On Fracture Analysis of Cracked Graphite Components under Mixed Mode Loading
07 Jul 2014-Mechanics of Advanced Materials and Structures (Taylor & Francis)-Vol. 21, Iss: 10, pp 781-791
TL;DR: In this paper, a new approach based on the maximum tangential stress (MTS) criterion has been employed for investigating mixed mode brittle fracture in materials like polycrystalline graphite.
Abstract: A new approach based on the maximum tangential stress (MTS) criterion has been employed for investigating mixed mode brittle fracture in materials like polycrystalline graphite. The new criterion has been examined using the experimental results reported in the literature for several graphites. The reported experimental data were obtained from fracture tests conducted using the centrally cracked Brazilian disk specimens. It is shown that the values of mixed mode fracture resistance predicted by the new criterion are in good agreement with the experimental results.
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References
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4,211 citations
"On Fracture Analysis of Cracked Gra..." refers background or methods in this paper
...4 test data: Graphite SA [34] New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
[...]
...They are the maximum tangential stress (MTS) criterion [7], the minimum...
[...]
...New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
[...]
...4 Test data: Graphite 7477 [34] New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
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...As mentioned earlier, the maximum tangential stress (MTS) criterion was first proposed by Erdogan and Sih [7] for brittle fracture in mixed mode I/II crack problems....
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TL;DR: In this article, it was shown that at the base of the crack in the direction of its prolongation, the principal stresses are equal, thus tending toward a two-dimensional (two-dimensional) hydrostatic tension.
Abstract: In an earlier paper it was suggested that a knowledge of
the elastic-stress variation in the neighborhood of an
angular corner of an infinite plate would perhaps be of
value in analyzing the stress distribution at the base of a
V-notch. As a part of a more general study, the specific
case of a zero-angle notch, or crack, was carried out to
supplement results obtained by other investigators. This
paper includes remarks upon the antisymmetric, as well
as symmetric, stress distribution, and the circumferential
distribution of distortion strain-energy density. For the
case of a symmetrical loading about the crack, it is shown
that the energy density is not a maximum along the direction
of the crack hut is one third higher at an angle ± cos^(-1)
(1/3); i.e., approximately ±70 deg. It is shown that at the
base of the crack in the direction of its prolongation, the
principal stresses are equal, thus tending toward a state of
(two-dimensional) hydrostatic tension. As the distance
from the point of the crack increases, the distortion strain
energy increases, suggesting the possibility of yielding
ahead of the crack as well as ±70 deg to the sides. The
maximum principal tension stress occurs on ±60 deg rays.
For the antisymmetrical stress distribution the distortion
strain energy is a relative maximum along the crack and
60 per cent lower ± 85 deg to the sides.
2,693 citations
"On Fracture Analysis of Cracked Gra..." refers background in this paper
...Williams [41] showed that the elastic stresses around the crack tip can be expressed as an infinite series expansion....
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TL;DR: In this paper, the authors investigated the general problem of crack extension in a combined stress field where a crack can grow in any arbitrary direction with reference to its original position, and showed that the direction of crack growth and fracture toughness for the mixed problem of Mode I and Mode II are governed by the critical value of the strain-energy-density factor.
Abstract: This paper deals with the general problem of crack extension in a combined stress field where a crack can grow in any arbitrary direction with reference to its original position. In a situation, when both of the stress-intensity factors,k
1,k
2 are present along the crack front, the crack may spread in any direction in a plane normal to the crack edge depending on the loading conditions. Preliminary results indicate that the direction of crack growth and fracture toughness for the mixed problem of Mode I and Mode II are governed by the critical value of the strain-energy-density factor,S
cr. The basic assumption is that crack initiation occurs when the interior minimum ofS reaches a critical value designatedS
cr. The strain-energy-density factorS represents the strength of the elastic energy field in the vicinity of the crack tip which is singular of the order of 1/r where the radial distancer is measured from the crack front. In the special case of Mode I crack extensionS
cr is related tok
1c alone asS
cr = (κ − 1)k
1
2
/8μ. In general,S takes the quadratic forma
1 1
k
1 + 2a
1 2
k
1
k
2 +a
2 2
k
2 whose critical value is assumed to be a material constant. The analytical predictions are in good agreement with experimental data on the problem of an inclined crack in plexiglass and aluminum alloy specimens. The result of this investigation provides a convenient procedure for determining the critical crack size that a structure will tolerate under mixed mode conditions for a given applied stress.
2,066 citations
"On Fracture Analysis of Cracked Gra..." refers background in this paper
...strain energy density (SED) criterion [8], and the maximum energy release rate or G criterion [9], to name a few....
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01 Jan 1974
TL;DR: In this article, the energy release rate for a crack subjected simultaneously to mode I and mode II conditions is computed by path independent integrals, using the elastic solution of a deflected crack, having a main branch and a propagation branch.
Abstract: : The energy release rate for a crack subjected simultaneously to mode I and mode II conditions is computed. The energy was computed by path-independent integrals, using the elastic solution of a deflected crack, having a main branch and a propagation branch. The elasticity solution was obtained from the functional integral equations by the process of iterations. This process leads to a point-wise exact solution in the limit as the propagation branch goes to zero. Using the Griffith-Irwin criterion, incipient paths of propagation of such a crack were obtained from the maximum value of the energy release rate. An experiment, which gives a pure mode II condition at the tip of the crack, was devised. The results were in excellent agreement with the theory. The energy release rate, in parametric form, can be used for any crack subjected to mode I and mode II loading conditions. (Author, modified-PL)
735 citations
"On Fracture Analysis of Cracked Gra..." refers background or methods in this paper
...4 test data: Graphite SA [34] New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
[...]
...New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
[...]
...4 Test data: Graphite 7477 [34] New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
[...]
...strain energy density (SED) criterion [8], and the maximum energy release rate or G criterion [9], to name a few....
[...]
...4 Test data: Graphite SM1-24 [34] New criterion GMTS criterion [40] MTS criterion [7] G criterion [9]...
[...]
TL;DR: In this article, an analysis is made of the cracked Brazilian disk test and various approximations for the stress intensity factors of a crack aligned at any direction to the applied load are given.
Abstract: An analysis is made of the cracked Brazilian disk test. Explicit results are given for the stress intensity factors of a crack aligned at any direction to the applied load. Various approximations are considered and a simplified ‘short crack’ approximation is shown to be accurate for l/a≤0.3 (l is crack length, a the disk radius). At certain angles it is found that crack closure should occur and as a frist step the effect of friction is taken into account for such cases by using this short crack approximation. Finally, experimental results are presented to confirm and elucidate the use of this specimen geometry for the problem of combined mode fracture.
453 citations