Synthesis and characterization of the physical, chemical and mechanical properties of isocyanate-crosslinked vanadia aerogels

Luo, Huiyang; Churu, Gitogo; Fabrizio, Eve F.; Schnobrich, Jennifer K.; Hobbs, Abigail; Dass, Amala; Mulik, Sudhir; Zhang, Y.; Grady, Brian P.; Capecelatro, Alex; Sotiriou‐Leventis, Chariklia; Lu, Hongbing; Leventis, Nicholas

doi:10.1007/s10971-008-1788-y

Cited by 60 publications

(51 citation statements)

References 36 publications

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“…They also calculated the evolution of Poisson's ratio from the ratio of the average measured longitudinal and transverse strains (ν = −ε yy /ε xx ). In the same way, Luo et al studied the compressive behaviour of vanadia aerogels using a SHPB and the same camera with an interframe time of 14 μs (frequency: 72,000 fps) [10]. Once again, the strains appeared to be mainly homogeneous at these high-strain rates.…”

Section: Full-field Kinematic Measurements At High Strain Rates Usingmentioning

confidence: 97%

“…In the three last quoted papers, ultra-high speed imaging systems have been used to measure full-field of rather large strains (several tens of percent) [9,10] or to extract a single displacement value from the fullfield measurement (thus not really taking advantage of the available spatial information) [11]. A very recent paper also mentions the use of a Cordin 550-32 UHS camera to measure strain maps of small magnitude [12].…”

Section: Full-field Kinematic Measurements At High Strain Rates Usingmentioning

confidence: 99%

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Full-Field Strain Measurement and Identification of Composites Moduli at High Strain Rate with the Virtual Fields Method

et al. 2010

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Abstract The present paper deals with full-field strain measurement on glass/epoxy composite tensile specimens submitted to high strain rate loading through a split Hopkinson pressure bar (SHPB) device and with the identification of their mechanical properties. First, the adopted methodology is presented: the device, including an Ultra-High Speed camera, and the experimental procedure to obtain relevant displacement maps are described. The different full-field results including displacement, strain and acceleration maps for two mechanical tests are then addressed. The last part of the paper deals with an original procedure to identify stiffnesses on this dynamic case only using the actual strain and acceleration maps (without the applied force) by using the Virtual Fields Method.

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Section: Full-field Kinematic Measurements At High Strain Rates Usingmentioning

confidence: 97%

Section: Full-field Kinematic Measurements At High Strain Rates Usingmentioning

confidence: 99%

Full-Field Strain Measurement and Identification of Composites Moduli at High Strain Rate with the Virtual Fields Method

et al. 2010

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“…In this case, the most basic use of the full-field data consists in using it as a noncontact strain gauge by averaging the strains over the field of view (e.g. [12][13][14][15][16]) while checking that the strain field was reasonably uniform. Such measurements have also been used to have better insights into strain localization in uniaxial tests [17,18].…”

Section: Introductionmentioning

confidence: 99%

Beyond Hopkinson's bar

Pierron

Zhu

Siviour

2014

Phil. Trans. R. Soc. A.

122

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In order to perform experimental identification of high strain rate material models, engineers have only a very limited toolbox based on test procedures developed decades ago. The best example is the so-called split Hopkinson pressure bar based on the bar concept introduced 100 years ago by Bertram Hopkinson to measure blast pulses. The recent advent of full-field deformation measurements using imaging techniques has allowed novel approaches to be developed and exciting new testing procedures to be imagined for the first time. One can use this full-field information in conjunction with efficient numerical inverse identification tools such as the virtual fields method (VFM) to identify material parameters at high rates. The underpinning novelty is to exploit the inertial effects developed in high strain rate loading. This paper presents results from a new inertial impact test to obtain stress–strain curves at high strain rates (here, up to 3000 s −1 ). A quasi-isotropic composite specimen is equipped with a grid and images are recorded with the new HPV-X camera from Shimadzu at 5 Mfps and the SIMX16 camera from Specialised Imaging at 1 Mfps. Deformation, strain and acceleration fields are then input into the VFM to identify the stiffness parameters with unprecedented quality.

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“…This was done to maintain the heterogeneous distribution of sand grains. The length of the assembly was measured from time to time to check if the sand specimen 36 was compacted to the desired packing density.…”

Section: Methodsmentioning

confidence: 99%

Mechanics of Granular Materials: Experimentation and Simulations for Determining the Compressive and Shear Behaviors of Sand at Granular and Meso Scales

Komanduri¹,

Lu²,

Subramanian³

et al. 2011

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We present the results of experiments conducted to study the compressive and shear behavior of sand. Static and dynamic studies on the compression of sand grains were conducted. Nanoindentation was performed on single grains on sand of different sizes in order to determine the elastic and fracture properties of individual sand grains. Finite Element method (FEM) was used to solve the inverse problem so as to obtain the material properties from the load-displacement curves obtained from nanoindentation experiments. We also report the results of quasi-static compression tests conducted on sand held in a passive confinement. An in-house built compression fixture enabled the compression of sand grains up to axial stresses as high as 3 GPa. The results of tests conducted to study the dynamic behavior of ensemble to sand grains to compressive loading are also presented. Dynamic compression tests at strain rates of ∼700 s −1 were performed using a split Hopkinson pressure bar (SHPB). Characterization of sand grains based on initial packaging density, moisture content and different confinement materials were performed. In-situ quasi-static compression of sand grains along with X-ray micro-computed tomography was performed. Images from the tomographs were combined with the axial stress-strain data to explain various phenomenon such as re-arrangement and eventual fracture of grains during compression. Results obtained from various experiments performed in the course of this study would serve to validate the analytical models on mechanical behavior of sand. IntroductionGranular or particulate materials are ensembles of discrete macroscopic particles that respond to external forces only via inter-particle contact forces. They resemble solids as they behave rigidly under compression due to grain interlocking. Due to discrete and unbonded nature of the grains, they cannot withstand any load under tension. When the interlocking between the grains collapse, they lose resistance to shear loading and exhibit flow behavior similar to that of a viscous fluid. The solid-liquid transitional behavior of 2 the granular materials can be observed in grains stored in silos to landslides. They resemble liquids by assuming the shape of the container that they are stored and resemble gases as they lack intergranular cohesion. Jaeger et al. describe granular materials as "unusual" solids, liquids or gases [31]. They describe granular materials as a unique state of matter. The study of granular materials is currently active in various fields of engineering and sciences; including physics, geophysics, mechanics, and pharmaceuticals. Sand is a granular material found abundantly in nature. It has a hard structure with particle size varying between 7.5 µm and 4.75 mm. It primarily consists of silica (SiO 2 ) while other constituents, such as magnetite, gypsum, chlorite are present in minor quantities and vary from one geographic location to the other. Sand is usually described by their composition, morphology (shape), size, color, and text...

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Synthesis and characterization of the physical, chemical and mechanical properties of isocyanate-crosslinked vanadia aerogels

Cited by 60 publications

References 36 publications

Full-Field Strain Measurement and Identification of Composites Moduli at High Strain Rate with the Virtual Fields Method

Full-Field Strain Measurement and Identification of Composites Moduli at High Strain Rate with the Virtual Fields Method

Beyond Hopkinson's bar

Mechanics of Granular Materials: Experimentation and Simulations for Determining the Compressive and Shear Behaviors of Sand at Granular and Meso Scales

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