scholarly journals Microstructure and Macromechanical Properties of Retaining Structure of Near-Water Reinforced Soil under Dry-Wet Cycle

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Yujie Hou ◽  
Bo Wang ◽  
Liang Huang ◽  
Jianguo Xu ◽  
Dun Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Surface ◽  
Reinforced Soil ◽  
Overburden Pressure ◽  
Soil Particles ◽  
Retaining Structure ◽  
Pull Out ◽  
Long Time ◽  
Reinforced Materials

Reinforced soil-retaining structures that have been working in near-water environments for a long time are likely to affect their own mechanical properties due to the dry-wet cycle caused by changes in water level. In response to this problem, this paper uses a combination of macro- and microtests, selecting reinforced soil samples with four water content conditions, five overburden pressure conditions, three sets of dry-wet cycle conditions, and a total of 60 working conditions for testing. Scanning electron microscopy was used to observe the microscopic characterization of the reinforced soil particles under different times of the dry-wet cycle, and the pull-out test was used to study the mechanical properties of the interface of the reinforced materials and soils. The analysis results of the test show that the dry-wet cycles increase the porosity of the reinforced soil and the number of pores, among which the proportion of micro and small pores increases, the abundance and fractal dimension of reinforced soil particles increase, and the roughness of the particle surface is reduced. The change of the microstructure of the reinforced soil causes the cohesion of the soil to decrease in the macroscopic view. The friction coefficient and the ultimate pull-out force of the interface between the reinforced materials and the soils decrease with the increase of times of dry-wet cycle.

scholarly journals Experimental Study on Mechanical Properties of Reinforced Soil Interface under Dry-Wet Cycle

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Liang Huang ◽  
Wenbo Ma ◽  
Yujie Hou ◽  
Bo Wang ◽  
Jiahua Zhu
Keyword(s):  
Mechanical Properties ◽  
Water Content ◽  
Working Conditions ◽  
Retaining Wall ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Overburden Pressure ◽  
Pull Out ◽  
Apparent Cohesion ◽  
Soil Interface

The reinforced soil-retaining wall has been widely used in coastal projects, and the dry-wet cycles influence the mechanical properties of the reinforced soil interface. This study conducts macro-micro tests and selects four different water content samples of reinforced soil with five types of overburden pressure conditions and three sets of dry-wet cycles, with a total of 60 working conditions. The pull-out test was used to study the mechanical properties of the reinforced soil interface. The scanning electron microscope was used to observe the microscopic characterization of the particles under different working conditions. Through the analysis of the experimental results, we can draw the conclusion as follows. (1) The friction coefficient of the reinforced soil interface decreases with the increase of the number of dry and wet cycles. (2) The apparent cohesion of soil-reinforcement interface decreases with the increase of the number of dry-wet cycles. After 30 dry-wet cycles, the apparent cohesion of the soil-reinforcement interface with water content of 14% is the maximum 5.91 kPa. The variation law of cohesion derived from microstructure analysis conforms to the laws and conclusions obtained by the experiment. (3) The shear stress of the reinforced soil is linearly related to the normal stress, which is in accordance with Coulomb’s law.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

PREPARATION AND CHARACTERIZATION OF PLASTICIZED POLYLACTIC ACID/STARCH BLEND

2016 ◽  
Vol 78 (11-2) ◽  
Author(s):  
Fathilah Ali ◽  
Raina J.Awale ◽  
Mohamed Elwathig Saeed Mirghani ◽  
Hazleen Anuar ◽  
Norasikin Samat
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Polylactic Acid ◽  
Mechanical And Thermal Properties ◽  
Melt Blending ◽  
Infra Red ◽  
Long Time ◽  
Ft Ir ◽  
The Cost

