The Role of Energy Related Parameters in Life

There are several methods for increasing the fatigue lives of cracked and uncracked metallic components. One method involves the use of external bonded patches, whilst for fastener holes, cold expansion of the holes is often used. The present paper examines the stress and strain fields around a cold expanded hole and a centre cracked panel after a large overload and shows that in both cases the strain energy density becomes out of phase with the external work.