Mechanical and Fracture Properties of Bamboo

2006 ◽  
Vol 312 ◽  
pp. 15-20 ◽  
Author(s):  
It Meng Low ◽  
Z.Y. Che ◽  
Bruno A. Latella ◽  
K.S. Sim
Keyword(s):  
Fracture Toughness ◽  
Mechanical Performance ◽  
Elastic Stiffness ◽  
Crack Deflection ◽  
Vickers Indentation ◽  
Fracture Properties ◽  
Depth Profiles ◽  
High Toughness ◽  
Synchrotron Radiation Diffraction ◽  
Mechanical And Fracture Properties

The microstructure, mechanical, impact and fracture properties of Australian bamboo have been investigated. The graded composition and property has been confirmed by depth-profiles obtained by synchrotron radiation diffraction and Vickers indentation. The mechanical performance of bamboo is stronly dependent on age. Results showed that young bamboo has higher strength, elastic stiffness and fracture toughness than its old counterpart. Both crack-deflection and crackbridging are the major energy dissipative processes for imparting a high toughness in bamboo.

Mapping the structure, composition and mechanical properties of bamboo

2006 ◽  
Vol 21 (8) ◽  
pp. 1969-1976 ◽  
Author(s):  
I.M. Low ◽  
Z.Y. Che ◽  
B.A. Latella
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Damage Zone ◽  
Elastic Stiffness ◽  
Indentation Creep ◽  
Interfacial Damage ◽  
Depth Profiles ◽  
High Toughness ◽  
Synchrotron Radiation Diffraction

The structure, composition, and mechanical response of Australian bamboo were investigated. The graded structure, composition, and mechanical properties were confirmed by depth profiles obtained using synchrotron radiation diffraction and Vickers indentation. The mechanical performance of bamboo was strongly dependent on age. Results indicated that young bamboo has a higher strength, elastic stiffness, and fracture toughness than its older counterpart does. In addition, the hardness of bamboo is both load dependent and time dependent as a result of an expanding interfacial damage zone and indentation creep, respectively. In addition to fiber debonding, crack deflection and crack-bridging are the major energy dissipative processes for imparting a high toughness in bamboo.

scholarly journals Thermo-mechanical characterization of shale using nanoindentation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yanbo Wang ◽  
Debora Lyn Porter ◽  
Steven E. Naleway ◽  
Pania Newell
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Elevated Temperature ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Substantial Impact ◽  
Fracture Properties ◽  
Nano Scale ◽  
Bedding Planes ◽  
Mechanical And Fracture Properties

AbstractShale can be a potential buffer for high-level radioactive nuclear wastes. To be an effective buffer while subject to waste heat, shale's mechanical response at elevated temperature must be known. Many researchers have experimentally characterized the mechanical behavior of various shales at different length scales in adiabatic conditions. However, its mechanical performance at elevated temperatures at the nano-scale remains unknown. To investigate the temperature dependency of nanomechanical properties of shale, we conducted both experimental and numerical studies. In this study, we measured mechanical and fracture properties of shale, such as hardness, elastic modulus, anisotropy, and fracture toughness from 25 °C up to 300 °C at different bedding planes. Statistical analysis of the results suggests that hardness and fracture toughness significantly increased at temperatures from 100 to 300 °C; while, temperature does not have a significant impact on elastic modulus. Data also shows that the bedding plane orientations have a substantial impact on both mechanical and fracture properties of shale at the nano-scale leading to distinct anisotropic behavior at elevated temperature below 100 °C. Additionally, we numerically investigated the mechanical performance of the shale samples at room temperature to gain an insight into its mechanical response through the thickness. Numerical results were validated against the experimental results, confirming the simulation can be used to predict shale deformation at the nano-scale or potentially be used in multi-scale simulations.

