scholarly journals The ideal strength of two-dimensional stanene may reach or exceed the Griffith strength estimate

Nanoscale ◽  
2017 ◽  
Vol 9 (21) ◽  
pp. 7055-7062 ◽  
Author(s):  
Zhe Shi ◽  
Chandra Veer Singh
Keyword(s):  
Two Dimensional ◽  
Ideal Strength ◽  
The Ideal

scholarly journals Composite hollow truss with multiple vierendeel panels

2013 ◽  
Vol 66 (4) ◽  
pp. 431-438
Author(s):  
Augusto Ottoni Bueno da Silva ◽  
Newton de Oliveira Pinto Júnior ◽  
João Alberto Venegas Requena
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Three Dimensional ◽  
Analytical Calculation ◽  
Two Dimensional ◽  
Shear Forces ◽  
Vertical Displacements ◽  
New System ◽  
The Ideal

The aim of this study was to evaluate through analytical calculation, two-dimensional elastic modeling, and three-dimensional plastic modeling, the bearing capacity and failure modes of composite hollow trusses bi-supported with a 15 meter span, varying the number of central Vierendeel panels. The study found the proportion span/3 - span/3 - span/3, as the ideal relationship for the truss - Vierendeel - truss lengths, because by increasing the proportion of the length occupied by the central Vierendeel panels, the new system loses stiffness and no longer supports the load stipulated in the project. Furthermore, they can start presenting excessive vertical displacements and insufficient resistance to external shear forces acting on the panels.

Processing of Nanoporous Gold by Dealloying and its Morphological Control

2007 ◽  
Vol 561-565 ◽  
pp. 1657-1660 ◽  
Author(s):  
Masataka Hakamada ◽  
Mamoru Mabuchi
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Acid Treatment ◽  
Nanoporous Gold ◽  
Anisotropic Structure ◽  
Ideal Strength ◽  
Pore Characteristics ◽  
Very High ◽  
Ligament Size ◽  
The Ideal

Nanoporous gold was fabricated by dealloying and their pore characteristics were further modified by thermal or acid treatment. The fabricated nanoporous gold had a ligament size of approximately 5 nm. Thermal treatment on the nanoporous gold increased the ligament size to approximately 500 nm. During the thermal treatment, ligaments are bonded across the cracks which had been generated during the dealloying. Acid treatment also increased the ligament size to approximately 500 nm; however, the acid treatment had a different effect on the pore characteristics from the thermal treatment. As a result, nanoporous gold prism microassembly with anisotropic structure was spontaneously fabricated by the acid treatment. The mechanical properties of nanoporous gold were also examined. It is estimated that the yield strength of nanosized ligaments in nanoporous gold is very high and close to the ideal strength of gold.

On the Ideal Strength of Crystals

1989 ◽  
Vol 151 (1) ◽  
pp. 85-93 ◽  
Author(s):  
J. Pokluda ◽  
P. Šandera
Keyword(s):  
Ideal Strength ◽  
The Ideal

Two-dimensional generalizations of the Newcomb equation

1990 ◽  
Vol 43 (2) ◽  
pp. 291-310 ◽  
Author(s):  
R. L. Dewar ◽  
A. Pletzer
Keyword(s):  
Rational Surface ◽  
Cylindrical Symmetry ◽  
Two Dimensional ◽  
Transformation Theory ◽  
Continuous Symmetry ◽  
Scalar Form ◽  
Complicated Form ◽  
Dimensional Equation ◽  
Zero Frequency ◽  
The Ideal

The Bineau reduction to scalar form of the equation governing ideal zero-frequency linearized displacements from a hydromagnetic equilibrium possessing a continuous symmetry is performed in ‘universal co-ordinates’, applicable to both the toroidal and helical cases. The resulting generalized Newcomb equation (GNE) has in general a more complicated form than the corresponding one-dimensional equation obtained by Newcomb in the case of circular cylindrical symmetry, but in this cylindrical case we show that the equation can be transformed to that of Newcomb. In the two-dimensional case there is a transformation that leaves the form of the GNE invariant and simplifies the Frobenius expansion about a rational surface, especially in the limit of zero pressure gradient. The Frobenius expansion about a mode rational surface is developed and the connection with Hamiltonian transformation theory is shown. The derivations of the ideal interchange and ballooning criteria from the formalism are discussed.

Bridging Ideal and Non-Ideal Theory

2017 ◽  
Vol 66 (4) ◽  
pp. 887-902 ◽  
Author(s):  
Alexandru Volacu
Keyword(s):  
Political Theory ◽  
Ideal Theory ◽  
Two Dimensional ◽  
Current State ◽  
The World ◽  
Normative Models ◽  
The Ideal

Many of the recent methodological debates within political theory have focused on the ideal/non-ideal theory distinction. While ideal theorists recognise the need to develop an account of the transition between the two levels of theorising, no general proposal has been advanced thus far. In this article, I aim to bridge this conceptual gap. Towards this end, I first reconstruct the ideal/non-ideal theory distinction within a simplified two-dimensional framework, which captures the primary meanings usually attributed to it. Subsequently, I use this framework to provide an algorithm for the bidirectional transition between ideal and non-ideal theory, based on the incremental derivation of normative models. The approach outlined illuminates the various ways in which principles derived under highly idealised assumptions might be distorted by the circumstances of our current world and illustrates the various paths which we can pursue in moving from our current state of the world to an ideal one.

