Numerical Simulation and Microscopic Stress Mechanism for the Microscopic Pore Deformation during Soil Compression

Pore structure is closely related with strength, constitutive relation, consolidation characteristics, and permeability properties of soil. Consequently, improving the understanding of the relationship between microscopic structure and macroscopic physical and mechanical properties has extremely important scientific significance. A large number of studies have shown that pores of soil have fractal features, and hence, the carpet model can be used to approximately simulate the fractal structure of clay. In the present study, ANSYS software was selected to establish a microscopic model of clay to study the distribution of microscopic stress and microscopic deformation characteristics of pores under different consolidation pressures. Besides, the variation law of microscopic pore size was quantitatively determined by using IPP (Image-Pro Plus) software. Combined with the fractal theory, the changes of microscopic pore of numerical simulation and that of physical experiment during compression of clay are studied. All the results indicated that the microscopic stress distribution of clay is not uniform on the compaction process. The larger the pore size is, the bigger the compression stress on both sides and the greater the bending deformation of upper part of the pore is, which leads to the deformation of larger pores which is bigger than that of smaller pores. Based on the results, issues about the microscopic mechanism of the difference in vertical and horizontal permeability under compression of clay, the relationship between the changes of pore shape and microscopic stress, the preliminary principle of “preferential crush of larger particles” for granular soil, skeleton stress across the region where stiffness is relative larger, and the self-protection of particles and pores are also discussed. The results of this study are of great importance in understanding of soil compression and related physical and mechanical properties from the microscopic view.

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Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork

CivilEng ◽

10.3390/civileng2020029 ◽

2021 ◽

Vol 2 (2) ◽

pp. 523-540

Author(s):

Imed Beghoura ◽

Joao Castro-Gomes

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Pore Size ◽

Physical And Mechanical Properties ◽

Critical Parameters ◽

Porous Structures ◽

Foaming Agent ◽

Al Powder ◽

Highly Porous ◽

Alkali Activated

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.

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Recycled Mortars with Ceramic Aggregates. Pore Network Transmutation and Its Relationship with Physical and Mechanical Properties

Materials ◽

10.3390/ma14061543 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1543

Author(s):

Francisca Guadalupe Cabrera-Covarrubias ◽

José Manuel Gómez-Soberón ◽

Carlos Antonio Rosas-Casarez ◽

Jorge Luis Almaral-Sánchez ◽

Jesús Manuel Bernal-Camacho

Keyword(s):

Mechanical Properties ◽

Image Analysis ◽

Open Porosity ◽

Gas Adsorption ◽

Physical And Mechanical Properties ◽

Recycled Aggregate ◽

Bet Surface Area ◽

Sem Image ◽

The Relationship ◽

Sem Image Analysis

The porosity of mortars with recycled ceramic aggregates (10, 20, 30, 50, and 100% as a replacement of natural aggregate) was evaluated and analyzed using three different techniques. The results of gas adsorption (N2), Scanning Electron Microscopy (SEM) image analysis and open porosity allowed establishing the relationship between the recycled aggregate content and the porosity of these mortars, as well as the relationship between porosity and the physical and mechanical properties of the mortars: absorption, density, compressive strength, modulus of elasticity, and drying shrinkage. Using the R2 coefficient and the equation typology as criteria, additional data such as Brunauer, Emmett, and Teller (BET) surface area (N2 adsorption) established significant correlations with the mentioned properties; with SEM image analysis, no explanatory relationships could be established; and with open porosity, revealing relationships were established (R2 > 0.9). With the three techniques, it was confirmed that the increase in porosity is related to the increase in the amount of ceramic aggregate; in particular with gas adsorption (N2) and open porosity. It was concluded that the open porosity technique can explain the behavior of these recycled mortars with more reliable data, in a simple and direct way, linked to its establishment with a more representative sample of the mortar matrix.