Finite Element Modeling of Microcrack Growth in Cortical Bone

2011 ◽  
Vol 78 (4) ◽  
Author(s):  
Susan Mischinski ◽  
Ani Ural
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Elastic Modulus ◽  
Crack Growth ◽  
Line Strength ◽  
Crack Deflection ◽  
Cement Line ◽  
Fracture Properties ◽  
Cement Lines ◽  
Microcrack Growth

Bone is similar to fiber-reinforced composite materials made up of distinct phases such as osteons (fiber), interstitial bone (matrix), and cement lines (matrix-fiber interface). Microstructural features including osteons and cement lines are considered to play an important role in determining the crack growth behavior in cortical bone. The aim of this study is to elucidate possible mechanisms that affect crack penetration into osteons or deflection into cement lines using fracture mechanics-based finite element modeling. Cohesive finite element simulations were performed on two-dimensional models of a single osteon surrounded by a cement line interface and interstitial bone to determine whether the crack propagated into osteons or deflected into cement lines. The simulations investigated the effect of (i) crack orientation with respect to the loading, (ii) fracture toughness and strength of the cement line, (iii) crack length, and (iv) elastic modulus and fracture properties of the osteon with respect to the interstitial bone. The results of the finite element simulations showed that low cement line strength facilitated crack deflection irrespective of the fracture toughness of the cement line. However, low cement line fracture toughness did not guarantee crack deflection if the cement line had high strength. Long cracks required lower cement line strength and fracture toughness to be deflected into cement lines compared with short cracks. The orientation of the crack affected the crack growth trajectory. Changing the fracture properties of the osteon influenced the crack propagation path whereas varying the elastic modulus of the osteon had almost no effect on crack trajectory. The findings of this study present a computational mechanics approach for evaluating microscale fracture mechanisms in bone and provide additional insight into the role of bone microstructure in controlling the microcrack growth trajectory.

Failure Behaviour of High Toughness Multi-Layer Si3N4 and Si3N4-TiN Based Laminates

2005 ◽  
Vol 290 ◽  
pp. 175-182 ◽  
Author(s):  
Gurdial Blugan ◽  
Richard Dobedoe ◽  
I. Gee ◽  
Nina Orlovskaya ◽  
Jakob Kübler
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Residual Stresses ◽  
Crack Propagation ◽  
Failure Mechanisms ◽  
High Strength ◽  
Crack Deflection ◽  
High Toughness ◽  
Energy Absorbing ◽  
Crack Bifurcation

Multi-layer laminates were produced using alternating layers of Si3N4 and Si3N4+TiN. The differences in the coefficient of thermal expansions between the alternating layers lead to residual stresses after cooling. These are compressive in the Si3N4 layers and tensile in the Si3N4+TiN layers. The existence of these stresses in the laminates effect the crack propagation behaviour during failure. Different designs of laminates were produced with external layers under compression and tension exhibiting different failure mechanisms. Facture toughness was measured by SEVNB method. In systems with external layers under compression the measured fracture toughness was up to three times that of Si3N4, i.e. up to 17 MPa m1/2. In systems with external layers under tension during failure the energy absorbing effects of crack deflection and crack bifurcation were obtained. High temperature tests were performed to determine the onset temperature for residual stresses in these laminates. Micro-laminates with compressive layers of only 30 µm thickness with high strength and fracture toughness and were manufactured.

Fracture Toughness of HVOF Sprayed WC-Co Coatings

2000 ◽  
Author(s):  
S. De Palo ◽  
M. Mohanty ◽  
H. Marc-Charles ◽  
M. Dorfman
Keyword(s):  
Fracture Toughness ◽  
Gas Turbines ◽  
Wear Behavior ◽  
Physical And Mechanical Properties ◽  
Mean Free Path ◽  
Vickers Indentation ◽  
Centrifugal Pumps ◽  
Compressor Blades ◽  
Fracture Properties ◽  
Spray Process

