The interaction of a crack front with a second-phase dispersion
TL;DR: In this paper, it was shown that a crack front increases its length by changing its shape when it interacts with two or more inhomogeneities in a brittle material, and an expression for the fracture energy was obtained.
Abstract: Observations are presented showing that a crack front increases its length by changing its shape when it interacts with two or more inhomogeneities in a brittle material. These observations are presented for both cleavage and conchoidal types of fracture. Based on these observations and the concept that a crack front possesses a line energy, an expression for the fracture energy is obtained. This expression shows that the fracture energy should increase as the distance between the dispersed inhomogeneities is decreased. Using the Griffith fracture criterion, this result is discussed for the case of strengthening a brittle material.
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TL;DR: In this article, the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate polymer composites are reviewed.
Abstract: There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.
2,767 citations
Cites background or methods from "The interaction of a crack front wi..."
...Lange and Radford [75] studied the fracture of alumina trihydrate (ATH) filled epoxy resins and reported that Gc was improved by adding the particles....
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...Lange’s equations also predict that, for a given Vp, small particles dp should give better toughening....
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...The mechanism of crack interaction with a second phase dispersion is qualitatively consistent with the results obtained by Lange and Radford [75] where two different types of fracture surfaces were observed....
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...The concept that crack pinning (bowing) could lead to increased fracture toughness was first postulated by Lange [43], subsequently refined by Evans [197] and later developed further by Green et al. [198,199] for different particle shapes....
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...A characteristic feature of crack pinning is the ‘‘tails” left behind the particles [22,42,43,75,199,203]....
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TL;DR: In this article, a fracture mechanics approach has been used to predict fracture toughness increases due to crack deflection around second phase particles, based on a determination of the initial tilt and the maximum twist of the crack front between particles.
1,287 citations
TL;DR: In this article, the authors discute des mecanismes de renforcement des ceramiques par pontage des fissures a l'aide de trichites and d'autres types de renforcants discontinus.
Abstract: On discute des mecanismes de renforcement des ceramiques par pontage des fissures a l'aide de trichites et d'autres types de renforcants discontinus. On montre que le renforcement par pontage des fissures peut etre combine avec d'autres mecaniques de renforcement (par exemple par transformation de phase) et que l'on peut obtenir des effets de synergie. La conception des materiaux renforces repose fortement sur le controle des proprietes des materiaux et des constituants microstructuraux
903 citations
TL;DR: In this paper, an epoxy resin, cured with an anhydride, has been modified by the addition of silica nanoparticles, and the measured modulus was compared to theoretical models, and good agreement was found.
777 citations
TL;DR: In this paper, a comprehensive study was carried out on series of nanocomposites containing varying amounts of nanoparticles, either titanium dioxide (TiO 2 ) or aluminium oxide (Al 2 O 3 ).
766 citations
References
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TL;DR: In this article, the authors investigated the effect of surface scratches on the mechanical strength of solids, and some general conclusions were reached which appear to have a direct bearing on the problem of rupture, from an engineering standpoint, and also on the larger question of the nature of intermolecular cohesion.
Abstract: In the course of an investigation of the effect of surface scratches on the mechanical strength of solids, some general conclusions were reached which appear to have a direct bearing on the problem of rupture, from an engineering standpoint, and also on the larger question of the nature of intermolecular cohesion. The original object of the work, which was carried out at the Royal Aircraft Establishment, was the discovery of the effect of surface treatment—such as, for instance, filing, grinding or polishing—on the strength of metallic machine parts subjected to alternating or repeated loads. In the case of steel, and some other metals in common use, the results of fatigue tests indicated that the range of alternating stress which could be permanently sustained by the material was smaller than the range within which it was sensibly elastic, after being subjected to a great number of reversals. Hence it was inferred that the safe range of loading of a part, having a scratched or grooved surface of a given type, should be capable of estimation with the help of one of the two hypotheses of rupture commonly used for solids which are elastic to fracture. According to these hypotheses rupture may be expected if (a) the maximum tensile stress, ( b ) the maximum extension, exceeds a certain critical value. Moreover, as the behaviour of the materials under consideration, within the safe range of alternating stress, shows very little departure from Hooke’s law, it was thought that the necessary stress and strain calculations could be performed by means of the mathematical theory of elasticity.
10,162 citations
TL;DR: In this article, a straight crack moving through an elastic medium is calculated and the stresses depend on the velocity and reduce to Inglis' solution when the velocity is zero, and the results may be applied to the spicular fracture of glass.
Abstract: Summary The stress field is calculated about a straight crack moving through an elastic medium. The stresses depend on the velocity and reduce to Inglis' solution when the velocity is zero. The results may be applied to the spicular fracture of glass.
663 citations
TL;DR: In this article, the double-cantilever cleavage technique was used to measure the fracture surface energy of six glasses and the results ranged from 3.5 to 5.3 J/m2 depending on the chemical composition of the glass and the temperature of the test.
Abstract: Fracture surface energies of six glasses were measured using the double-cantilever cleavage technique. Values ranged from 3.5 to 5.3 J/m2 depending on the chemical composition of the glass and the temperature of the test. The fracture surface energy increased with decreasing temperature and increasing Young's modulus; however, exceptions to this behavior were noted. The magnitude of the values obtained is discussed with respect to the theoretical strength of glass and possible irreversible effects at the crack tip such as stress corrosion and plastic deformation are considered.
481 citations