Synchrotron 3D characterization of arrested fatigue cracks initiated from small tilted notches in steel
Journal Title: Frattura ed Integrità Strutturale - Year 2015, Vol 9, Issue 33
Abstract
High resolution synchrotron X-ray tomography has been used to obtain 3D images of arrested cracks initiated at small artificial defects located on the surface of cylindrical steel specimens subjected to mode I fatigue loading. These defects consist in small semi-circular slits tilted at 0°, 30° or 60° with respect to the plane normal to the loading axis; all of them had the same defect size, area = 188 μm, where the area denotes the area of the domain defined by projecting the defect on a plane normal to the loading axis. Arrested cracks initiated from the notch were observed for all tilt angles at the surface of samples cycled at the fatigue limit (stress amplitude at which the specimen does not fail after 1×107 cycles). High resolution synchrotron X-ray tomography has been used to obtain 3D images of those small defects and non-propagating cracks (NPC). Despite the fact that steel is a highly attenuating material for X rays, high resolution 3D images of the cracks and of the initiating defects were obtained (0.65 m voxel size). The values of surface crack length measured by tomography are the same as those obtained by optical microscope measurements. The area values present the same tendency as the surface length of NPC, i.e. larger non-propagating cracks areas were observed in the softer steel. In the extreme case of 60º tilted defect, the crack fronts appear much more discontinuous with several cracks propagating in mode I until arrest.
Authors and Affiliations
P. Lorenzino, J. Buffiere, S. Okazaki, H. Matsunaga, Y. Murakami
Keywords
Related Articles
- EP ID EP122215
- DOI 10.3221/IGF-ESIS.33.27
- Views 34
- Downloads 0
Fatigue modelling for gas nitriding
The present study aims to develop an algorithm able to predict the fatigue lifetime of nitrided steels. Linear multi-axial fatigue criteria are used to take into account the gradients of mechanical properties prov...
Liquefaction mathematical analysis for improvement structures stability
The stability of any structure is possible if foundation is appropriately designed. The Bandar abbas is the largest and most important port of Iran, with high seismicity and occurring strong earthquakes in this territory...
Effect of molding processes on multiaxial fatigue strength in short fibre reinforced polymer
This study concerns the multiaxial static and fatigue strength properties. Short-glass-fibre-reinforced phenolic-resin composites (SGP) molded by injection and compression processes were subjected to tensiontorsio...
Damage propagation in a masonry arch subjected toslow cyclic and dynamic loadings
In the present work, the damage propagation of a masonry arch induced by slow cyclic anddynamic loadings is studied. A two-dimensional model of the arch is proposed. A nonlocal damage-plasticconstitutive law is ado...
Strain gradient elasticity within the symmetric BEM formulation
The symmetric Galerkin Boundary Element Method is used to address a class of strain gradientelastic materials featured by a free energy function of the (classical) strain and of its (first) gradient. With respectto...