scholarly journals Temperature-Dependent Stiffening and Inelastic Behavior of Newly Synthesized Fiber-Reinforced Super Flexible Silica Aerogels

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2878
Author(s):  
Ameya Rege ◽  
Pascal Voepel ◽  
Emrah Okumus ◽  
Markus Hillgärtner ◽  
Mikhail Itskov ◽  
...  
Keyword(s):  
Silica Aerogels ◽  
Fiber Types ◽  
Static Tension ◽  
Inelastic Behavior ◽  
Temperature Dependent ◽  
Acoustic Insulation ◽  
Tension And Compression ◽  
Synthesis Procedure ◽  
Strength And Durability ◽  
Significant Attention

In recent years, flexible silica aerogels have gained significant attention, owing to their excellent thermal and acoustic insulation properties accompanied by mechanical flexibility. Fiber reinforcement of such aerogels results in a further enhancement of the strength and durability of the composite, while retaining the excellent insulation properties. In this paper, the influence of four different kinds of fibers within a flexible silica aerogel matrix is studied and reported. First, a description of the synthesis procedure and the resulting morphology of the four aerogel composites is presented. Their mechanical behavior under uniaxial quasi-static tension and compression is investigated, particularly their performance under uniaxial compression at different temperature conditions (50 °C, 0 °C, and −50 °C). The reinforcement of the flexible silica aerogels with four different fiber types only marginally influences the thermal conductivity but strongly enhances their mechanical properties.

scholarly journals A General Temperature-Dependent Stress–Strain Constitutive Model for Polymer-Bonded Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1393
Author(s):  
Xiaochang Duan ◽  
Hongwei Yuan ◽  
Wei Tang ◽  
Jingjing He ◽  
Xuefei Guan
Keyword(s):  
Composite Materials ◽  
Constitutive Model ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Stress Strain ◽  
Proposed Model ◽  
Single Temperature ◽  
Testing Data ◽  
Bonded Composite ◽  
Tension And Compression

This study develops a general temperature-dependent stress–strain constitutive model for polymer-bonded composite materials, allowing for the prediction of deformation behaviors under tension and compression in the testing temperature range. Laboratory testing of the material specimens in uniaxial tension and compression at multiple temperatures ranging from −40 ∘C to 75 ∘C is performed. The testing data reveal that the stress–strain response can be divided into two general regimes, namely, a short elastic part followed by the plastic part; therefore, the Ramberg–Osgood relationship is proposed to build the stress–strain constitutive model at a single temperature. By correlating the model parameters with the corresponding temperature using a response surface, a general temperature-dependent stress–strain constitutive model is established. The effectiveness and accuracy of the proposed model are validated using several independent sets of testing data and third-party data. The performance of the proposed model is compared with an existing reference model. The validation and comparison results show that the proposed model has a lower number of parameters and yields smaller relative errors. The proposed constitutive model is further implemented as a user material routine in a finite element package. A simple structural example using the developed user material is presented and its accuracy is verified.

scholarly journals Temperature-dependent yield asymmetry between tension and compression in metallic glasses

2012 ◽  
Vol 61 (3) ◽  
pp. 036201
Author(s):  
Chen Yan ◽  
Jiang Min-Qiang ◽  
Dai Lan-Hong
Keyword(s):  
Metallic Glasses ◽  
Temperature Dependent ◽  
Tension And Compression

A Review of Aerogels and Their Application as a Multi-functional Building Material

2012 ◽  
Vol 253-255 ◽  
pp. 564-567 ◽  
Author(s):  
Zhu Ge Yan
Keyword(s):  
Mechanical Behaviour ◽  
Building Material ◽  
Energy Efficient ◽  
Silica Aerogels ◽  
Material Characterisation ◽  
Energy Efficient Buildings ◽  
Acoustic Insulation ◽  
New Material ◽  
New Type ◽  
Energy Efficient Building

