Fracture toughness of two-dimensional cellular material with periodic microstructure

2007 ◽  
Vol 146 (4) ◽  
pp. 279-290 ◽  
Author(s):  
Fabian Lipperman ◽  
Michael Ryvkin ◽  
Moshe B. Fuchs
Keyword(s):  
Fracture Toughness ◽  
Cellular Material ◽  
Two Dimensional ◽  
Periodic Microstructure

scholarly journals Fracture toughness of one- and two-dimensional nanoreinforced cement via scratch testing

2021 ◽  
Vol 379 (2203) ◽  
pp. 20200288 ◽  
Author(s):  
Ange-Therese Akono
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Cement Industry ◽  
Vertical Force ◽  
Two Dimensional ◽  
Scratch Testing ◽  
Helical Carbon Nanotubes ◽  
Reinforced Cement ◽  
Carbon Based Nanomaterials ◽  
Carbon Based

Cement is the most widely consumed material globally, with the cement industry accounting for 8% of human-caused greenhouse gas emissions. Aiming for cement composites with a reduced carbon footprint, this study investigates the potential of nanomaterials to improve mechanical characteristics. An important question is to increase the fraction of carbon-based nanomaterials within cement matrices while controlling the microstructure and enhancing the mechanical performance. Specifically, this study investigates the fracture response of Portland cement reinforced with one- and two-dimensional carbon-based nanomaterials, such as carbon nanofibres, multiwalled carbon nanotubes, helical carbon nanotubes and graphene oxide nanoplatelets. Novel processing routes are shown to incorporate 0.1–0.5 wt% of nanomaterials into cement using a quadratic distribution of ultrasonic energy. Scratch testing is used to probe the fracture response by pushing a sphero-conical probe against the surface of the material under a linearly increasing vertical force. Fracture toughness is then computed using a nonlinear fracture mechanics model. Nanomaterials are shown to bridge nanoscale air voids, leading to pore refinement, and a decrease in the porosity and the water absorption. An improvement in fracture toughness is observed in cement nanocomposites, with a positive correlation between the fracture toughness and the mass fraction of nanofiller for graphene-reinforced cement. Moreover, for graphene-reinforced cement, the fracture toughness values are in the range of 0.701 to 0.717 MPa m . Thus, this study illustrates the potential of nanomaterials to toughen cement while improving the microstructure and water resistance properties. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

scholarly journals 3D–2D analysis of a thin film with periodic microstructure

2006 ◽  
Vol 136 (2) ◽  
pp. 223-243 ◽  
Author(s):  
Jean-François Babadjian ◽  
Margarida Baía
Keyword(s):  
Thin Film ◽  
Convergence Analysis ◽  
Dimensional Reduction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Analysis Techniques ◽  
Periodic Microstructure ◽  
Γ Convergence

In this article we study the behaviour of a heterogeneous thin film whose microstructure oscillates on a scale that is comparable to that of the thickness of the domain. The argument is based on a three-dimensional–two-dimensional reduction through a Γ-convergence analysis, techniques of two-scale convergence and a decoupling procedure between the oscillating variable and the in-plane variable.

Fracture Properties of an Anisotropic Biological Cellular Material - Apple Flesh

1990 ◽  
Vol 207 ◽  
Author(s):  
Ali A. Khan ◽  
Julian F. V. Vincent
Keyword(s):  
Fracture Toughness ◽  
Marked Effect ◽  
Crack Opening ◽  
Cellular Material ◽  
Taste Panel ◽  
Slow Freezing ◽  
Intercellular Spaces ◽  
Fracture Properties ◽  
Parenchyma Cells ◽  
Fracture Tests

AbstractThe texture of apple flesh is important in assessing its eating qualities. The texture in turn is related to the structure of the parenchyma. The parenchyma cells of the fruit are arranged in radial quasi-columnar form with radial spaces in between. This anisotropy has a marked effect on the fracture properties such that it is much easier to drive a crack between the columns (radially) than to drive it across them (tangentially). The fracture tests used were simple crack-opening tests under tension or using a wedge. This difference was also detected by a taste panel. The radial spaces ease the passage of cracks travelling along them, and act as crack stoppers for cracks travelling at right angles to them. They also allow the cells to deform more in one orientation more giving the structure ductility and making the apple tougher in that orientation. It is possible to increase this effect by controlled damage such as slow freezing which causes the intercellular spaces to expand increasing the crack-stopping mechanisms and increasing the ductility, therefore increasing the fracture toughness. Toughness first increases, then decreases with increasing damage. This effect can be mimicked with brittle paper: fracture toughness of tracing paper initially increases if holes are punched randomly in it.

scholarly journals 2013 Koiter Medal Paper: Crack-Tip Fields and Toughness of Two-Dimensional Elastoplastic Lattices

2015 ◽  
Vol 82 (9) ◽  
Author(s):  
H. C. Tankasala ◽  
V. S. Deshpande ◽  
N. A. Fleck
Keyword(s):  
Fracture Toughness ◽  
Cell Wall ◽  
Relative Density ◽  
Tensile Strain ◽  
Scaling Laws ◽  
Failure Strain ◽  
Crack Tip ◽  
Wall Material ◽  
Two Dimensional ◽  
Crack Tip Fields

