CYCLIC CRACK RESISTANCE OF WELDED-JOINTS WITH NONUNIFORM FIELDS OF RESIDUAL WELDING STRESSES

The use of linear elastic fracture mechanics to describe the kinetics of fatigue fracture of welded joints with high welding residual stress es (WRS) is experimentally evaluated in this paper. A correction analy sis is used to show that the crack propagation rate of cracks in joint s, as a function of the applied stress intensity factor, is linear on a log-log scale in the Paris regime when non-uniform fields of WRS are superimposed on the applied cyclic loading. It is shown that crack gr owth rates in joints with high WRS do not depend on the characteristic s of the loading cycle. The parameters of the Paris exponential equati on are determined by the initial WRS distribution, by the range of cyc lic stresses and by the load ratio. A method for calculating the cycli c crack resistance of joints is proposed which explicitly allows for a non-uniform field of WRS that influences the fatigue crack growth rat e.