A finite element analysis of fatigue crack arresters in steel structures

A cyclic elastic-plastic two-dimensional finite element model was utilized to simulate the effect of welded arrest stiffeners on crack tip deformation (CTD) in cracked plates. Two different types of cracked plates, single edge cracked plates (SECP) and centrally cracked plates (CCP), were analyzed in the plane stress condition to study the effect of specimen geometry on the efficiency of welded arrest stiffeners. Different stiffened plate geometries, subjected to the same stress intensity factor (SIF), were analyzed to study the efficiency of welded arrest stiffeners as a function of the stiffener's dimensions and its location with respect to the crack tip (CT). The efficiency of a welded arrest stiffener was increased by increasing its width and thickness and by decreasing its length. The amount of that increase was dependent on the type of cracked plate, a/w, and the stiffener's location. Correlations of the monotonic CTOD and PDZ were developed as a function of the stiffener's dimensions and location, and plate geometry. Two different idealizations, stiffened panels and welded arrest stiffeners, were analyzed to compare the efficiency of the stiffeners in each case. In the case of welded arrest stiffeners, the stiffeners were attached to the main plate by different techniques based on the concept of residual stresses to increase the efficiency of the stiffeners.