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Influence of different concentrations of fibrinogen on the properties of a fibrin matrix for vascular tissue engineering

I P Pavlov Russian Medical Biological Herald ◽

10.23888/pavlovj202129121-34 ◽

2021 ◽

Vol 29 (1) ◽

pp. 21-34

Author(s):

Vera G. Matveeva ◽

Mariam Yu. Khanova ◽

Tatyana V. Glushkova ◽

Larisa V. Antonova

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

Metabolic Activity ◽

Vascular Tissue ◽

Physical And Mechanical Properties ◽

Vascular Tissue Engineering ◽

Test Machine ◽

Fibrin Matrix ◽

Before And After ◽

The Difference

Aim. To evaluate the potential utility of fibrin matrices containing 10, 20, and 25 mg/ml of fibrinogen (fibrin-10, fibrin-20, and fibrin-30, respectively) in vascular tissue engineering (VTE). Materials and Methods. Fibrinogen was isolated using the method of ethanol cryoprecipitation and polymerized using a solution of thrombin and CaCl2. The fibrin structure was studied in a scanning electron microscope, and the physical and mechanical properties of the material were tested on a Zwick/Roell test machine. The metabolic activity of endothelial cells (EC) on the fibrin surface was evaluated by the MTT assay, and the viability of fibroblasts in the thickness of fibrin and possibility for migration by in fluorescent and light microscopy. Percent of fibrin shrinkage was determined from the difference in the sample volumes before and after removal of moisture. Results. The fiber diameter did not differ among all fibrin samples, but the pore diameter in fibrin-30 was smaller than those in fibrin-10 and fibrin-20. A possibility for migration of fibroblasts into the depth of the fibrin matrix and preservation of 97-100% viability of cells at a depth 5 mm was confirmed. The metabolic activity of EC on the surface of fibrin-20 and fibrin-30 exceeded that on collagen, fibronectin, and fibrin-10. All fibrin samples shrank in volume to 95.5-99.5%, and the highest shrinkage was seen in fibrin-10. The physical and mechanical properties of fibrin were inferior to those of human A. mammaria by a factor of 10. Conclusion. Fibrin with fibrinogen concentrations of 20 and 30 mg/ml maintains a high metabolic and proliferative activity of EC on the surface and also a high viability of fibroblasts in the matrix. Its availability, ease of preparation, and a number of other favorable properties make fibrin a promising material for VTE. However, the problem of insufficient strength requires further investigations.

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AN INVESTIGATION ON THE EFFECTS OF MICRO-PARAMETERS ON THE STRENGTH PROPERTIES OF ROCK

Rudarsko-geološko-naftni zbornik ◽

10.17794/rgn.2021.1.9 ◽

2021 ◽

Vol 36 (1) ◽

pp. 111-119

Author(s):

Behzad Jafari Mohammadabadi ◽

Kourosh Shahriar ◽

Hossein Jalalifar ◽

Kaveh Ahangari

Keyword(s):

Mechanical Properties ◽

Numerical Simulation ◽

Tensile Strength ◽

Compressive Strength ◽

Friction Coefficient ◽

Critical Stress ◽

Friction Angle ◽

Strength Properties ◽

Brazilian Tensile Strength ◽

The Relationship

Rocks are formed from particles and the interaction between those particles controls the behaviour of a rock’s mechanical properties. Since it is very important to conduct extensive studies about the relationship between the micro-parameters and macro-parameters of rock, this paper investigates the effects of some micro-parameters on strength properties and the behaviour of cracks in rock. This is carried out by using numerical simulation of an extensive series of Uniaxial Compressive Strength (UCS) and Brazilian Tensile Strength (BTS) tests. The micro-parameters included the particles’ contact modulus, the contact stiff ness ratio, bond cohesion, bond tensile strength, the friction coefficient and the friction angle, and the mechanical properties of chromite rock have been considered as base values of the investigation. Based on the obtained results, it was found that the most important micro-parameters on the behaviour of rock in the compressive state are bond cohesion, bond tensile strength, and the friction coefficient. Also, the bond tensile strength showed the largest effect under tensile conditions. The micro-parameter of bond tensile strength increased the rock tensile strength (up to 5 times), minimized destructive cracks and increased the corresponding strain (almost 2.5 times) during critical stress.

