d N = B(Δ K) m, where d a/d N is the rate of crack growth per stress cycle, Δ K is the range of stress intensity factor, and B and m are material properties. This relationship has been used to estimate the fatigue crack propagation lives of thick-walled cylinders subjected to repeated internal pressure. By using an approximate value for the stress intensity factor, and considering the high local stresses at the crack due to pressurized oil, close correlation is obtained between the estimated and experimental fatigue lives. Design curves are obtained, by which the fatigue life of such a cylinder may be estimated from a knowledge of the transverse uniaxial fatigue limit and fracture toughness properties of the cylinder material, as well as the diameter ratio of the cylinder and the repeated pressure.