Petroleum based packaging materials has raised environmental concerns due to its non-environmentally friendly degradation. Conventional plastic takes a long time to degrade and remains in the waste dump. Since then, attention to biodegradable plastics has been heightened for its greener degradation. Polylactic acid (PLA) is a renewable polymer with mechanical properties comparable to those of the conventional plastics. This study aims to improve the mechanical and thermal properties and reducing the cost of PLA production by blending PLA with starch as filler and epoxy palm oil (EPO) as plasticizer. The PLA/starch/EPO blends were prepared by solution casting and melt blending methods and properties of the blends were studied and characterized. The thermal properties of plasticized PLA/starch were investigated by Differential Screening Calorimetry (DSC) followed by Fourier Transform Infra-Red Spectroscopy (FT-IR) in order to observe the degree of interaction of plasticized PLA/starch blend. The mechanical properties were investigated using Universal Tensile Test

scholarly journals Characterization of Atrial Septal Defect Occluders by right and left atrial pull-out forces

2019 ◽  
Vol 5 (1) ◽  
pp. 457-459
Author(s):  
Markus Brudsche ◽  
Bruno Ismer ◽  
Nikolaus A. Haas
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Left Atrial ◽  
Septal Defect ◽  
Septal Defects ◽  
Pull Out ◽  
Special Measuring ◽  
Measuring Setup

AbstractOccluders made of the shape memory alloy Nitinol are commonly used to close Atrial Septal Defects (ASD). Until now, standard parameters are missing defining the mechanical properties of these implants. In this study, we developed a special measuring setup for the determination of the mechanical properties of customly available occluders (i.e. Occlutech Figulla® Flex II 29ASD12 and AGA AMPLATZER™ 9-ASD-012).

scholarly journals Measuring mechanical anisotropy on geogrid reinforced soil using a cubical triaxial apparatus

2019 ◽  
Vol 92 ◽  
pp. 12008
Author(s):  
Pedro A. Covassi ◽  
Víctor A. Rinaldi
Keyword(s):  
Reinforced Soil ◽  
Mechanical Anisotropy ◽  
Experimental Program ◽  
Octahedral Plane ◽  
Stress Strain ◽  
Triaxial Apparatus ◽  
Pull Out ◽  
Triaxial Cell ◽  
Lode Angle

This work describes the main findings of an experimental program focused on the characterization of the mechanical anisotropy of a reinforced cohesive soil using a cubical triaxial apparatus. Several authors have studied the influence of geometry, type, number and arrangement of reinforcement layers on the mechanical behaviour of reinforced soils, mainly dedicated to evaluate the improvement of stiffness and strength. The influence of anisotropy and principal intermediate stress has not been addressed. Conventional triaxial cell (axisymmetric) and pull-out tests are the most common type of devices used in the present studies. The implementation of an experimental program using a cubical triaxial apparatus allows us to consider all the aspects mentioned before, mainly those related to an anisotropic characterization and the principal intermediate stress influence on stress-strain and strength behaviour. Results obtained in this work, show that reinforced soil is a cross-anisotropic material, and its stress-strain and strength behaviour is strongly influenced in sectors I (lode angle between 0° and 60°) and II (lode angle between 60° and 120°) of the octahedral plane. Thus, a complete characterization of geogrid reinforced soil can be made selecting an appropriate set of stress paths in the cubical apparatus.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Advances in ultramicrotomy for physical sciences applications

1993 ◽  
Vol 51 ◽  
pp. 710-711
Author(s):  
G. McMahon ◽  
T. Malis
Keyword(s):  
Particle Surface ◽  
Zeolite Catalysts ◽  
Physical Sciences ◽  
Pull Out ◽  
Large Particles ◽  
Novel Applications ◽  
Metal Wires ◽  
Frequent Problem ◽  
Specific Orientation ◽  
Diamond Knife

As with all techniques which are relatively new and therefore underutilized, diamond knife sectioning in the physical sciences continues to see both developments of the technique and novel applications.Technique Developments Development of specific orientation/embedding procedures for small pieces of awkward shape is exemplified by the work of Bradley et al on large, rather fragile particles of nuclear waste glass. At the same time, the frequent problem of pullout with large particles can be reduced by roughening of the particle surface, and a proven methodology using a commercial coupling agent developed for glasses has been utilized with good results on large zeolite catalysts. The same principle (using acid etches) should work for ceramic fibres or metal wires which may only partially pull out but result in unacceptably thick sections. Researchers from the life sciences continue to develop aspects of embedding media which may be applicable to certain cases in the physical sciences.