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Differences in petrophysical and mechanical properties between low- and middle-rank coal subjected to liquid nitrogen cooling in coalbed methane mining

Journal of Energy Resources Technology ◽

10.1115/1.4052614 ◽

2021 ◽

pp. 1-10

Author(s):

Menglin Du ◽

Feng Gao ◽

Chengzheng Cai ◽

Shanjie Su ◽

Zekai Wang

Keyword(s):

Mechanical Properties ◽

Pore Structure ◽

Liquid Nitrogen ◽

Coalbed Methane ◽

Bituminous Coal ◽

Thermal Damage ◽

Physical And Mechanical Properties ◽

Damage Degree ◽

Lignite Coal ◽

The Difference

Abstract Exploring the damage differences between different coal rank coal reservoirs subjected to liquid nitrogen (LN2) cooling is of great significance to the rational development and efficient utilization of coalbed methane. For this purpose, the mechanical properties, acoustic emission (AE) characteristics and energy evolution law of lignite and bituminous coal subjected to LN2 cooling were investigated based on the Brazilian splitting tests. Then, pore structure changes were analyzed to reveal the difference in the microscopic damage between lignite and bituminous coal after LN2 cooling. The results showed that compared with bituminous coal, the pore structure of lignite coal changed more obviously, which was manifested as follows: significant increases in porosity, pore diameters, and pore area; a larger transformation from micropores and transition pores to mesopores and macropores. After LN2 cooling, the thermal damage inside lignite and bituminous coal was 0.412 and 0.069, respectively. The thermal damage reduced the cohesive force between mineral particles, leading to the deterioration of the macroscopic physical and mechanical properties. Simultaneously, denser AE ringing counts and larger accumulated ringing counts were observed after LN2 cooling. Moreover, the random distribution of thermal damage enhanced the randomness of the macrocrack propagation direction, resulting in an increase in the crack path tortuosity. With more initial defects inside coal, a more obvious thermal damage degree and wider damage distribution will be induced by LN2 cooling, leading to more complicated crack formation paths and a higher fragmentation degree, such as that of lignite coal.

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Thermodynamics of stressed systems

Thermodynamics and Kinetics in Materials Science ◽

10.1093/oso/9780198528036.003.0009 ◽

2005 ◽

Author(s):

Boris S. Bokstein ◽

Mikhail I. Mendelev ◽

David J. Srolovitz

Keyword(s):

Mechanical Properties ◽

Thermodynamic Functions ◽

School Child ◽

Displacement Vector ◽

Mechanical Deformation ◽

Material Point ◽

General Description ◽

The Difference ◽

Point To Point ◽

The Relationship

As every school child knows, the difference between a solid and a liquid is that a liquid takes the shape of the container in which it is placed while the shape of a solid is independent of the shape of the container (providing the container is big enough). In other words, we must apply a force in order to change the shape of a solid. However, the thermodynamic functions described heretofore have no terms that depend on shape. In this chapter, we extend the thermodynamics discussed above to include such effects and therefore make it applicable to solids. However, since this is a thermodynamics, rather than a mechanics text, we focus more on the relationship between stress and thermodynamics rather than on a general description of the mechanical properties of solids. We start out discussion of mechanical deformation by describing the change of shape of a solid. We define the displacement vector at any point in the solid u(x, y, z) as the change in location of the material point (x, y, z) upon deformation: that is, ux(x, y, z) = x' - x, where the prime indicates the coordinates of the material that was at the unprimed position prior to the deformation. In linear elasticity, we explicitly assume that the displacement vector varies slowly from point to point within the solid where i and j denote the directions along the three axes, x, y, and z. Consider the small parallel-piped section of a solid with perpendicular edges shown in Fig. 7.1. We label the first corner as O, located at position (xO, yO, zO) and subsequent corners as A, B, . . . located at positions (xA, yA, zA), (xB, yB, zB), . . . The edge lengths are Δx, Δy, and Δz such that, for example, xA = xO + Δx. As a result of the deformation, the material originally at point O is displaced to point O' with coordinates (x'O, y'O, z'O).

