scholarly journals Experimental Analysis of Mechanical Anisotropy of Selected Roofing Felts

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6907
Author(s):  
Bartosz Łuczak ◽  
Wojciech Sumelka ◽  
Artur Wypych
Keyword(s):  
Entire Range ◽  
Tensile Load ◽  
Mechanical Anisotropy ◽  
Material Anisotropy ◽  
Microstructure Characteristics ◽  
Specific Direction ◽  
Comprehensive Knowledge ◽  
Strength Tests ◽  
Unique Study ◽  
Scanning Electron

In this work, four representatives of roofing felts are under consideration. Special attention is paid to the mechanical behaviour under the tensile load of the samples. The results of strength tests for the entire range of material work, from the first load to sample breaking, are shown with respect to a specific direction of sample cutting. Moreover, a unique study of the microstructure obtained with the scanning electron microscope and chemical composition determined by energy dispersive spectroscopy of the tested materials is presented. The significant mechanical material anisotropy is reported and moreover argued by microstructure characteristics. In perspective, the outcomes can give comprehensive knowledge on optimal usage of roofing felt and proper mathematical modelling.

EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE CHARACTERISTICS OF LASER COMPOSITES

2014 ◽  
Vol 21 (01) ◽  
pp. 1450014
Author(s):  
PENG LIU ◽  
YUANBIN ZHANG ◽  
YAJIANG LI ◽  
QINGQING YANG ◽  
YAN LIU ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electron Microscope ◽  
Theoretical Basis ◽  
Laser Alloying ◽  
Wear Properties ◽  
Microstructure Characteristics ◽  
Transmission Electron ◽  
Treatment Technologies ◽  
Intensity Transfer ◽  
Scanning Electron

In this paper, effect of heat treatment on the microstructures and wear properties of laser alloying (LA) composites is investigated. LA of the T - Co 50/ FeSi / TiC / TiN / CeO 2 mixed powders on substrate of 45 steel can form the hard composites, which increased the wear resistance of substrate greatly. Such LA composites were investigated by means of a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The tempering promoted the growth of the block-shape hard phases, favoring an enhancement of the integrity of block-shape hard phases; and tempering also improved greatly the formation mechanism, guarantying the composites to have enough ability of intensity transfer. This research provided essential experiment and theoretical basis to promote the application of the laser and heat treatment technologies in the field of surface modification.

scholarly journals Study on Strength Characteristics of Solidified Contaminated Soil under Freeze-Thaw Cycle Conditions

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Qiang Wang ◽  
Jinyang Cui
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Contaminated Soils ◽  
Unconfined Compressive Strength ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Strength Tests ◽  
Freeze Thaw Cycle ◽  
Microcosmic Mechanism ◽  
Scanning Electron

Cement solidification/stabilization is a commonly used method for the remediation of contaminated soils. The stability characteristics of solidified/stabilized contaminated soils under freeze-thaw cycle are very important. A series of tests, which include unconfined compressive strength tests, freeze-thaw cycle tests, and scanning electron microscopy (SEM) tests, are performed to study the variation law of strength characteristics and microstructure. It aims at revealing the microcosmic mechanism of solidified/stabilized Pb2+ contaminated soils with cement under freeze-thaw cycle. The results show that the unconfined compressive strength of the contaminated soils significantly improved with the increase of the cement content. The unconfined compressive strength of stabilized contaminated soils first increases with the increase of times of freeze-thaw cycle, and after reaching the peak, it decreases with the increase of times of freeze-thaw cycle. The results of the scanning electron microscopy tests are consistent with those of the unconfined compressive strength tests. This paper also reveals the microcosmic mechanism of the changes in engineering of the stabilized contaminated soils under freeze-thaw cycle.