Abstract Tungsten carbide-cobalt coatings are extensively used to protect surfaces from wear in many types of applications, such as compressor piston rods, pump plungers, shaft sleeves on centrifugal pumps and fans, and midspans of compressor blades in gas turbines. The wear behavior in any application is strongly influenced by the basic physical and mechanical properties of such coatings. Fracture toughness as a mechanical property indicates the resistance to fracture in the presence of a sharp crack, and thus provides a measure of the intrinsic strength of the cemented carbides coatings. In this study, Vickers indentation tests have been used to quantify the in-plane fracture behavior of various WC-based coatings deposited by the High Velocity Oxy-Fuel (HVOF) spray process. The indentation cracks are analyzed in terms of standardized relations that utilize radial-median crack geometries. It is shown that the fracture properties of HVOF WC-Co coatings are anisotropic, and depend strongly on the microstructure and composition of the coatings. The crack propagation is determined by the porosity, binder mean free path, and the shape, size, and distribution of the reinforcing carbide particles. The erosion resistances of the coatings have also been discussed as a function of the fracture properties and mechanisms. It is shown, in this study, that the Vickers indentation method is a useful and convenient technique for determining the in-plane fracture toughness of HVOF sprayed WC-based coatings.

Fracture Toughness and Magnetic Properties of Sm2Co17-Based Magnets

2013 ◽  
Vol 645 ◽  
pp. 81-84 ◽  
Author(s):  
Ai Kun Li ◽  
Li Ya Li ◽  
Yuan Dong Peng ◽  
Jian Hong Yi
Keyword(s):  
Fracture Toughness ◽  
Magnetic Properties ◽  
High Performance ◽  
Maximum Energy ◽  
Crack Deflection ◽  
Toughening Mechanisms ◽  
Screw Dislocations ◽  
Yield Plateau ◽  
High Toughness ◽  
Type Magnet

We present our findings of increased fracture toughness in high performance Sm2Co17-type magnet. The new Sm(Co 0.65 Fe 0.24 Cu 0.08 Zr 0.03)7.6magnet exhibits remanence of 11.13 kGs, maximum energy of 30.2 MGOe. This magnet shows not only a superhigh fracture toughness of 5.56 MPa m 1/2 but also distinguished yielding combined with an enhanced plastic plateau of 30 % to failure. It has been found that debonding, crack deflection, crac k branching and bridging are the major toughening mechanisms for the observed high toughness and long yield plateau. Long and straight screw dislocations observed in Sm rich precipitates accelerate the debonding of Sm rich grains.

scholarly journals Thermal and Mechanical Interfacial Behaviors of Graphene Oxide-Reinforced Epoxy Composites Cured by Thermal Latent Catalyst

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1354 ◽  
Author(s):  
Shahina Riaz ◽  
Soo-Jin Park
Keyword(s):  
Thermal Stability ◽  
Fracture Toughness ◽  
Graphene Oxide ◽  
Mechanical Performance ◽  
Gradual Increase ◽  
Diglycidyl Ether ◽  
Crack Deflection ◽  
Epoxy Composites ◽  
Curing Agent ◽  
Thermal Stability Of

A series of composites was prepared from a diglycidyl ether of bisphenol A (DGEBA) with different graphene filler contents to improve their mechanical performance and thermal stability. Graphene oxide (GO) and GO modified with hexamethylene tetraamine (HMTA) were selected as reinforcing agents. As a latent cationic initiator and curing agent, N-benzylepyrizinium hexafluoroantimonate (N-BPH) was used. The effect of fillers and their contents on the mechanical properties and thermal stability of the composites were studied. Fracture toughness improved by 23% and 40%, and fracture energy was enhanced by 1.94- and 2.27-fold, for the composites containing 0.04 wt.% GO and HMTA-GO, respectively. The gradual increase in fracture toughness at higher filler contents was attributed to both crack deflection and pinning mechanisms. Maximum thermal stability in the composites was achieved by using up to 0.1 wt.% graphene fillers.

