Analytical and numerical evaluation of stress intensity factor along crack paths in the cruciform specimens under out-of-phase cyclic loading

The paper presents the experimental results concerning fatigue crack growth in the cruciform plate specimens made of 18G2A (S355J0) steel. Two types of specimens were used, first with stress concentrator in form of central hole of 3.0 mm (with the minimum 1.86 mm wall thickness) in diameter and the second variant specimens without a hole (the minimum 1.25 mm wall thickness). The analytic and numerical methods were applied for description of fatigue crack growth rate. Simulation of crack growth in cruciform specimens were performed with the finite element method and the COMSOL software (up to the crack initiation), as well as using the boundary element method with the FRANC3D software (during propagation).