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Kolhe, R.; Chen, Hui; Zehnder, Alan T.

doi:10.1023/a:1007451005263

Cited by 16 publications

(5 citation statements)

References 8 publications

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“…(1)), the thickness (gap) of the chevron notch, caused by the broadness of the FIB ion beam, is not taken into consideration. Kolhe et al 43) have evaluated the allowable The values of t C for the microbeam specimens tested in the present study were between 0.17 and 0.27 μm. We confirm that the chevron-notch thickness of any of the tested microbeam specimens was kept below 0.15 μm by the usage of the weakest Ga + ion beam and is smaller than the allowable thickness.…”

Section: Validity Of the Fracture Toughness Valuesmentioning

confidence: 86%

Fracture Toughness of the Fe–Zn Intermetallic Compounds Measured by Bend Testing of Chevron-Notched Single-Crystal Microbeams

et al. 2018

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Section: Validity Of the Fracture Toughness Valuesmentioning

confidence: 86%

Fracture Toughness of the Fe–Zn Intermetallic Compounds Measured by Bend Testing of Chevron-Notched Single-Crystal Microbeams

et al. 2018

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“…It was concluded that the principal factor was lack of stiffness of the testing machine load train. Kolhe et al 8 have shown through an FEA study that wide notches lead to greater crack instability when using this maximum required force technique. More recently, in the development of a silicon nitride fracture toughness reference material (NIST SRM 2100, the National Institute for Standards and Technology standard reference material; 9 see below) it has been shown that the results from CNB tests conducted properly are numerically indistinguishable from SEPB and SCF results.…”

Section: Chevron Notch Beam Methods (Cnb)mentioning

confidence: 97%

Fracture toughness testing for advanced technical ceramics: internationally agreed good practice

Morrell¹

2006

Advances in Applied Ceramics

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The development of robust methods for determining fracture toughness and for interlaboratory assessment of results is discussed with respect to procedural standardisation. Acceptable methods are based on meeting several criteria, including ease and cost-effectiveness of testpiece manufacture, the method of introducing a sharp precrack and the acceptability of appropriate fracture toughness analysis. The four simplest methods meeting these criteria are reviewed in detail, together with information on their reproducibility gathered during international round robin exercises. Not all these methods are effective on all materials, and users need to be aware of their limitations. Details of calibration equations and some experimental nuances are given.

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“…1). Calculations use a general, quadratic brick (C8D20) finite element; however, middle nodes of elements associated with the crack front are shifted to a quarter-element size towards the crack front [56][57][58]. The mesh and element size are optimized in order to calculate converged values of system compliances for each simulation.…”

Section: Compliance Calibrationmentioning

confidence: 99%

“…In the presence of a support, the uncracked chevron faces of the support and the cantilever are rigidly tied, while a fixed-displacement boundary condition is applied on the support face opposite the chevron notch. In modelling, the thickness of the chevron notch was implicitly assumed to be zero; thus, possible effects arising from a finite notch thickness [58] are not accounted for.…”

Section: Compliance Calibrationmentioning

confidence: 99%

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

et al. 2015

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We show that chevron-notched samples offer an attractive approach to the measurement of fracture toughness in micron-scale samples of brittle materials and use the method to characterize quartz and nanocrystalline alumina. Focused ion beam milling is used to carve bend bars of rectangular cross-section a few micrometres wide and containing a notch with a triangular ligament. Load-controlled testing is conducted using a nanoindentation apparatus. If the notch is appropriately machined, cracks nucleate and propagate in a stable fashion before becoming unstable. Sample dimensions are measured using a scanning electron microscope, and are used as input in finite element simulations of the bars' elastic deformation for various crack lengths. The calculated compliance calibration curve and the measured peak load then give the local fracture toughness of the material. Advantages of the method include a low sensitivity to environmental subcritical crack growth, and the fact that it measures toughness at the tip of a sharp crack situated in material unaffected by ion-milling. The approach is demonstrated on two materials, namely, monolithic fused quartz and nanocrystalline alumina Nextele 610 fibres; results for the latter give the intrinsic grain boundary toughness of alumina, free of grain bridging effects.

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Untitled

Cited by 16 publications

References 8 publications

Fracture Toughness of the Fe–Zn Intermetallic Compounds Measured by Bend Testing of Chevron-Notched Single-Crystal Microbeams

Fracture Toughness of the Fe–Zn Intermetallic Compounds Measured by Bend Testing of Chevron-Notched Single-Crystal Microbeams

Fracture toughness testing for advanced technical ceramics: internationally agreed good practice

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

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