This paper will provide a review of the current research on the material characterisation and mechanical behaviour of polymer enhanced silica aerogels. Aerogels have been in existence for many years; however, the engineering applications of aerogels have been limited due to their poor mechanical behaviour. Recently a new type of polymer enhanced silica aerogel, a nanostructured form of silica has been developed. The new material is having a low density, very low thermal conductivity, excellent acoustic insulation and high mechanical which makes it ideal for energy efficient building material. This paper will discuss the start-of-the-art development of this material and issues to apply the material in energy efficient buildings.

scholarly journals Insights into the Lithium Substructure of the Superionic Conductors Li3YCl6 and Li3YBr6

2020 ◽  
Author(s):  
Roman Schlem ◽  
Ananya Banik ◽  
Saneyuki Ohni ◽  
Emmanuelle Suard ◽  
Wolfgang Zeier
Keyword(s):  
Solid State ◽  
Solid Electrolytes ◽  
Superionic Conductors ◽  
Synthetic Approach ◽  
Temperature Dependent ◽  
Recent Interest ◽  
Solid State Battery ◽  
Synthesis Procedure ◽  
Battery Application ◽  
Shed Light

The recent interest in the halide-based solid electrolytes Li<sub>3</sub>MX<sub>6</sub> (M = Y, Er, In; X = Cl, Br, I) shows these materials to be promising candidates for solid-state battery application, due to high ionic conductivity and large electrochemical stability window. However, almost nothing is known about the underlying lithium sub-structure within those compounds. Here, we investigate the lithium sub-structure of Li<sub>3</sub>YCl<sub>6</sub> and Li<sub>3</sub>YBr<sub>6</sub> using temperature-dependent neutron diffraction. We compare compounds prepared by classic solid-state syntheses with a mechanochemical synthesis to shed light on the influence of the synthetic approach on the reported yttrium disorder and the resulting surrounding lithium sub-structure. This work provides a better understanding of the strong differences in ionic transport depending on the synthesis procedure of Li<sub>3</sub>MX<sub>6</sub>.

scholarly journals Fractal Structure in Silica and Composites Aerogels

Gels ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Thierry Woignier ◽  
Juan Primera ◽  
Adil Alaoui ◽  
Philippe Dieudonne ◽  
Laurent Duffours ◽  
...  
Keyword(s):  
Fractal Structure ◽  
High Surface ◽  
High Surface Area ◽  
Silica Aerogels ◽  
High Porosity ◽  
Material Density ◽  
X Ray ◽  
Synthesis Conditions ◽  
Fractal Characteristics ◽  
Synthesis Procedure

Silica aerogels are known to be materials with exceptional characteristics, such as ultra-low density, high surface area, high porosity, high adsorption, and low-thermal conductivity. In addition, these unique properties are mainly related to their specific processing. Depending on the aerogel synthesis procedure, the aerogels texture can be tailored with meso and/or macroporosity. Fractal geometry has been observed and used to describe silica aerogels at nanoscales in certain conditions. In this review paper, we describe the fractal structure of silica aerogels that can develop depending on the synthesis conditions. X-ray and neutron scattering measurements allow to show that silica aerogels can exhibit a fractal structure over one or even more than two orders of magnitude in length. The fractal dimension does not depend directly on the material density but can vary with the synthesis conditions. It ranges typically between 1.6 and 2.4. The effect of the introduction of silica particles or of further thermal treatment or compression of the silica aerogels on their microstructure and their fractal characteristics is also resumed.

Temperature dependent microstructure of MTES modified hydrophobic silica aerogels

2011 ◽  
Vol 65 (4) ◽  
pp. 606-609 ◽  
Author(s):  
Sheng Cui ◽  
Yu Liu ◽  
Mao-hong Fan ◽  
Adrienne T. Cooper ◽  
Ben-lan Lin ◽  
...  
Keyword(s):  
Silica Aerogels ◽  
Temperature Dependent ◽  
Hydrophobic Silica

