Anisotropic Fracture Toughness of Bulk GaN

2017 ◽  
Vol 255 (5) ◽  
pp. 1700515 ◽  
Author(s):  
Yutian Cheng ◽  
Duanjun Cai ◽  
Hui Wang ◽  
Jiejun Wu ◽  
Xiangshun Liu ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Anisotropic Fracture ◽  
Bulk Gan ◽  
Anisotropic Fracture Toughness

Crack forbidden area in the anisotropic fracture toughness medium

2018 ◽  
Vol 22 ◽  
pp. 172-175 ◽  
Author(s):  
Yue Gao ◽  
Zhanli Liu ◽  
Tao Wang ◽  
Qinglei Zeng ◽  
Xiang Li ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Anisotropic Fracture ◽  
Anisotropic 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.

XFEM modeling for curved fracture in the anisotropic fracture toughness medium

2018 ◽  
Vol 63 (5) ◽  
pp. 869-883 ◽  
Author(s):  
Yue Gao ◽  
Zhanli Liu ◽  
Tao Wang ◽  
Qinglei Zeng ◽  
Xiang Li ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Anisotropic Fracture ◽  
Anisotropic Fracture Toughness

A method to determine site-specific, anisotropic fracture toughness in biological materials

2012 ◽  
Vol 66 (8) ◽  
pp. 515-518 ◽  
Author(s):  
Sabine Bechtle ◽  
Hüseyin Özcoban ◽  
Ezgi D. Yilmaz ◽  
Theo Fett ◽  
Gabriele Rizzi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Biological Materials ◽  
Site Specific ◽  
Anisotropic Fracture ◽  
Anisotropic Fracture Toughness

Theoretical and numerical prediction of crack path in the material with anisotropic fracture toughness

2017 ◽  
Vol 180 ◽  
pp. 330-347 ◽  
Author(s):  
Yue Gao ◽  
Zhanli Liu ◽  
Qinglei Zeng ◽  
Tao Wang ◽  
Zhuo Zhuang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Path ◽  
Numerical Prediction ◽  
Anisotropic Fracture ◽  
Anisotropic Fracture Toughness

Anisotropic Fracture Toughness Effects on Failure Modes of Piping

1991 ◽  
Vol 113 (2) ◽  
pp. 154-158 ◽  
Author(s):  
G. M. Wilkowski
Keyword(s):  
Fracture Toughness ◽  
Failure Modes ◽  
Axial Direction ◽  
Combined Loading ◽  
Anisotropic Fracture ◽  
Circumferential Crack ◽  
Growth Plane ◽  
Bending Loads ◽  
Anisotropic Fracture Toughness ◽  
Leak Before Break

This paper summarizes various cases where anisotropic fracture toughness properties caused the failure mode to change during ductile fracture experiments on piping. It is noted that in particular for carbon steel piping, the anisotropy can cause an initial circumferential crack to propagate in a helical or even axial direction, even though there are only applied bending loads. This has implications that under combined loading, such pipes may have lower longitudinal stresses at failure than may be calculated by a leak-before-break analysis that only considers the longitudinal stresses and the toughness in the circumferential crack growth plane.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

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