Review and evaluation of the double-torsion technique for fracture toughness and fatigue testing of brittle materials

1987 ◽  
Vol 27 (1) ◽  
pp. 14-22 ◽  
Author(s):  
R. B. Tait ◽  
P. R. Fry ◽  
G. G. Garrett
Keyword(s):  
Fracture Toughness ◽  
Fatigue Testing ◽  
Brittle Materials ◽  
Double Torsion

scholarly journals On the Use of Approximation Methods for Microcrack Shielding Problems

1992 ◽  
Vol 59 (3) ◽  
pp. 497-501 ◽  
Author(s):  
H. Cai ◽  
K. T. Faber
Keyword(s):  
Fracture Toughness ◽  
Numerical Solution ◽  
Experimental Evidence ◽  
Discrete Model ◽  
Brittle Materials ◽  
Approximation Methods ◽  
Exact Formulation

There is experimental evidence that stress-induced microcracking near a macrocrack tip enhances the fracture toughness of brittle materials. In considering the interaction of the macrocrack with multiple microcracks using a discrete model, it is essential to use approximation methods in order to keep the amount of the computation to a tractable level. However, when crack distances are small, the results of the approximation methods can be significantly different from the numerical solution based upon the exact formulation. The results obtained by these approximation methods will be compared with the numerical solution to show the applicability ranges in which the errors are acceptably small. The use of results obtained by the approximation methods outside applicability ranges in literature is shown to lead to incorrect conclusions concerning microcrack shielding.

scholarly journals A coupled FFM model to interpret fracture toughness values for brittle materials

2016 ◽  
Vol 2 ◽  
pp. 1983-1990
Author(s):  
Donato Firrao ◽  
Paolo Matteis ◽  
Alberto Sapora ◽  
Pietro Cornetti ◽  
Alberto Carpinteri
Keyword(s):  
Fracture Toughness ◽  
Brittle Materials

Fracture toughness and absorbed energy measurements in impact tests on brittle materials

1973 ◽  
Vol 8 (7) ◽  
pp. 949-956 ◽  
Author(s):  
G. P. Marshall ◽  
J. G. Williams ◽  
C. E. Turner
Keyword(s):  
Fracture Toughness ◽  
Brittle Materials ◽  
Absorbed Energy ◽  
Impact Tests

scholarly journals Cracking During Nanoindentation and its Use in the Measurement of Fracture Toughness

1994 ◽  
Vol 356 ◽  
Author(s):  
D. S. Harding ◽  
W. C. Oliver ◽  
G. M. Pharr
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Small Volume ◽  
Brittle Materials ◽  
Empirical Method ◽  
Berkovich Indenter ◽  
Empirical Constant ◽  
Cube Corner ◽  
Semi Empirical ◽  
Radial Cracks

AbstractResults of an investigation aimed at developing a technique by which the fracture toughness of a thin film or small volume can be determined in nanoindentation experiments are reported. The method is based on the radial cracking which occurs when brittle materials are deformed by a sharp indenter such as a Vickers or Berkovich diamond. In microindentation experiments, the lengths of radial cracks have been found to correlate reasonably well with fracture toughness, and a simple semi-empirical method has been developed to compute the toughness from the crack lengths. However, a problem is encountered in extending this method into the nanoindentation regime with the standard Berkovich indenter in that there are well defined loads, called cracking thresholds, below which indentation cracking does not occur in most brittle materials. We have recently found that the problems imposed by the cracking threshold can be largely overcome by using an indenter with the geometry of the corner of a cube. For the cube-corner indenter, cracking thresholds in most brittle materials are as small as 1 mN (∼ 0.1 grams). In addition, the simple, well-developed relationship between toughness and crack length used for the Vickers indenter in the microindentation regime can be used for the cube-corner indenter in the nanoindentation regime provided a different empirical constant is used.

scholarly journals Measurement of dynamic fracture toughness by double torsion testing

2018 ◽  
Vol 5 (2) ◽  
pp. 17-00529-17-00529 ◽  
Author(s):  
Tadaharu ADACHI ◽  
Zoltan MAJOR ◽  
Kenji FUJII ◽  
Kohei MIKUMA ◽  
Markus Karamoy UMBOH ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Dynamic Fracture Toughness ◽  
Torsion Testing ◽  
Double Torsion

Determination of fracture toughness and fracture energy of brittle materials under impact wedging

1996 ◽  
Vol 37 (4) ◽  
pp. 586-594 ◽  
Author(s):  
A. S. Eremenko ◽  
S. A. Novikov ◽  
V. A. Sinitsyn ◽  
V. A. Pushkov ◽  
M. M. Yakupov
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Brittle Materials

Engineering Properties and Performance of Dental Crowns

2005 ◽  
Vol 219 (4) ◽  
pp. 245-255 ◽  
Author(s):  
C A Mitchell ◽  
J F Orr
Keyword(s):  
Fracture Toughness ◽  
Fatigue Testing ◽  
Thin Layers ◽  
Engineering Properties ◽  
Luting Cements ◽  
Tooth Structure ◽  
Chevron Notch ◽  
Dental Crowns ◽  
Luting Cement

Dental crowns are used to replace damaged natural crowns of teeth and are fixed to prepared teeth with luting cements, which should provide an adhesive bond to the tooth structure giving reliable retention and minimal microleakage. Mechanical testing of crowns in vitro gives failure load distributions that are well described by Weibull models, comparing probabilities of survival and reliability. Fatigue testing of crowns is time consuming, but regression analysis to interpolate functions through data points quoting probability limits or applying Weibull analysis is achievable. A complementary approach is to conduct materials tests with appropriate interfacial geometries. Luting cements are used in thin layers of 40–150 um. Contraction during polymerization is restrained by adhesion to substrates, allowing little relaxation of stresses. Conventional and resin-modified glass ionomer cements create thin zones of interaction with dentine and fail cohesively. The chevron notch short rod technique has been used to measure fracture toughness and rank cements. A development of this method, using chevron notch short bar specimens, permitted fracture toughness to be determined for luting cement-dentine substrate interfaces. Representative fracture experiments need to be developed to apply mixed mode conditions. The basic challenge to predict long-term performance from short-term laboratory tests remains.

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