scholarly journals Analysis of elastic behaviour of granite using homogenisation theory

2006 ◽  
Vol 34 ◽  
pp. 25-28
Author(s):  
Y. Baek ◽  
O. I. Kweon ◽  
Y. S. Seo ◽  
K. S. Kim ◽  
G. W. K im
Keyword(s):  
Composite Material ◽  
Numerical Analysis ◽  
Mechanical Tests ◽  
Representative Elementary Volume ◽  
Elastic Behaviour ◽  
Specimen Preparation ◽  
Elementary Volume ◽  
Discrete Elements ◽  
Fine Grained ◽  
Photographic Analysis

We carried out photographic analysis of randomly distributed discrete elements in the lnada granite. The modal analysis of granite was also conducted simultaneously with the above photographic analysis. The results show that quartz and feldspar including mica occupy 99.4% of the total volume of the fine-grained granite. Based on the results of previous studies, an elastic homogenisation method is applied to analyse the macro-level stress distribution in the lnada granite, which is a composite material of rock-forming minerals with micro discontinuities. For proper rock sampling and specimen preparation, the representative elementary volume (REV) should be determined in rock mechanical tests and numerical analyses. We determined the REV of the lnada granite using a stereoscopic microscope and applying a homogenisation numerical analysis.

scholarly journals New insights on homogenization for hexagonal-shaped composites as Cosserat continua

Meccanica ◽  
2021 ◽  
Author(s):  
Marco Colatosti ◽  
Nicholas Fantuzzi ◽  
Patrizia Trovalusci ◽  
Renato Masiani
Keyword(s):  
Continuum Theory ◽  
Representative Elementary Volume ◽  
Elementary Volume ◽  
Displacement Fields ◽  
Micropolar Continuum ◽  
Rigid Particles ◽  
Hexagonal Shape ◽  
Classical Models ◽  
Elastic Interfaces ◽  
Cosserat Continua

AbstractIn this work, particle composite materials with different kind of microstructures are analyzed. Such materials are described as made of rigid particles and elastic interfaces. Rigid particles of arbitrary hexagonal shape are considered and their geometry is described by a limited set of parameters. Three different textures are analyzed and static analyses are performed for a comparison among the solutions of discrete, micropolar (Cosserat) and classical models. In particular, the displacements of the discrete model are compared to the displacement fields of equivalent micropolar and classical continua realized through a homogenization technique, starting from the representative elementary volume detected with a numeric approach. The performed analyses show the effectiveness of adopting the micropolar continuum theory for describing such materials.

Recovery of Waste Leather From Tanneries as Aggregate in Composite Materials

2020 ◽  
Vol 65 (2) ◽  
pp. 39-55
Author(s):  
Gabriela-Emilia Popița ◽  
◽  
Cristina Roșu ◽  
Dorin Manciula ◽  
Ofelia Corbu ◽  
...  
Keyword(s):  
Composite Material ◽  
Construction Material ◽  
Mechanical Tests ◽  
Economic Benefits ◽  
Cement Matrix ◽  
Production Flow ◽  
Total Chromium ◽  
Glass Waste ◽  
Recovery Method ◽  
Leather Waste

This study proposes a recovery method for waste leather from tanneries, with high chromium content, by incorporating it into a composite material with cement matrix. The natural aggregates were substituted with CRT (cathode ray tubes) glass waste, with high lead content, originated from televisions and monitors dismantling. The material technological production flow was as follows: grinding skin (two types of skin: black and brown were used), mixing the ingredients after own recipes, pouring the mixture into molds, maturation, demoulding. The new material obtained was submitted to leachability tests to determine, using AAS (Atomic Absorption Spectrometry), the total chromium and lead concentration released from the material. The results showed that Cr and Pb were well retained in the cement matrix. The low levels of total Cr and Pb concentration were recorded at pH = 9-10 and pH = 12, for the composite containing black leather waste and and at pH = 2-3 and pH = 12 for the composite containing brown leather waste. Mechanical tests were also provided to evidence the mechanical properties of the composite. The new composite material obtained may be considered as construction material and can be classified in mortars class because of the size of the used aggregate (CRT glass waste). The objective of this study was to obtain a composite material that can be used as material for construction, in compliance with current standards in construction and environmental legislation. The proposed method for leather waste recovery is viable and environmentally friendly and could bring economic benefits. Keywords: leather, waste, CRT, composite, material.

