Fatigue of Welded Components and Structures-Current Status

Structural components such as in bridges, cranes, engines, pressure vessels and offshore structures are often subjected to cyclic loading Fatigue failures generally occur at stress concentration sites in the components The geometrical and metallurgical states of welds make them prone to fatigue failures owing to stress concentrations caused by weld shape and discontinuities. Moreover, welding introduces unfavourable tensile residual stresses, often of yield magnitude, which increases the severity of the applied fatigue loading. As a result, both applied compressive and tensile stresses can be equally damaging. In addition, the existence of defects in weld eliminates the fatigue crack initiation stage, and hence, the life IS predominantly governed by fatigue crack propagation.