Abstract
62 level block fatigue loadings in which waveform were approximating to the Rayleigh distribution of peak (distribution factor=0.25, 0.5 and 1) were applied on center cracked transverse butt welded joints in which tensile residual stresses were always induced at the crack tip. It was revealed that the fatigue crack propagation rate, da/dn*, could be estimated by the result obtained at constant amplitude tests assuming linear cumulative damage law. That is,
da/dn*=C(ΔK*eqm-ΔKmth)whereΔK*eq={(ΣΔKmi ·ni)/ni}1/m,
ni=0 at ΔKi≤ΔKth or ni=ni at ΔKi>ΔKth.