Synthesis and Thermoelectric Properties of Lead Chalcogenide Nanocomposites

2007 ◽  
Vol 1044 ◽  
Author(s):  
Joshua Martin ◽  
Stevce Stefanoski ◽  
Li Wang ◽  
Lidong Chen ◽  
George S. Nolas
Keyword(s):  
Lead Telluride ◽  
Phase Reaction ◽  
Conductivity Measurements ◽  
Lead Chalcogenide ◽  
Temperature Dependent ◽  
Plasma Sintering ◽  
Nanocrystal Synthesis ◽  
Spark Plasma ◽  
Synthesis Procedure ◽  
Temperature Dependent Resistivity

AbstractDoped lead telluride dimensional nanocomposites were prepared by densifying nanocrystals synthesized employing an alkaline aqueous solution-phase reaction. The nanocrystal synthesis procedure resulted in high product yields of over 2 g per batch. These nanocrystals were then subjected to Spark Plasma Sintering (SPS) for densification. Transport properties were evaluated through temperature dependent resistivity, Hall, Seebeck coefficient, and thermal conductivity measurements. The results for these lead telluride nanocomposites were compared to bulk polycrystalline lead tellurides with similar carrier concentrations.

scholarly journals Insights into the Lithium Substructure of the Superionic Conductors Li3YCl6 and Li3YBr6

2020 ◽  
Author(s):  
Roman Schlem ◽  
Ananya Banik ◽  
Saneyuki Ohni ◽  
Emmanuelle Suard ◽  
Wolfgang Zeier
Keyword(s):  
Solid State ◽  
Solid Electrolytes ◽  
Superionic Conductors ◽  
Synthetic Approach ◽  
Temperature Dependent ◽  
Recent Interest ◽  
Solid State Battery ◽  
Synthesis Procedure ◽  
Battery Application ◽  
Shed Light

The recent interest in the halide-based solid electrolytes Li<sub>3</sub>MX<sub>6</sub> (M = Y, Er, In; X = Cl, Br, I) shows these materials to be promising candidates for solid-state battery application, due to high ionic conductivity and large electrochemical stability window. However, almost nothing is known about the underlying lithium sub-structure within those compounds. Here, we investigate the lithium sub-structure of Li<sub>3</sub>YCl<sub>6</sub> and Li<sub>3</sub>YBr<sub>6</sub> using temperature-dependent neutron diffraction. We compare compounds prepared by classic solid-state syntheses with a mechanochemical synthesis to shed light on the influence of the synthetic approach on the reported yttrium disorder and the resulting surrounding lithium sub-structure. This work provides a better understanding of the strong differences in ionic transport depending on the synthesis procedure of Li<sub>3</sub>MX<sub>6</sub>.

scholarly journals A Temperature-Dependent Model of Shape Memory Alloys Considering Tensile-Compressive Asymmetry and the Ratcheting Effect

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3116
Author(s):  
Longfei Wang ◽  
Peihua Feng ◽  
Ying Wu ◽  
Zishun Liu
Keyword(s):  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Internal Variables ◽  
Cyclic Tests ◽  
Temperature Dependent ◽  
Proposed Model ◽  
Tension And Compression ◽  
Dependent Model ◽  
Temperature Dependent Model

Tensile-compressive asymmetry and the ratcheting effect are two significant characteristics of shape memory alloys (SMAs) during uniaxial cyclic tests, thus having received substantial attention in research. In this study, by redefining the internal variables in SMAs by considering the cyclic accumulation of residual martensite, we propose a constitutive model for SMAs to simultaneously reflect tensile-compressive asymmetry and the cyclic ratcheting effect under multiple cyclic tests. This constitutive model is temperature dependent and can be used to reasonably capture the typical features of SMAs during tensile-compressive cyclic tests, which include the pseudo-elasticity at higher temperatures as well as the shape-memory effect at lower temperatures. Moreover, the proposed model can predict the cyclic mechanical behavior of SMAs subjected to applied stresses with different peak and valley values under tension and compression. Agreement between the predictions obtained from the proposed model and the published experimental data is observed, which confirms that the proposed novel constitutive model of SMAs is feasible.

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