scholarly journals C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

2020 ◽  
Author(s):  
Heng Luo ◽  
Chen Li ◽  
Lianwen Deng ◽  
Yang Li ◽  
Peng Xiao ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Crack Deflection ◽  
Crack Branching ◽  
Hot Press ◽  
Pull Out ◽  
Si3n4 Ceramics

In-situ grown C0.3N0.7Ti and SiC, which derived from non-oxide additives Ti3SiC2, are proposed to densify silicon nitride (Si3N4) ceramics with enhanced mechanical performance. Remarkable increase of density from 79.20% to 95.48% could be achieved for Si3N4 ceramics with 5vol% Ti3SiC2. The capillarity of decomposed Si from Ti3SiC2, and in-situ reaction between nonstoichiometric TiCx and Si3N4 were believed to be responsible for densification of Si3N4 ceramics. An obvious enhancement of flexural strength and fracture toughness for Ti3SiC2 doped Si3N4 ceramics was observed. The maximum flexural strength of 795 MPa for Si3N4 composites with 5vol% Ti3SiC2 and maximum fracture toughness of 6.97 MPa.m1/2 for Si3N4 composites with 20vol% Ti3SiC2 are achieved when mixed powders are hot-press sintered at 1700℃. Pull out of elongated Si3N4 grains, crack bridging, crack branching and crack deflection were demonstrated to dominate enhance fracture toughness of Si3N4 composites.

scholarly journals Mechanical and Fracture Properties of Fly Ash Geopolymer Concrete Addictive with Calcium Aluminate Cement

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2982 ◽  
Author(s):  
Yamin Wang ◽  
Shaowei Hu ◽  
Zhen He
Keyword(s):  
Fracture Toughness ◽  
Fly Ash ◽  
Fracture Energy ◽  
Calcium Aluminate ◽  
Peak Load ◽  
Calcium Aluminate Cement ◽  
Geopolymer Concrete ◽  
Fracture Properties ◽  
Mechanical And Fracture Properties ◽  
Aluminate Cement

In this paper, the mechanical and fracture properties of fly ash geopolymer concrete (FAGC) mixed with calcium aluminate cement (CAC) were explored. Fly ash was partially replaced by CAC with 2.5%, 5% and 7.5%. The results exhibit that the mechanical and fracture behaviors of FAGC are significantly influenced by CAC content. Based on the formation of more aluminum-rich gels, C-(A)-S-H and C-S-H gels, with the increase of CAC content, the compressive strength, splitting tensile strength and elastic modulus improved. Meanwhile, the peak load and effective fracture toughness show a monotone increasing trend. In addition, because C-S-H gels absorbed more energy, the fracture energy of FAGC increases. The maximal peak load, double-K fracture toughness and fracture energy reached up to1.79 kN, 4.27 MPam0.5, 10.1 MPam0.5 and 85.8 N/m with CAC content of 7.5%, respectively.

Micromechanics Measurements Applied to Integrated Circuit Microelectronics

1997 ◽  
Vol 473 ◽  
Author(s):  
David R. Clarke
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Fracture Resistance ◽  
Interface Fracture ◽  
New Techniques ◽  
Fracture Properties ◽  
Engineered Structures ◽  
Mechanical And Fracture Properties ◽  
Interconnect Lines ◽  
Metallic Interconnect

ABSTRACTAs in other engineered structures, fracture occasionally occurs in integrated microelectronic circuits. Fracture can take a number of forms including voiding of metallic interconnect lines, decohesion of interfaces, and stress-induced microcracking of thin films. The characteristic feature that distinguishes such fracture phenomena from similar behaviors in other engineered structures is the length scales involved, typically micron and sub-micron. This length scale necessitates new techniques for measuring mechanical and fracture properties. In this work, we describe non-contact optical techniques for probing strains and a microscopic “decohesion” test for measuring interface fracture resistance in integrated circuits.

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