Stress intensity factors K I and K II for cracks at the tips of parallel pore channels with starlike cross-sections

Borovik, V. G.

doi:10.1007/s11106-011-9310-4

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…Errors in calculating the SIF for these points are not estimated in this study; therefore, the corresponding values of the SIF are not represented in the plots. Errors in calculating the SIF for other points of the crack front were considered earlier (see Borovik 2011b).…”

Section: Resultsmentioning

confidence: 99%

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Three-dimensional numerical analysis of stress intensity factors at the intersection of a crack and pore channels with star-like cross-section

Borovik

2012

Int J Fract

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The three-dimensional numerical analysis of stress intensity factors (SIF) at the intersection of a main crack (MC) and pore channels has been performed. Each channel consists of three channel cracks (CC) united by their mouths on the channel axis. It has been shown that the rupture of the MC face by the differently oriented CC gives rise to the local SIF at the MC front that is differs more than twice from the mean SIF. The maximum local SIF for the CC the plane of which is parallel to the MC front is four times higher than the SIF for the CC the plane of which is perpendicular to the MC front. The total shearing and tearing mode SIF at the CC front has three local maxima. One maximum is located at the intersection of the CC front with a plane, to which the MC face belongs. Additional peaks are located at some distance from both sides of this plane.

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Section: Resultsmentioning

confidence: 99%

“…Peculiarities of the discretization of the unit cell were described earlier (Borovik 2011a). Sizing FE for the similar unit cell to reduce errors in calculating the SIFs was considered by Borovik (2011b).…”

Section: Model Of the Materials And The Calculation Proceduresmentioning

confidence: 99%

Three-dimensional numerical analysis of stress intensity factors at the intersection of a crack and pore channels with star-like cross-section

Borovik

2012

Int J Fract

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“…The influence of different dimensions of crack branches on the effective elastic properties was investigated. For the same material and the computer model, Borovik [7] analysed the effect of crack branch lengths on SIF.…”

Section: Introductionmentioning

confidence: 99%

Analysis of closed branched and intersecting cracks by the boundary element method

Fedeliński

2022

Acta Mech

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The boundary element method (BEM) and a computer code for the analysis of plates with closed branched and intersecting cracks are developed. The BEM enables simple and accurate modelling of cracked plates by using boundary elements. Contact tractions between crack surfaces are computed using an iterative procedure. Stress intensity factors (SIFs) are determined using the path-independent integral. Three numerical examples are studied: a star-shaped crack in a square plate, multiple interacting cracks in an infinite plate and randomly distributed and intersecting cracks in a square plate. The examples demonstrate the simplicity of numerical modelling, the accuracy of the method and the possible applications. The influences of load directions, distances between cracks and the contact of the crack surfaces on SIF are investigated. For the plate with randomly distributed cracks, the effective elastic properties are additionally computed by considering or neglecting contact of crack surfaces. The results show that the importance of the contact procedure depends on how the cracked material is loaded.

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“…At a tension which results from loading of the material cell along and across channels, gained during the present SIF work will be summed up with SIF from external loadings in the plane, perpendicular to the channels axis (Borovik (2011) in press).…”

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Stress Intensity Factors at the Intersection of a Crack and Pore Channels with Various Cross-Sections

Borovik

2011

Int J Fract

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Changes of stress intensity factors (SIF) of a flat main crack with rectilinear front which cuts the system of regular parallel pore channels normally to their direction are determined. Channels had cross-sections in the form of a circle, an equilateral triangle, a triangle with the concave sides of constant curvature and a starlike crack. It is shown that SIF on the main and channel cracks may have comparable values.Keywords: stress intensity factor, crack, pore channel, intersections of cracks. 1. Introduction. Materials with unidirectional fibrous structure have high strength characteristics in the direction of fibers. They contain pore channels which are parallel to fibers. In some processes of manufacturing of such materials these channels are used for removal of gaseous products of pyrolysis from material volume (see, for example, Ishikawa et al. (1998)). Extremely high resistance to fracture makes these materials interesting for many applications.High resistance to fracture under tension along fibers is achieved by changing Mode I conditions on the main crack to a sliding or in-plane shearing mode (mode II) and/or tearing or out-of-plane shearing mode (mode III) after crossing a fiber. There are two ways such transformation may proceed (A) by forming "weak" boundaries normal to the expected direction of the main crack growth. Solid or porous coatings and intermediate layers are used for this purpose (see, for example, Davis et al. (1995), Grigoriev et al. (2006), and (B) by residual stresses near "strong" boundaries between microstructure elements (Tu et al (1996)).Note that carbon fibers, known for their high strength, have significantly different binding energy of carbon atoms in the bearing layers (graphite planes) and between the layers (planes). That is the structure of a carbon fiber is inherent for materials with "weak" boundaries between load bearing elements of microstructure.Growth of cracks of sliding and tearing on boundaries of fibers leads to abbreviation of sizes of area of a stress concentration in a plane of the main crack and to its elongation in a direction of fibers. Magnitude of this abbreviation/lengthening is defined by relations of crack growth resistances (normal and shift) a material of fibers and boundaries between them, and also a friction of surfaces of cracks. This mechanism promotes more to a uniform distribution of stresses between elements of a materials structure. The most uniform distribution of normal stresses is achieved in the fibers and wires of ropes and cables.The friction of surfaces of cracks in the course of their relative shear leads to increase a fracture energy of a material.

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Stress intensity factors K I and K II for cracks at the tips of parallel pore channels with starlike cross-sections

Cited by 5 publications

References 11 publications

Three-dimensional numerical analysis of stress intensity factors at the intersection of a crack and pore channels with star-like cross-section

Three-dimensional numerical analysis of stress intensity factors at the intersection of a crack and pore channels with star-like cross-section

Analysis of closed branched and intersecting cracks by the boundary element method

Stress Intensity Factors at the Intersection of a Crack and Pore Channels with Various Cross-Sections

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