scholarly journals Estimating the Effect of Fractal Dimension on Representative Elementary Volume of Randomly Distributed Rock Fracture Networks

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Jing Zhang ◽  
Liyuan Yu ◽  
Hongwen Jing ◽  
Richeng Liu
Keyword(s):  
Fractal Dimension ◽  
Functional Relationship ◽  
Rock Fracture ◽  
Representative Elementary Volume ◽  
Width Ratio ◽  
Elementary Volume ◽  
Equivalent Permeability ◽  
Length Width ◽  
Rock Fracture Networks

The effect of fractal dimension (Df) on the determination of representative elementary volume (REV) was investigated through numerical experimentations, in which a new method was adopted to extract submodels that have different length-width ratios from original discrete facture networks (DFNs). Fluid flow in 1610 DFNs with different geometric characteristics of fractures and length-width ratios was simulated, and the equivalent permeability was calculated. The results show that the average equivalent permeability (KREV) at the REV size for DFNs increases with the increase in Df. The KREV shows a downward trend with increasing length-width ratio of the submodel. A strong exponent functional relationship is found between the REV size and Df. The REV size decreases with increasing Df. With the increment of the length-width ratio of submodels, the REV size shows a decreasing trend. The effects of length-width ratio and Df on the REV size can be negligible when Df≥1.5, but are significant when Df<1.5.

scholarly journals Tension mechanical properties of recycled glass-epoxy composite material

2012 ◽  
pp. 189-198 ◽  
Author(s):  
Jelena Petrovic ◽  
Darko Ljubic ◽  
Marina Stamenovic ◽  
Ivana Dimic ◽  
Slavisa Putic
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Material ◽  
Composite Materials ◽  
Modulus Of Elasticity ◽  
Epoxy Composite ◽  
Raw Materials ◽  
Mechanical Tests ◽  
Recycled Glass ◽  
Before And After

The significance of composite materials and their applications are mainly due to their good properties. This imposes the need for their recycling, thus extending their lifetime. Once used composite material will be disposed as a waste at the end of it service life. After recycling, this kind of waste can be used as raw materials for the production of same material, which raises their applicability. This indicates a great importance of recycling as a method of the renowal of composite materials. This study represents a contribution to the field of mechanical properties of the recycled composite materials. The tension mechanical properties (tensile strength and modulus of elasticity) of once used and disposed glass-epoxy composite material were compared before and after the recycling. The obtained results from mechanical tests confirmed that the applied recycling method was suitable for glass-epoxy composite materials. In respect to the tensile strength and modulus of elasticity it can be further assessed the possibility of use of recycled glass-epoxy composite materials.

scholarly journals Determination of representative elementary volume (REV) for jointed rock masses exhibiting scale-dependent behavior: A numerical investigation

2021 ◽  
Author(s):  
Mehmet Sari
Keyword(s):  
Jointed Rock ◽  
Representative Elementary Volume ◽  
Elementary Volume ◽  
Rock Masses ◽  
Continuum Approach ◽  
Joint Spacing ◽  
Jointed Rock Masses ◽  
Equivalent Continuum ◽  
Equivalent Continuum Approach

Abstract Representative elementary volume (REV) is defined as the usual size of a rock mass structure beyond which its mechanical properties are homogenous and isotropic, and its behavior can be modeled using the equivalent continuum approach. Determination of REV is a complex problem in rock engineering due to its definition ambiguity and application area. This study is one of the first attempts to define a REV for jointed rock masses using the equivalent continuum approach. It is aimed to numerically search a ratio between the characteristic size of an engineering structure and pre-existing joint spacing, which are the two most important contributing elements in assessing REV. For this purpose, four hypothetical engineering cases were investigated using the RS2 (Phase2 v. 9.0) finite element (FE) analysis program. An underground circular opening with a constant diameter, an open-pit mine with varying bench heights, a single bench with a constant height, and an underground powerhouse cavern with a known dimension were executed for possible changes in the safety factor and total displacement measurements under several joint spacing values. Different cut-off REVs were calculated for FE models depending on the type of excavation and measurement method. An average REV size of 19.0, ranging between a minimum of 2 for tunnels and a maximum of 48 for slopes, was found in numerical analysis. The calculated sizes of REV were significantly larger than the range of values (5 to 10) commonly reported in the relevant geotechnical literature.