The dependence of the fracture toughness of two-dimensional (2D) elastoplastic lattices upon relative density and ductility of cell wall material is obtained for four topologies: the triangular lattice, kagome lattice, diamond lattice, and the hexagonal lattice. Crack-tip fields are explored, including the plastic zone size and crack opening displacement. The cell walls are treated as beams, with a material response given by the Ramberg–Osgood law. There is choice in the criterion for crack advance, and two extremes are considered: (i) the maximum local tensile strain (LTS) anywhere in the lattice attains the failure strain or (ii) the average tensile strain (ATS) across the cell wall attains the failure strain (which can be identified with the necking strain). The dependence of macroscopic fracture toughness upon failure strain, strain hardening exponent, and relative density is obtained for each lattice, and scaling laws are derived. The role of imperfections in degrading the fracture toughness is assessed by random movement of the nodes. The paper provides a strategy for obtaining lattices of high toughness at low density, thereby filling gaps in material property space.

Two-Dimensional Mapping of Crack-Face Bridging Stresses in Alumina Using Synchrotron Micro X-Ray Beam

2008 ◽  
Vol 571-572 ◽  
pp. 243-248 ◽  
Author(s):  
Yoshihisa Sakaida ◽  
Shotaro Mori
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Stress Field ◽  
Crack Tip ◽  
The Other ◽  
Two Dimensional ◽  
Crack Face ◽  
X Ray ◽  
Bridging Stresses ◽  
Compressive Residual Stresses

In order to understand an effect of crack-face bridging stress field of alumina ceramics on its fracture toughness, local residual stress distribution due to crack face grain bridging behind the crack tip was measured using synchrotron x-ray beam at SPring-8 in Japan. The SEPB (Single Edge Precracked Beam) specimens of two types of polycrystalline Al2O3 were used for stress measurement; one was pressureless sintered Al2O3 (AL1) and the other was hot-press sintered Al2O3 (TAL). Pop-in precracks were introduced by bridge-indentation method. Before residual stress mapping, the SEPB specimens were unloaded from a constant applied load to zero using four points bending device. Two-dimensional residual stress field was mapped by scanning a micro X-ray beam of 50×50 μm2 with the scanning interval of 12.5 or 25 μm. As a result, in the case of AL1 having conventional fracture toughness and strength, the compressive residual stresses due to crack-face bridging were only observed in the close vicinity of crack tip. On the other hand, in the case of TAL having higher fracture toughness and strength, the compressive residual stresses were widely distributed behind the crack tip. Larger compressive stress was locally generated along the crack path at interlocked grains. The compressive bridging stresses distributed behind the crack tip were found to enlarge with a decrease in the crack opening displacement against a constant applied stress intensity factor, Kapp. It was concluded that the difference in residual stress fields behind crack tip was attributed to the differences in its microstructure and microcrack propagation behavior, such as deflections and interlocked grains.

Effects of Pyrolysis Temperatures on the Microstructure and Mechanical Properties of 2D-Cf/Si-O-C Composites

2008 ◽  
Vol 368-372 ◽  
pp. 1022-1024 ◽  
Author(s):  
Jing Yu Liu ◽  
Ke Jian ◽  
Zhao Hui Chen ◽  
Qing Song Ma ◽  
Song Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Pyrolysis Temperature ◽  
Silicon Oxycarbide ◽  
Silicone Resin ◽  
Two Dimensional ◽  
Microstructure And Mechanical Properties ◽  
Carbon Fiber Cloth

Two-dimensional carbon fiber cloth reinforced silicon oxycarbide (2D-Cf/Si-O-C) composites were fabricated with silicone resin (SR) as precursors, ethanol as solvent and SiC as inert fillers by precursor infiltration pyrolysis (PIP). Effects of the pyrolysis temperatures in the first cycle and the last but third cycle on the microstructure and mechanical properties of 2D-Cf/Si-O-C composites were investigated. The results showed that, when the pyrolysis temperature of the first cycle was 1200°C, 2D-Cf/Si-O-C composites exhibited good mechanical properties, which can be attributed to the better fiber/matrix interfacial bonding. When the pyrolysis temperature of the last but third cycle was 1400°C, the mechanical properties of 2D Cf/Si-O-C composites were further enhanced. The flexural strength and fracture toughness of the composites reached 263.9MPa and 12.8 MPa·m1/2, respectively.

Synthesis of Two-Dimensional Carbon and Carbon-Metal Nanocomposites Using a Natural Cellular Material as the Carbon Precursor

2010 ◽  
Vol 2010 (27) ◽  
pp. 4367-4373 ◽  
Author(s):  
Fengbin Li ◽  
Ling Li ◽  
Xingzhi Liao ◽  
Ling Tong ◽  
Zhiquan Chen ◽  
...  
Keyword(s):  
Cellular Material ◽  
Carbon Precursor ◽  
Two Dimensional ◽  
Metal Nanocomposites
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