scholarly journals A method to determine fracture toughness using cube-corner indentation

2010 ◽  
Vol 62 (4) ◽  
pp. 199-201 ◽  
Author(s):  
Taihua Zhang ◽  
Yihui Feng ◽  
Rong Yang ◽  
Peng Jiang
Keyword(s):  
Fracture Toughness ◽  
Cube Corner ◽  
Determine Fracture Toughness

Characterizing Anisotropic Fracture Toughness of Shale Using Nanoindentation

2021 ◽  
pp. 1-13
Author(s):  
Erica Esatyana ◽  
Mehdi Alipour ◽  
A. Sakhaee-Pour
Keyword(s):  
Fracture Toughness ◽  
Conceptual Model ◽  
Effective Medium Theory ◽  
Fused Silica ◽  
Small Samples ◽  
Medium Theory ◽  
Anisotropic Fracture ◽  
Cube Corner ◽  
Induced Fractures ◽  
Anisotropic Fracture Toughness

Summary Shale, which has pores as small as 10 nm, is economically viable for hydrocarbon recovery when it is fractured. Although the fracture toughness dictates the required energy for the improvement, the existing techniques are not suitable for characterization at scales smaller than 1 cm. Developing practical methods for characterization is crucial because fractures can contribute to an accessible pore volume at different scales. This study proposes a conceptual model to characterize the anisotropic fracture toughness of shale using nanoindentations on a sub-1-cm scale. The conceptual model reveals the complexities of characterizing shales and explains why induced fractures differ from those observed in more-homogeneous media, such as fused silica. Samples from the Wolfcamp Formation were tested using Berkovich and cube-corner tips, and the interpreted fracture toughness values are promising. The conceptual model is the first application of the effective-medium theory for fracture toughness characterization using nanoindentation. In addition, it can quantify fracture toughness variations when using small samples, such as drill cuttings.

A Method to Determine Fracture Toughness Using Berkovich Indenter for Bulk Materials

2013 ◽  
Vol 331 ◽  
pp. 456-460
Author(s):  
Min He ◽  
Duan Hu Shi ◽  
Feng Yang ◽  
Ning Zhang ◽  
Hua Feng Guo
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Penetration Depth ◽  
Effective Elastic Modulus ◽  
Berkovich Indenter ◽  
Bulk Materials ◽  
Ductile Materials ◽  
Penetration Depths ◽  
Determine Fracture Toughness

An indentation approach with Berkovich indenter is proposed to determine fracture toughness for ductile materials. With decrease of effective elastic modulus, an approximate linear relationship between logarithmic plastic penetration depth and logarithmic effective elastic modulus, and a quadratic polynomial relationship between the plastic penetration depths and penetration loads are exhibited by indentation investigation with Berkovich indenter. The damage constructive equation of effective elastic modulus is proposed to determine the critical effective elastic modulus at the fracture point, which is the key problem to calculate the indentation energy to fracture. The critical plastic penetration depth is identified after the critical effective elastic modulus can be predicted by conventional mechanical properties. The fracture toughness is calculated according to the equation of penetration load, plastic penetration depth and the critical plastic penetration depth.

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 Evaluation of fracture toughness of small volumes by means of cube-corner nanoindentation

2012 ◽  
Vol 66 (9) ◽  
pp. 670-673 ◽  
Author(s):  
N. Cuadrado ◽  
D. Casellas ◽  
M. Anglada ◽  
E. Jiménez-Piqué
Keyword(s):  
Fracture Toughness ◽  
Cube Corner

The use of compact specimens to determine fracture toughness anisotropy of Ti–6Al–4V additively manufactured for repair

2021 ◽  
pp. 141779
Author(s):  
Sammy A. Ojo ◽  
Sulochana Shrestha ◽  
Joseph El Rassi ◽  
Ragav P. Panakarajupally ◽  
K. Manigandan ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Toughness Anisotropy ◽  
Determine Fracture Toughness

Sharp probes of varying acuity: Instrumented indentation and fracture behavior

2004 ◽  
Vol 19 (1) ◽  
pp. 165-175 ◽  
Author(s):  
Dylan J. Morris ◽  
Sasha B. Myers ◽  
Robert F. Cook
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Instrumented Indentation ◽  
Cube Corner ◽  
Load Displacement ◽  
Estimation Models

The fracture and instrumented indentation behavior of a range of materials subjected to indentation by four sharp probes varying in acuity from the Berkovich to the cube-corner was studied. Quantities derived from load, displacement, and continuous stiffness measurements were evaluated for their ability to detect “pop-in”—sudden displacement excursions associated with fracture. It was found that gross unloading character was sensitive to the presence of fracture, even when no pop-in was detected. This may be useful in the development of fracture toughness estimation models that do not rely on the imaging of cracks.

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