Fatigue behavior of the transverse stiffener subjected to constant amplitude loading

Abstract

Objectives of this study are to examine the fatigue behavior of the transverse stiffener in comparison with other previous studies. The shape of fatigue cracks depended upon the number of crack initiation sites along the weld toe. Fatigue cracks initiated at a corner had quarter-elliptical fronts. And, the crack propagated through the thickness of the main plate until the remaining ligament eventually fractured at an average net section stress nearly equal to the tensile strength. The constant amplitude fatigue limits for the specimens tested atfmin=14 N/mm2 andfmax=290 N/mm2, were respectively predicted with the mean regression line,s=0.084,m=4.097, using by the number of run outs in percent. By changing fromfmin=14 N/mm2 tofmax=290 N/mm2, the fatigue strength decreased clearly in the finite life region and so did the lower bound fatigue limit fromFrl=110 to 83 N/mm2. For the effect of the weld type, it was also found that the excellent quality of automatic welding resulted in a large root radius at the weld toe and thus significantly increased the fatigue strength of both stiffeners from category C to B'