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Thermal and Mechanical Properties of Cyclized Polybutadiene Dielectrics

MRS Proceedings ◽

10.1557/proc-76-359 ◽

1986 ◽

Vol 76 ◽

Author(s):

C. W. Wilkins ◽

H. E. Bair ◽

M. G. Chan ◽

R. S. Hutton

Keyword(s):

Mechanical Properties ◽

Differential Scanning Calorimetry ◽

Physical And Mechanical Properties ◽

Mechanical Analysis ◽

Infrared Analysis ◽

Thermal And Mechanical Properties ◽

Scanning Calorimetry ◽

The Difference ◽

Thermal Mechanical Analysis ◽

Lower Glass Transition Temperature

ABSTRACTWe have studied some of the physical and mechanical properties of cyclized polybutadiene (CBR) dielectrics by dynamic mechanical analysis, thermal mechanical analysis, thermogravimetry, infrared analysis, and differential scanning calorimetry. Of interest is the difference in properties between thin (<30 μm) films which have been cured under vacuum and those which have been cured in air. Our results indicate that curing under vacuum prevents oxidation and reduces crosslinking. Vacuum cured films have 20% smaller moduli and 200 lower glass transition temperature than do films produced in air.

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Fabrication of Porous Polyethylene by Two-Stepped Heat Treatment and Powder Printing Technique

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.93-94.165 ◽

2010 ◽

Vol 93-94 ◽

pp. 165-168 ◽

Cited By ~ 3

Author(s):

Jintamai Suwanprateeb ◽

Kitiya Wasoontararat ◽

Waraporn Suvannapruk

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

High Density Polyethylene ◽

Physical And Mechanical Properties ◽

High Density ◽

Processing Conditions ◽

Structure And Properties ◽

Porous Polyethylene ◽

Printing Technique ◽

The Relationship

In this study, a combination of powder printing technique and two-stepped heat treatment was utilized as a mean to prepare porous high density polyethylene structure. Physical and mechanical properties of the resulting structure were then characterized by porosity measurement and monotonic tensile test. It was found that the relationship between structure and properties was strongly influenced by processing conditions including compositions, treatment times and treatment temperatures. This process could increase the properties of porous high density polyethylene significantly over the single-stepped heat treatment without destroying porous structure. Porous high density polyethylene bodies having a porosity ranging from 46-58 percents with tensile strength up to approximately 4 MPa could be successfully prepared in this study.

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Synthesis and Properties of Electroconductive Polymeric Composite Material Based on Polypyrrole

ISRN Polymer Science ◽

10.5402/2012/320316 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 6

Author(s):

N. S. Ilicheva ◽

N. K. Kitaeva ◽

V. R. Duflot ◽

V. I. Kabanova

Keyword(s):

Mechanical Properties ◽

Composite Material ◽

Mechanical Strength ◽

Process Parameters ◽

Physical And Mechanical Properties ◽

Polymeric Composite ◽

Polymeric Composite Material ◽

Elastic Composite ◽

The Relationship

A technique is proposed for obtaining electroconductive, mechanically strong, and elastic composite material based on polypyrrole and hydrophilized polyethylene. The relationship is established between the process parameters and properties of the composite material such as electroconductivity and mechanical strength. Several methods are considered in the view of increasing electroconductivity of the material. Physical and mechanical properties of the composite material are investigated.

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Interpreting research results for the physical and mechanical properties of wood: An approach not dependent on a juvenile/mature wood boundary

BioResources ◽

10.15376/biores.16.4.6921-6932 ◽

2021 ◽

Vol 16 (4) ◽

pp. 6921-6932

Author(s):

Tomislav Sinković ◽

Branimir Jambreković ◽

Tomislav Sedlar

Keyword(s):

Mechanical Properties ◽

Radial Direction ◽

Statistical Tests ◽

Physical And Mechanical Properties ◽

Wood Properties ◽

Mature Wood ◽

Raw Material ◽

Technological Properties ◽

Wood Processing ◽

The Difference

The interpretation and presentation of research on the physical and mechanical properties of wood in the radial direction is important for the estimation of technological properties in primary wood processing. It is common practice to define the boundary between the juvenile and mature wood zone of tree growth because of the differences in wood properties in these two zones. The juvenile and mature wood zones can be determined statistically based on the significance of the difference in the properties in a particular zone. This paper presents the insufficiency in the statistical determination of the boundary between juvenile and adult wood. Such limitations detract from the potential value and technological exploitation of wood as raw material. Statistical tests yielded zones that were too wide for the transition of juvenile wood to mature wood. Representations of the distribution of properties in the radial direction also complement the knowledge for assessing the technological properties based on the researched use of the presentation of polynomials of the second degree and the display of the Tukey HSD test in the form of comparison tables. The graphical representations by groups of the tested annual rings of fir wood also help to assess the technological properties.

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