Microstructure of Omani expansive soils

1999 ◽  
Vol 36 (2) ◽  
pp. 272-290 ◽  
Author(s):  
Amer Ali Al-Rawas ◽  
A McGown
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Clay Minerals ◽  
Expansive Soils ◽  
Microstructure Characteristics ◽  
Three Samples ◽  
Two Samples ◽  
Scanning Electron

The fundamental factors controlling the expansive nature of Omani soils are their characteristics with respect to geology, mineralogy, engineering, and microstructure. The first three factors have been extensively studied, however, the fourth has not yet been fully investigated and no work has been published on this aspect. Therefore, this paper deals with the microstructure characteristics of these soils. The scanning electron microscope was employed in this investigation. Three samples selected from different sites where expansive soils problems were known (Al-Khod, Al-Murtafa'a, and Duqm) were investigated. Two specimens from each sample, representing the vertical and horizontal planes, were tested. In addition, two samples that were subjected to swelling were tested to investigate the microfabric changes caused by swelling. The fabric of the Omani expansive soils studied generally consists of dense clay matrices, although clay-granular matrices are occasionally observed. In addition, no connectors have been observed and only few aggregations have been seen. Pore spaces are mainly of the intra-assemblage and intra-elemental types. Significant microfabric changes were induced by swelling.Key words: microstructure, microfabric, SEM, expansive soils, Oman, clay minerals.

Generalized Anisotropic Inverse Mechanics for Soft Tissues

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Ramesh Raghupathy ◽  
Victor H. Barocas
Keyword(s):  
Inverse Problem ◽  
Finite Element ◽  
Soft Tissues ◽  
Mechanical Anisotropy ◽  
Cauchy Stress ◽  
Two Dimensional ◽  
Material Anisotropy ◽  
Inhomogeneous Materials ◽  
Multiple Tests ◽  
Inhomogeneous Systems

Elastography, which is the imaging of soft tissues on the basis of elastic modulus (or, more generally, stiffness) has become increasingly popular in the last decades and holds promise for application in many medical areas. Most of the attention has focused on inhomogeneous materials that are locally isotropic, the intent being to detect a (stiff) tumor within a (compliant) tissue. Many tissues of mechanical interest, however, are anisotropic, so a method capable of determining material anisotropy would be attractive. We present here an approach to determine the mechanical anisotropy of inhomogeneous, anisotropic tissues, by directly solving the finite element representation of the Cauchy stress balance in the tissue. The method divides the sample domain into subdomains assumed to have uniform properties and solves for the material constants in each subdomain. Two-dimensional simulated experiments on linear anisotropic inhomogeneous systems demonstrate the ability of the method, and simulated experiments on a nonlinear model demonstrate the ability of the method to capture anisotropy qualitatively even though only a linear model is used in the inverse problem. As with any inverse problem, ill-posedness is a serious concern, and multiple tests may need to be done on the same sample to determine the properties with confidence.

Load–Velocity Relationship in National Paralympic Powerlifters: A Case Study

2019 ◽  
Vol 14 (4) ◽  
pp. 531-535 ◽  
Author(s):  
Irineu Loturco ◽  
Lucas A. Pereira ◽  
Ciro Winckler ◽  
Weverton L. Santos ◽  
Ronaldo Kobal ◽  
...  
Keyword(s):  
Entire Range ◽  
Bench Press ◽  
Linear Regression Analysis ◽  
Dynamic Strength ◽  
Movement Velocity ◽  
Predictive Equations ◽  
Velocity Relationship ◽  
Strength Tests ◽  
Mean Differences

Purpose: To examine the relationships between different loading intensities and movement velocities in the bench-press exercise (BP) in Paralympic powerlifters. Methods: A total of 17 national Paralympic powerlifters performed maximum dynamic strength tests to determine their BP 1-repetition maximum (1RM) in a Smith-machine device. A linear position transducer was used to measure movement velocity over a comprehensive range of loads. Linear-regression analysis was performed to establish the relationships between the different bar velocities and the distinct percentages of 1RM. Results: Overall, the correlations between bar velocities and %1RM were strong over the entire range of loads (R2 .80–.91), but the precision of the predictive equations (expressed as mean differences [%] between actual and predicted 1RM values) were higher at heavier loading intensities (∼20% for loads ≤70% 1RM and ∼5% for loads ≥70% 1RM). In addition, it seems that these very strong athletes (eg, 1RM relative in the BP = 2.22 [0.36] kg·kg−1, for male participants) perform BP 1RM assessments at lower velocities than those previously reported in the literature. Conclusions: The load–velocity relationship was strong and consistent in Paralympic powerlifters, especially at higher loads (≥70% 1RM). Therefore, Paralympic coaches can use the predictive equations and the reference values provided here to determine and monitor the BP loading intensity in national Paralympic powerlifters.

