Fracture mechanics approach to evaluation of strength in sintered silicon nitride

Hoshide, Toshihiko; Furuya, Hidemine; Nagase, Y.; Yamada, Toshiro

doi:10.1007/bf01140630

Cited by 38 publications

(16 citation statements)

References 14 publications

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“…Since natural flaws have various configurations, it is convenient to introduce the concept of an equivalent crack length l [7]. For a large n, (ai) q >> (as) q can be reasonably accepted for the long life fatigue regime.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, some applications of indentation cracks were also made under cyclic loading [2,3]. The flaw size effect has been suggested to appear in the strength tests by several investigators [6][7][8]. On the other hand, the effect of residual stress due to plastic deformation caused by indentation should be taken into account in the strength tests using indented specimens [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Fatigue crack growth from indentation flaw in ceramics

1988

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The indentation crack has been used as a model of surface flaw in the strength tests of ceramics. In evaluation of such strength properties, some attention should be paid to the residual stress effect due to indentation. In this study, fatigue crack growth behavior from indentation flaws was investigated in sintered silicon nitride and alumina. In both materials, a V-shaped behavior was observed in the relation between the maximum stress intensity factor and the crack growth rate. The indentation crack was analyzed using fracture mechanics procedure to take account of the residual component. On the basis of the analysis, an effective stress intensity factor for crack growth was successfully evaluated. The growth rate was correlated to the effective stress intensity factor, and the relation was found to be approximated by a power law equation. The fatigue crack growth property obtained as above was applied to an estimation of fatigue life of specimens without artificial flaws. The flaw size effect was also discussed based on the result,

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth from indentation flaw in ceramics

1988

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“…It has been reported, however, that the fracture originating from a smaller flaw in ceramics occurs at a lower stress than that predicted on the basis of the planestrain fracture toughness criterion [1][2][3][4]. This suggests that it is dangerous to estimate the strength of a ceramic component by using fracture mechanics parameters obtained for large cracks.…”

Section: Introductionmentioning

confidence: 98%

Dependence of Strength on Size of Flaw Dominating Fracture in Ceramics

Hoshide¹,

Masuda²

1995

Journal of the Society of Materials Science, Japan

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Bending tests using a silicon nitride and an alumina were carried out under 4-point bending to clarify the relation between the strength and the size of flaw observed at a fracture origin. When the fracture originated from a smaller flaw, the strength was confirmed to be lower than that expected from the fracture toughness criterion. A convenient procedure using the mean strength and the fracture toughness was proposed to estimate the strength degradation depending on flaw size. A new model was also developed assuming the stable cracking caused by the separation per one grain ahead of a flaw prior to the final unstable fracture. A Monte Carlo simulation based on the proposed model was made to explain the anomalous behavior of small flaw. The relation of strength vs. crack length simulated by taking account of grain-size distribution showed good agreement with the experimental result. The lower bound in scatter of strength depending on flaw-size was suggested to be estimated by using the size of the largest grain expected in a material.

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“…It is reported [5,9,10,[24][25][26][27][28] that fracture originating from a small flaw of size a in ceramics occurs at a lower stress than the estimated strength of f=KC/l: l is an equivalent crack length defined as l=aM2o [5]. The multiplication factor Mo for Kestimation is determined by a crack geometry and/or a loading mode [ex.…”

Section: Specific Crack Lengthmentioning

confidence: 99%

“…A database on the aforementioned mechanical properties of commercial ceramics was constructed using cataloged data from the databook [3] as well as some data of several ceramics which have been published by the author et al [5][6][7][8][9][10]. The database was compiled in a format of MS-Excel (the registered trademark of Microsoft Corporation) work-sheet so that interrelations among mechanical properties could be analyzed on a personal computer.…”

Section: Construction Of Databasementioning

confidence: 99%

Interrelation Analyses of Mechanical Properties in Commercial Ceramics Using Cataloged Data

Hoshide

1998

Journal of the Society of Materials Science, Japan

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Under conditions specified in this work, mechanical properties of commercial alumina, silicon carbide, silicon nitride and zirconia ceramics were selected from published manufacturers' catalogs. Numerical data of the selected properties for materials of 254 kinds in total were finally compiled in a computer-readable database. Interrelations among these properties were analyzed by using the database, and analyzed results were discussed. The selected properties of Young's modulus, linear thermal expansion coefficient, bending strength, Vickers hardness and fracture toughness were correlated with an apparent porosity derived from the theoretical and bulk density. Relationships of the selected properties to the porosity were fitted to exponential functions, and a good fitness was confirmed in most of the cases with a few exceptions. In general, every mechanical property tended to decrease with increasing the porosity. Although the hardness variation with respect to the bending strength was expressed by a proportional relationship for alumina and silicon carbide, a power relation was more adequate for silicon nitride and zirconia. The relation between the fracture toughness and the bending strength was fitted to a power function. In this case, a good fitness was identified for silicon carbide and zirconia, though a poor correlation was found for alumina and silicon carbide. A specific crack length, which was used to modify a fracture mechanics criterion for small cracks, was well correlated with the bending strength by a power function.

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Fracture mechanics approach to evaluation of strength in sintered silicon nitride

Cited by 38 publications

References 14 publications

Fatigue crack growth from indentation flaw in ceramics

Fatigue crack growth from indentation flaw in ceramics

Dependence of Strength on Size of Flaw Dominating Fracture in Ceramics

Interrelation Analyses of Mechanical Properties in Commercial Ceramics Using Cataloged Data

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