Effects of Test Parameters on Fracture and Fatigue Characteristics of a SE(T) Steel Specimen

The understanding of crack behavior under fatigue remains a critical issue in addressing the performance of bridge structures. In this study, effects of test parameters on the stress intensity factor (K) of a modified single edge notched tension [SE(T)] steel specimen with a through width notch was experimentally, analytically and numerically investigated. Equations were developed to include the effects of fix boundary condition on K and crack mouth opening displacement (CMOD) of the crack. Effects of axial and angular misalignments on K along the crack length were examined and a progressively decreasing influence on K was observed when the crack size increased. Two dimensional (2D) and three dimensional (3D) Finite Element Method (FEM) was used to evaluate the effect of the two end bounding conditions on K value of non-uniform crack fronts. Influence of ungripped length of the specimen on K was evaluated and showed to be more substantial for short specimens. Finally, a framework was proposed to map the crack front evolution through high cycle fatigue tests for a modified SE(T) specimen with initial crack inclination.