Crack front curvature: Influence and effects on the crack tip fields in bi-dimensional specimens

• Published in: International journal of fatigue Vol. 44; pp. 41 - 50
• Main Authors: Camas, D., Garcia-Manrique, J., Gonzalez-Herrera, A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2012; Elsevier
• Subjects: Applied sciences; Crack front curvature; Curvature; Exact sciences and technology; Fatigue; Fatigue failure; Finite element analysis; Fracture mechanic; Fracture mechanics; Fractures; Mathematical analysis; Mathematical models; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Out-of-plane stress; Plastic zone size; Plastic zones; Stresses; Three dimensional; Crack front curvature; Plastic zone size; Fracture mechanic; Finite element analysis; Out-of-plane stress; Fracture mechanics; Rupture; Mechanical properties; Fatigue; Modeling; Plasticity zone; Finite element method; Plasticity; Crack tip
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2012.05.012

► We study the influence of the crack front curvature in through cracks on fracture. ► A CT specimen is studied by means of 3D finite elements using an ultrafine meshing. ► Three-dimensional effects and transition along the thickness is analysed. ► There is a triple dependence on load applied, specimen thickness and crack front curvature. ► Plastic zone and dominance of plane strain state depend on these three parameters. Crack front curvature is evidence in most experimental crack advance test. When classical linear elastic fracture mechanic theory deals with bi-dimensional crack configurations, it ignores the three-dimensional effects of crack propagation. Issues as the influence of the specimen thickness and the crack front curvature are not considered. Previous numerical studies have shed light on out-of-plane plastic zone development or stress state. Nevertheless, these numerical studies are based on the assumption that the crack front is ideally straight; despite it is well known that the crack front has some kind of curvature. In the present work, a CT aluminium specimen has been modelled three-dimensionally and several calculations have been made considering a huge combination of different single load levels, specimen thicknesses and crack front curvatures. Due to the abrupt transition from plane strain to plane stress, an ultrafine mesh along the thickness has been applied. The analysis of the evolution of the plastic zone and the stress state along the thickness provides information about the combined influence of these parameters on fracture mechanics.