scholarly journals Upscaling of elastic properties in carbonates: A modeling approach based on a multiscale geophysical data set

2020 ◽  
Author(s):  
Jerome Fortin ◽  
Cedric Bailly ◽  
Mathilde Adelinet ◽  
Youri Hamon
Keyword(s):  
Elastic Properties ◽  
Wave Velocity ◽  
Representative Elementary Volume ◽  
P Wave ◽  
Elementary Volume ◽  
Data Set ◽  
Wave Velocities ◽  
P Wave Velocity ◽  
Ultrasonic Measurements ◽  
Seismic Scale

&lt;p&gt;Linking ultrasonic measurements made on samples, with sonic logs and seismic subsurface data, is a key challenge for the understanding of carbonate reservoirs. To deal with this problem, we investigate the elastic properties of dry lacustrine carbonates. At one study site, we perform a seismic refraction survey (100 Hz), as well as sonic (54 kHz) and ultrasonic (250 kHz) measurements directly on outcrop and ultrasonic measurements on samples (500 kHz). By comparing the median of each data set, we show that the P wave velocity decreases from laboratory to seismic scale. Nevertheless, the median of the sonic measurements acquired on outcrop surfaces seems to fit with the seismic data, meaning that sonic acquisition may be representative of seismic scale. To explain the variations due to upscaling, we relate the concept of representative elementary volume with the wavelength of each scale of study. Indeed, with upscaling, the wavelength varies from millimetric to pluri-metric. This change of scale allows us to conclude that the behavior of P wave velocity is due to different geological features (matrix porosity, cracks, and fractures) related to the different wavelengths used. Based on effective medium theory, we quantify the pore aspect ratio at sample scale and the crack/fracture density at outcrop and seismic scales using a multiscale representative elementary volume concept. Results show that the matrix porosity that controls the ultrasonic P wave velocities is progressively lost with upscaling, implying that crack and fracture porosity impacts sonic and seismic P wave velocities, a result of paramount importance for seismic interpretation based on deterministic approaches.&lt;/p&gt;&lt;p&gt;Bailly, C., Fortin, J., Adelinet, M., &amp; Hamon, Y. (2019). Upscaling of elastic properties in carbonates: A modeling approach based on a multiscale geophysical data set. Journal of Geophysical Research: Solid Earth, 124. https://doi.org/10.1029/2019JB018391&lt;/p&gt;

scholarly journals Preparation of a Composite Material from Palm Oil Fiber and an Ecological Emulsion of Expanded Polystyrene Post-Consumption

2020 ◽  
Vol 29 (54) ◽  
pp. e10489
Author(s):  
Cindy Gutiérrez-Estupiñán ◽  
José Gutiérrez-Gallego ◽  
Melba Sánchez-Soledad
Keyword(s):  
Composite Material ◽  
Citrus Sinensis ◽  
Natural Fibers ◽  
Mechanical Tests ◽  
Expanded Polystyrene ◽  
Environmental Crisis ◽  
Microscopy Technique ◽  
Fiber Size ◽  
Wide Availability ◽  
Useful Life

The overproduction of plastics and the wide availability of natural fibers that become a source of contamination before ending their useful life, in a context of environmental crisis, has led researchers to study how to integrate them into the production of biocomposites. For this project, the development of a composite material that integrated expanded post-consumer polystyrene (EPS) and palm fiber (OPEFB) was proposed. OPEFB fibers were obtained from palm growers in the region, being processed by drying, grinding and sieving with a particle size (Mesh of 30,40, 50, 60 and 70). To obtain the solvent of the EPS, a volume of orange essential oil (Citrus sinensis) was distilled off by steam and the amount of d-limonene present was quantified using the gas chromatography technique coupled to mass spectrometry. Subsequently, the EPS was dissolved and a solubility of 0.5 g / mL was reached and with this volume a 1: 2 water / EPS-Citrus Sinensis emulsion was formulated which was characterized using the optical microscopy technique and two dyes of different polarity to observe its affinity with both phases, allowing it to be classified as a W/O type macroemulsion. The agglomerates were made by a process of molding, pressing and heating for baking. All the above parameters were kept constant and only the fiber size varied. The tests of resistance to compression and hardness showed that, to a smaller fiber size, less hardness, resistance to compression and stiffness, so the specimens made with mesh fibers (Mesh) No. 40 showed better performance in mechanical tests.

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