scholarly journals Structure Dependence of Poisson’s Ratio in Cesium Silicate and Borate Glasses

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2837
Author(s):  
Martin B. Østergaard ◽  
Mikkel S. Bødker ◽  
Morten M. Smedskjaer
Keyword(s):  
Poisson’S Ratio ◽  
Network Connectivity ◽  
Silicate Glasses ◽  
Poisson's Ratio ◽  
Borate Glasses ◽  
Oxide Glasses ◽  
Topological Constraint ◽  
Binary Glass ◽  
The Difference ◽  
Positive Correlations

In glass materials, Poisson’s ratio (ν) has been proposed to be correlated with a variety of features, including atomic packing density (Cg), liquid fragility (m), and network connectivity. To further investigate these correlations in oxide glasses, here, we study cesium borate and cesium silicate glasses with varying modifier/former ratio given the difference in network former coordination and because cesium results in relatively high ν compared to the smaller alkali modifiers. Within the binary glass series, we find positive correlations between ν on one hand and m and Cg on the other hand. The network former is found to greatly influence the correlation between ν and the number of bridging oxygens (nBO), with a negative correlation for silicate glasses and positive correlation for borate glasses. An analysis based on topological constraint theory shows that this difference cannot be explained by the effect of superstructural units on the network connectivity in lithium borate glasses. Considering a wider range of oxide glasses from the literature, we find that ν generally decreases with increasing network connectivity, but with notable exceptions for heavy alkali borate glasses and calcium alumino tectosilicate glasses.

scholarly journals Deformation and cracking behavior of La2O3-doped oxide glasses with high Poisson's ratio

2018 ◽  
Vol 494 ◽  
pp. 86-93 ◽  
Author(s):  
Kacper Januchta ◽  
Ruofu Sun ◽  
Liping Huang ◽  
Michal Bockowski ◽  
Sylwester J. Rzoska ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Oxide Glasses ◽  
Cracking Behavior ◽  
Doped Oxide

scholarly journals Prediction of Pore Size Characteristics of Needle-Punched Nonwoven Geotextiles Subjected to Uniaxial Tensile Strains

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lin Tang ◽  
Qiang Tang ◽  
Aolai Zhong ◽  
Hanjie Li
Keyword(s):  
Pore Size ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Uniaxial Tensile ◽  
Modified Model ◽  
Pore Sizes ◽  
Pore Size Distributions ◽  
Out Of Plane ◽  
Tensile Strains ◽  
The Difference

A modified theoretical model has been proposed to predict the pore size characteristics of nonwoven geotextiles under certain uniaxial tensile strains, considering the difference between the out-of-plane Poisson’s ratio and the in-plane Poisson’s ratio of geotextiles. The pore size distributions (PSDs) and O95 subjected to different levels of uniaxial tensile strains in two needle-punched nonwoven geotextiles have been investigated by the dry sieving test. The variation of the fibre orientation with tensile strains and the corresponding effect on pore sizes has been evaluated by image analysis. The out-of-plane Poisson’s ratio and the in-plane Poisson’s ratio of geotextiles have been examined. A comparison has been made between the predictions of the original and the modified models. It is shown that the modified model can more accurately predict the decreasing rate of the PSDs, O95, and O98 than the original one. The corrected theoretical O95 and O98 under certain strains can provide a reference for the filtration design under engineering strains. The fibres reorientating to the loading direction result in the increase of the directional parameter with increasing tensile strains, which leads to the decrease of pore sizes. The theoretical PSDs are sensitive to the variation of directional parameter.

Analysis of Spherical Contact Models for Differential Hardness as a Function of Poisson's Ratio

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Giuseppe Pintaude
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Large Deformations ◽  
Poisson's Ratio ◽  
Spherical Contact ◽  
Indentation Process ◽  
Contact Models ◽  
The Difference

A differential hardness is needed for a spherical indenter to avoid large deformations of it during an indentation process. Tabor proposes a criterion for this, where the ball hardness should be at least 2.5 times harder than the specimen. Later, five models expand the Tabor proposal, such that the critical interference corresponding to the inception of plastic deformation depends on the Poisson's ratio. This paper discusses the difference among these models, showing that they can be divided in two groups only. In addition, their similarity depending on the specific mechanical properties of tested material was used to make the conversion between yield stress and hardness.

An Application of the Interferometer Strain Gage in Photoelasticity

1935 ◽  
Vol 2 (3) ◽  
pp. A99-A102
Author(s):  
R. W. Vose
Keyword(s):  
Strain Gage ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Massachusetts Institute ◽  
Massachusetts Institute Of Technology ◽  
Lateral Deformation ◽  
Principal Stresses ◽  
Photoelastic Analysis ◽  
The Difference ◽  
Institute Of Technology

Abstract This paper was written at the suggestion of Mr. Mieth Maeser, in response to numerous inquiries concerning the methods of photoelastic analysis in use at the Massachusetts Institute of Technology. By the use of any of the usual photoelastic methods the difference of the principal stresses and their direction at any point in a suitable loaded specimen are determined, and through a knowledge of Poisson’s ratio their sum is obtained (and a solution made possible) by a measurement of the lateral deformation of the specimen by means of an interferometer strain gage. This instrument, together with its accessories and their use, is illustrated and described in the paper. Examples of the problems solved by the use of the instrument show its accuracy and the consistency of the results obtained by the method.

