Fracture barrier estimation by the edge fracture test method

Gogotsi, G. A.; Mudrik, S. P.

doi:10.1016/j.ceramint.2008.10.026

Cited by 29 publications

(27 citation statements)

References 13 publications

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“…The comparison of the present test results with those obtained earlier [4,11], has shown that, while not contradicting each other, these results only increase the amount of useful information on the behavior of glasses under the loading conditions considered. In the analysis, the results were plotted on the base diagram [12] where both the relation between the fracture resistance F R and the critical stress intensity factor K c I values (the EF base line) [5] and the relation constructed using the values of the fracture resistance F RV of specimens in edge flaking caused by indentations with a Vickers indenter [11] are presented (Fig.…”

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confidence: 48%

“…For comparison, Fig. 3 also illustrates the test results for linear-elastic fine-grained alumina (Al 2 O 3 ) ceramics, and hot-pressed silicon carbides (HP SiC) and E Kasic ® F [11]. It is seen that for glasses, the values of F R are located above the EF-base line, whereas those of F RV are located near the F K RV c -I relation.…”

mentioning

confidence: 86%

“…In the analysis, the results were plotted on the base diagram [12] where both the relation between the fracture resistance F R and the critical stress intensity factor K c I values (the EF base line) [5] and the relation constructed using the values of the fracture resistance F RV of specimens in edge flaking caused by indentations with a Vickers indenter [11] are presented (Fig. 3).…”

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confidence: 99%

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Fracture resistance of technical and optical glasses: edge flaking of specimens

Gogotsi

Mudrik

2010

Strength Mater

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We present the results of fracture resistance tests for technical and optical glasses performed by indentation flaking of the rectangular specimen edge. The features of crack propagation in these glasses are analyzed during chipping fracture caused by indentation with blunt and sharp diamond indenters. By comparative analysis of the values for resistance to edge flaking and those for fracture resistance, new data on the mechanical behavior of the above glasses in fracture are obtained. In particular, it is shown that these glasses, along with ceramic materials used to produce armor, have an enhanced resistance to the onset of fracture.Introduction. The importance of glasses in engineering and daily usage cannot be overestimated. Although glass is a very brittle and catastrophically failing material which, in many applications, is forced to withstand high mechanical loads, its ability to resist fracture has, however, received little attention in recent years. The fracture resistance of glasses is evaluated by the methods developed to test ceramics [1], since there is no standard regulating their specific behavior in fracture. Here, the IF method (Vickers indentation on a polished surface of the specimen and measurement of crack sizes near its indentation corners) is used quite often [2], however, with this method, it is in effect impossible to obtain reliable data on the actual resistance of brittle materials at critical loads [3]. To eliminate random dangerous damage to edges of glass items, facets are applied to them or they are rounded off without any estimates being made for this effect.In view of the above-said, an attempt has been undertaken to study the fracture resistance of glasses [4] using a non-traditional experimental method, such as the EF method (involving the flaking of the rectangular specimen edge [5]), which was found to be efficient in evaluating various ceramics [6, 7, et al.]. This paper presents the results of new investigations in this field, special emphasis being placed on the fracture of glasses with the variation in the stress concentration due to different indenters employed.Materials and Procedures. Silicate glasses (both technical and lead-containing ones (such as flint glass) were the main objects of this investigation, whereas heavy crown glass was the auxiliary object [8]. Specimens of these materials were manufactured in the form of rectangular beams measuring 3 4 20´mm. The specimen surfaces were initially ground, and then their faces of 4 mm in width were buffed. Five such specimens were glued together at the treated faces with the Loctite ® Super Glue (Henkel Corp., USA) to form a package whose planes were additionally ground and subsequently polished. In this way, the sufficient sharpness of rectangular specimen edges and the absence of any chip scars thereon, which are hard to remove by usual mechanical treatment of glasses, were provided.In this paper, the fracture resistance of glasses was evaluated by the SEVNB method [9], according to which the fracture of a rectangular ...

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Fracture resistance of technical and optical glasses: edge flaking of specimens

Gogotsi

Mudrik

2010

Strength Mater

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“…5). Direct proportionality (similar to the baseline) is also observed in tests with other indenters such as a Vickers indenter [18]. When plotted on the base diagram, such straight lines (which may be called proportionality lines) have a smaller slope angle than that of the baseline (Fig.…”

Section: Analysis Of Test Datamentioning

confidence: 83%

“…An attempt was made in Ref. [18] to analyze a high fracture barrier based on edge-chipping data obtained with a Vickers indenter, which causes elastic-plastic fracture of the material. In this case, however, the concept of fracture onset barrier loses its meaning.…”

Section: Analysis Of Test Datamentioning

confidence: 99%

Edge chipping resistance of ceramics: Problems of test method

Gogotsi

2013

J Adv Ceram

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An unconventional method for determining the fracture resistance of brittle materials is discussed. This method employs a conical indenter to chip the rectangular edge of the specimen. Particular features of the method are the use of small specimens and the evaluation of the resistance of materials to the nucleation, initiation and propagation of a crack. It is shown that this method is somewhat similar to the Hertzian fracture method and to the way that early man selected stones to make tools and weapons. Measured data of the fracture resistance of ceramics is presented. It is confirmed that if a ceramic material is similar to the model material of linear elastic fracture mechanics (LEFM), then those fracture resistance values are directly proportional to the critical stress intensity factors (baseline). For elastic and inelastic ceramics, R-lines characterizing the fracture resistance to crack growth are plotted. It is shown that proportionality lines (edge chipping resistance versus critical stress intensity factor) may be straight lines for ceramics with similar structure (such as Y-TZP and Mg-PSZ). The effect of rounding of the conical indenter tip (10-800 µm) on chip scar shape is indicated. Other aspects in the fracture behavior of ceramics during edge chipping are also analyzed. The advantages and disadvantages of the method are discussed. Further studies in this mechanico-physical research area are suggested.

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