Part-circular surface cracks in round bars under tension, bending and twisting

Abstract

International audienceCircular-fronted cracks in round bars subject to tension, bending and twisting are considered. Numerical expressions are given allowing the calculation of stress intensity factors $K_I$, $K_{II}$, $K_{III}$ at every point on the crack front for a wide range of crack geometries. Comparisons are made with analytical, experimental and numerical results available in the literature. Crack shapes satisfying the iso-$K_I$ criterion are also determined, making it possible to investigate the problem of crack growth behaviour under tensile or bending fatigue loads

High Strength Steels Fracture Toughness Variation by the Media

“…For the case of a cylindrical geometry of the material, the calculation of the stress intensity factor and the criterion of fracture can be calculated through Astiz, Valiente and Elices's equation [1,7] or through Levan and Royer's equation [8]. The above mentioned authors have assumed that cracks along the whole perimeter of the specimen are formed and the superficial cracks have semi-ellipse shape (Figure 4).…”

Propagation Lifetime from the Surface and Internal Defects in the Ultra High Cycle Fatigue Regime~!2008-03-10~!2008-05-06~!2008-07-03~!

“…The crack shape factor for a surface defect (Fig. 3b) integrates the stress gradient of the bending load [15]. In case of the sub surface initiation (Fig.…”

“…The initial circular crack radius is 14 μm, which is equivalent to area = 17 μm. K is calculated, using the appropriate value of the crack shape factor Y [15,16], and in case of an internal circular crack under tension (Fig. 3a), Y = 2/ .…”

Environmentally-assisted fatigue crack growth in prestressing steel wires

“…Growth of surface cracks in round bars due to fatigue can be modelled using different criteria, e.g., prediction of the 90° intersecting angle of the crack with the surface or the iso-K criterion along the crack front [8]. Another criterion is based on the crack growth according to the Paris-Erdogan law [9], considering the crack advance perpendicular to the crack front, assuming elliptic geometry for the growing crack [10,11] or avoiding the shape hypothesis, i.e., allowing the crack to grow with any shape [12].…”