A general fatigue analysis procedure is provided in WRC Bulletin 474 that can be used for life estimation for structures containing welded joints under arbitrary loading conditions. For variable amplitude loading@ conventional cycle counting methods and Miner's rule summation of damage can be applied. The method is general and can also be used with other cumulative damage theories@ structural reliability methods and probabilistic analysis@ etc. The mesh-insensitive structural stress method discussed in this document provides a robust calculation procedure for capturing the stress concentration effects on fatigue behavior of welded joints. Its effectiveness is demonstrated by not only consolidating the pipe weld S-N data relevant to ASME codes@ but also consolidating the pipe data with plate joint data collected from drastically different thicknesses@ loading modes@ and joint configurations. The mesh-insensitive structural stress method is developed based on equilibrium considerations by extracting equilibrium-equivalent membrane and bending components at a weld@ where severe stress concentration can induce significant variations in conventional FE stress calculation methods. In doing so@ the structural stress parameter can be viewed as an equivalent far-field stress in fracture mechanics context. Thus@ an effective fatigue damage parameter can be formulated in the master S-N curve approach presented
BULLETIN 474-2002 history
2002BULLETIN 474-2002 MASTER S-N CURVE METHOD FOR FATIGUE EVALUATION OF WELDED COMPONENTS