scholarly journals An independent derivation and verification of the voids nucleation failure mechanism: significance for materials failure

2019 ◽  
Vol 475 (2222) ◽  
pp. 20180755 ◽  
Author(s):  
Richard Christensen ◽  
Zhi Li ◽  
Huajian Gao
Keyword(s):  
Stress State ◽  
Failure Mechanism ◽  
Density Functional ◽  
Failure Modes ◽  
Shear Bands ◽  
Failure Criteria ◽  
Atomic Scale ◽  
Ideal Strength ◽  
Failure Theory ◽  
The Ideal

Independent derivations are given for the failure criteria of the purely dilatational stress state involving voids nucleation failure as well as for the purely distortional stress state involving shear bands failure. The results are consistent with those from a recently derived failure theory and they further substantiate the failure theory. The voids nucleation mechanism is compared with the ideal theoretical strength of isotropic materials as derived by density functional theory and two other atomic-scale methods. It is found that a cross-over occurs from the voids nucleation failure mechanism to the ideal strength limitation as the tensile to compressive strengths ratio, T / C , increases toward a value of unity. All the results are consistent with the failure modes transition results from the general failure theory.

Mechanical Properties of Superhard Nanocomposites with High Thermal Stability

2003 ◽  
Vol 791 ◽  
Author(s):  
Stan Veprek ◽  
Ali S. Argon
Keyword(s):  
Elastic Recovery ◽  
High Hardness ◽  
Phase Segregation ◽  
Grain Boundary Sliding ◽  
Structural Flexibility ◽  
Ideal Strength ◽  
Crystallite Sizes ◽  
Boundary Sliding ◽  
Plastic Transformation ◽  
The Ideal

Abstract Superhard nanocomposites, nc-MnN/a-XxNy (M = Ti, W, V, Zr, (Al1-xTix)N; X = Si, B) with hardness of 40–100 GPa are prepared by plasma CVD or PVD under a sufficiently high nitrogen activity and deposition temperature that allow the formation of a stable nanostructure by self-organization upon strong thermodynamically driven, spinodal phase segregation. These nanocomposites display an extraordinary combination of a high hardness, high elastic recovery, high resistance against brittle fracture and tensile strength of 5 to 40 GPa approaching the ideal strength of flaw-free materials. These properties can be understood in terms of conventional fracture physics scaled appropriately down to crystallite sizes of few nm. The interfacial monolayer of Si3N4 or BN with strong bonding to the nanocrystallites and high structural flexibility avoids grain boundary sliding. With increasing thickness of this interface the hardness decreases, possibly due to an increase of this “liquid-like” component in which plastic transformation can be triggered.

The mechanical properties of perfect crystals I. The ideal strength

1972 ◽  
Vol 330 (1582) ◽  
pp. 291-308 ◽  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Sodium Chloride ◽  
Room Temperature ◽  
Cleavage Plane ◽  
Ideal Strength ◽  
Lennard Jones ◽  
Computer Calculations ◽  
The Ideal

In this paper we present computer calculations of the ideal strength of crystals of sodium chloride and argon, for a variety of modes of homogeneous deformation. As models of the interatomic binding we employ the simple, two-body, central-force Born-Mayer and Lennard-Jones potentials respectively. The calculations for argon are appropriate to absolute zero, those for sodium chloride to room temperature. The results indicate a very marked anisotropy of the ideal tensile strength for sodium chloride, with a pronounced minimum at <100>, which is consistent with the observed cleavage on this plane. The ideal tensile strength of argon is shown to be much less dependent on orientation, which accords with the lack of any obvious cleavage plane in this material. We also make some estimates of the ideal shear strength, and find this to be a minimum for {111} <112> shear for both argon and sodium chloride.

THE STABILITY OF FCC CRYSTAL Cu UNDER UNIAXIAL LOADING IN [001] DIRECTION

2009 ◽  
Vol 23 (15) ◽  
pp. 1871-1880 ◽  
Author(s):  
X. M. LIU ◽  
Z. L. LIU ◽  
X. C. YOU ◽  
J. F. NIE ◽  
Z. ZHUANG
Keyword(s):  
Hydrostatic Stress ◽  
Element Model ◽  
Uniaxial Loading ◽  
Ideal Strength ◽  
Anisotropic Character ◽  
Tension And Compression ◽  
Loading Tests ◽  
The Stability ◽  
Critical Resolved Shear Stress ◽  
The Ideal

Uniaxial loading tests of copper with inter-atomic potential finite-element model are carried out to determine the corresponding ideal tension and compression strength using the modified Born stability criteria. The influence of biaxial stresses applied perpendicularly to the [100] loading axis, on the ideal strength is investigated, and tension-compression asymmetry in ideal strength under [100] loading is also studied. The results suggest that asymmetry for yielding strength of [100] nanowires may result from anisotropic character of crystal instability. Moreover, the results also reveal that the critical resolved shear stress in the direction of slip is not an accurate criterion for the ideal strength since it cannot capture the dependence on the loading conditions and hydrostatic stress components for the ideal strength.

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