Structural Groupings in Borate Glasses

1985 ◽  
Vol 61 ◽  
Author(s):  
Philip J. Bray
Keyword(s):  
Long Range ◽  
Random Network ◽  
Three Dimensional ◽  
Silicate Glasses ◽  
Borate Glasses ◽  
Oxide Glasses ◽  
Atomic Arrangement ◽  
Random Manner ◽  
Continuous Random Network

A. A. Lebedev developed a crystallite model for glasses in the 1920's which was supported by the 1930 publication of Randall, Rooksby, and Cooper But, the 1932 publication by Zachariasen entitled “The Atomic Arrangement in Glass” introduced the Warren and Zachariasen continuous random network (CRN) model. In that model, as applied to oxide glasses, oxygen polyhedra surrounding cations (e.g. SiO4 tetrahedra in silicate glasses) are linked together in a random manner to form extensive three-dimensional networks which do not exhibit long-range symmetry or periodicity. Zachariasen did assume that the forces between atoms in glasses and crystals are essentially the same, and noted the same polyhedra in both, but did not discuss any further possible correspondence between glasses and crystals.

scholarly journals Improving the strength and toughness of macroscale double networks by exploiting Poisson’s ratio mismatch

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tsuyoshi Okumura ◽  
Riku Takahashi ◽  
Katsumi Hagita ◽  
Daniel R. King ◽  
Jian Ping Gong
Keyword(s):  
Poisson’S Ratio ◽  
Mechanical Performance ◽  
High Strength ◽  
Soft Materials ◽  
Strengthening Mechanism ◽  
Poisson's Ratio ◽  
Uniaxial Tensile ◽  
The Matrix ◽  
The Difference ◽  
Strength And Toughness

AbstractWe propose a new concept that utilizes the difference in Poisson's ratio between component materials as a strengthening mechanism that increases the effectiveness of the sacrificial bond toughening mechanism in macroscale double-network (Macro-DN) materials. These Macro-DN composites consist of a macroscopic skeleton imbedded within a soft elastic matrix. We varied the Poisson's ratio of the reinforcing skeleton by introducing auxetic or honeycomb functional structures that results in Poisson’s ratio mismatch between the skeleton and matrix. During uniaxial tensile experiments, high strength and toughness were achieved due to two events: (1) multiple internal bond fractures of the skeleton (like sacrificial bonds in classic DN gels) and (2) significant, biaxial deformation of the matrix imposed by the functional skeleton. The Macro-DN composite with auxetic skeleton exhibits up to 4.2 times higher stiffness and 4.4 times higher yield force than the sum of the component materials. The significant improvement in mechanical performance is correlated to the large mismatch in Poisson's ratio between component materials, and the enhancement is especially noticeable in the low-stretch regime. The strengthening mechanism reported here based on Poisson's ratio mismatch can be widely used for soft materials regardless of chemical composition and will improve the mechanical properties of elastomer and hydrogel systems.

scholarly journals Revisiting the Dependence of Poisson’s Ratio on Liquid Fragility and Atomic Packing Density in Oxide Glasses

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2439 ◽  
Author(s):  
Martin B. Østergaard ◽  
Søren R. Hansen ◽  
Kacper Januchta ◽  
Theany To ◽  
Sylwester J. Rzoska ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Packing Density ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Oxide Glass ◽  
High Fracture Toughness ◽  
Zinc Borate ◽  
Oxide Glasses ◽  
Atomic Packing ◽  
Liquid Fragility

Poisson’s ratio (ν) defines a material’s propensity to laterally expand upon compression, or laterally shrink upon tension for non-auxetic materials. This fundamental metric has traditionally, in some fields, been assumed to be a material-independent constant, but it is clear that it varies with composition across glasses, ceramics, metals, and polymers. The intrinsically elastic metric has also been suggested to control a range of properties, even beyond the linear-elastic regime. Notably, metallic glasses show a striking brittle-to-ductile (BTD) transition for ν-values above ~0.32. The BTD transition has also been suggested to be valid for oxide glasses, but, unfortunately, direct prediction of Poisson’s ratio from chemical composition remains challenging. With the long-term goal to discover such high-ν oxide glasses, we here revisit whether previously proposed relationships between Poisson’s ratio and liquid fragility (m) and atomic packing density (Cg) hold for oxide glasses, since this would enable m and Cg to be used as surrogates for ν. To do so, we have performed an extensive literature review and synthesized new oxide glasses within the zinc borate and aluminoborate families that are found to exhibit high Poisson’s ratio values up to ~0.34. We are not able to unequivocally confirm the universality of the Novikov-Sokolov correlation between ν and m and that between ν and Cg for oxide glass-formers, nor for the organic, ionic, chalcogenide, halogenide, or metallic glasses. Despite significant scatter, we do, however, observe an overall increase in ν with increasing m and Cg, but it is clear that additional structural details besides m or Cg are needed to predict and understand the composition dependence of Poisson’s ratio. Finally, we also infer from literature data that, in addition to high ν, high Young’s modulus is also needed to obtain glasses with high fracture toughness.

scholarly journals Calculation of lateral stresses for uniaxial compression of geomaterial samples

2021 ◽  
Vol 929 (1) ◽  
pp. 012015
Author(s):  
A A Kirilov ◽  
V N Sychev
Keyword(s):  
Mechanical Stress ◽  
Uniaxial Compression ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Transverse Stress ◽  
Measured Load ◽  
The Difference ◽  
Transverse Stresses ◽  
Analytical Expressions

Abstract A method is proposed for calculating the transverce stresses during uniaxial compression of geomaterial samples from the measured load and mutually perpendicular deformations. Analytical expressions connecting the indicated parameters are obtained. The dependences of the change in the calculated transverse stresses on time are plotted for various values of Poisson’s ratio. The difference in transverse stresses demonstrates a much greater sensitivity to mechanical stress than each transverse stress separately. Sharp changes in the values of the difference in transverse stresses are observed, which coincide with bursts of AE activity.

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