A Thorough Theoretical Exploration of Intriguing Characteristics of Cyclo[18]carbon: Geometry, Bonding Nature, Aromaticity, Weak Interaction, Reactivity, Excited States, Vibrations, Molecular Dynamics and Various Molecular Properties

2019 ◽  
Author(s):  
Tian Lu ◽  
Qinxue Chen ◽  
Zeyu Liu
Keyword(s):  
Molecular Dynamics ◽  
Excited States ◽  
Electronic Excitation ◽  
Ring Structure ◽  
Molecular Properties ◽  
Molecular Vibration ◽  
Full Characterization ◽  
Long Time ◽  
Almost All

Although cyclo[18]carbon has been theoretically and experimentally investigated since long time ago, only very recently it was prepared and directly observed by means of STM/AFM in condensed phase (Kaiser et al., <i>Science</i>, <b>365</b>, 1299 (2019)). The unique ring structure and dual 18-center π delocalization feature bring a variety of unusual characteristics and properties to the cyclo[18]carbon, which are quite worth to be explored. In this work, we present an extremely comprehensive and detailed investigation on almost all aspects of the cyclo[18]carbon, including (1) Geometric characteristics (2) Bonding nature (3) Electron delocalization and aromaticity (4) Intermolecular interaction (5) Reactivity (6) Electronic excitation and UV/Vis spectrum (7) Molecular vibration and IR/Raman spectrum (8) Molecular dynamics (9) Response to external field (10) Electron ionization, affinity and accompanied process (11) Various molecular properties. We believe that our full characterization of the cyclo[18]carbon will greatly deepen researchers' understanding of this system, and thereby help them to utilize it in practice and design its various valuable derivatives.

A Thorough Theoretical Exploration of Intriguing Characteristics of Cyclo[18]carbon: Geometry, Bonding Nature, Aromaticity, Weak Interaction, Reactivity, Excited States, Vibrations, Molecular Dynamics and Various Molecular Properties

2019 ◽  
Author(s):  
Tian Lu ◽  
Qinxue Chen ◽  
Zeyu Liu
Keyword(s):  
Molecular Dynamics ◽  
Excited States ◽  
Electronic Excitation ◽  
Ring Structure ◽  
Molecular Properties ◽  
Molecular Vibration ◽  
Full Characterization ◽  
Long Time ◽  
Almost All

Although cyclo[18]carbon has been theoretically and experimentally investigated since long time ago, only very recently it was prepared and directly observed by means of STM/AFM in condensed phase (Kaiser et al., <i>Science</i>, <b>365</b>, 1299 (2019)). The unique ring structure and dual 18-center π delocalization feature bring a variety of unusual characteristics and properties to the cyclo[18]carbon, which are quite worth to be explored. In this work, we present an extremely comprehensive and detailed investigation on almost all aspects of the cyclo[18]carbon, including (1) Geometric characteristics (2) Bonding nature (3) Electron delocalization and aromaticity (4) Intermolecular interaction (5) Reactivity (6) Electronic excitation and UV/Vis spectrum (7) Molecular vibration and IR/Raman spectrum (8) Molecular dynamics (9) Response to external field (10) Electron ionization, affinity and accompanied process (11) Various molecular properties. We believe that our full characterization of the cyclo[18]carbon will greatly deepen researchers' understanding of this system, and thereby help them to utilize it in practice and design its various valuable derivatives.

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