scholarly journals A Calculation Theory of Earth Pressure Considering Microstructure of Porous Materials

2018 ◽  
Vol 142 ◽  
pp. 02010
Author(s):  
Jun-hu Li ◽  
Chao Zhang ◽  
Wei Xue ◽  
Wen-chao Zhang ◽  
Ri-qing Xu
Keyword(s):  
Contact Area ◽  
Soft Clay ◽  
Stress Transfer ◽  
Earth Pressure ◽  
Transfer Principle ◽  
Lateral Stress ◽  
Microstructure Characteristics ◽  
Pressure Calculation ◽  
The Relationship ◽  
Scanning Electron

To explore a more reasonable earth pressure calculation theory, microstructure characteristics of soft clay in Hangzhou, Ningbo and Wenzhou had been observed using scanning electron microscope (SEM) and were quantitatively analysed using Image-Pro Plus (IPP) software. The relationship between porosity and contact area of soft clay was got by considering the microstructure. Combining soil lateral stress transfer principle, a calculation theory of earth pressure considering soil contact area was got. The possible reason of the differences between earth pressure and the actual monitoring earth pressure was analysis by the case.

scholarly journals Comparative Analysis on the Micropore and Microstructure Characteristics of Concrete under Insulated Formwork

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2862
Author(s):  
Myung-Kwan Lim ◽  
Kyung-Yong Nam
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Term Strength ◽  
Microstructure Characteristics ◽  
Hot Air ◽  
Chemical Admixture ◽  
Form Effect ◽  
Scanning Electron

During concrete construction in winter, the concrete performance is generally improved by adding a chemical admixture or providing protection using tents and hot-air blowers. However, long-term strength or safety accidents may occur due to the installation and removal of the tents. This study considered insulated gang forms to improve formwork methods. In this regard, the microstructure and micropore characteristics of concrete were investigated experimentally to examine the insulated gang form effect on the physical and mechanical properties of concrete. The micropore characteristics were investigated through scanning electron microscopy. The results confirm that applying insulated gangs improves workability and safety without adding chemical admixture. Moreover, the application of insulated gang forms reduces the use of tents and hot-air blowers. Therefore, insulated gangs provide excellent initial quality to the concrete.

scholarly journals Novel Masonry Grout Incorporating High Volumes of Industrial By-Products: Microstructure Characteristics and Pursuance of Durability Properties

2021 ◽  
Author(s):  
R. Ramesh Nayaka ◽  
U. Johnson Alengaram ◽  
Mohd Zamin Jumaat ◽  
Rathish Kumar P ◽  
Fernando S Fonseca ◽  
...  
Keyword(s):  
Palm Oil ◽  
Affordable Housing ◽  
Building Materials ◽  
Drying Shrinkage ◽  
Microstructure Characteristics ◽  
Masonry Construction ◽  
Strength Tests ◽  
Rate Of Absorption ◽  
Sustainable Materials ◽  
By Products

Abstract One solution to the high cost and scarcity of building materials is to use alternative and sustainable materials. The study presented herein developed an eco-friendly masonry grout using high volumes of palm oil clinker powder to replace cement and palm oil clinker to replace coarse aggregate. Several batches of grouts with different amounts of these materials were made to determine the technical viability of the grout. SEM and XRD analyses were conducted to investigate the microstructure characteristics of the grout, and water absorption, initial rate of absorption, sulphate attack and electrical resistivity tests were conducted to determine its durability. Compressive strength tests were conducted at different curing ages and the drying shrinkage of the grout was monitored for 180 days. The results indicate that the new grout is as good as a conventional grout but with added sustainable and economical benefits. The new grout can be used in masonry construction and can be used to alleviate the inadequate supply of affordable housing.

scholarly journals Investigation of zinc stannate synthesis using photoacoustic spectroscopy

2007 ◽  
Vol 39 (2) ◽  
pp. 153-160 ◽  
Author(s):  
T. Ivetic ◽  
M.V. Nikolic ◽  
P.M. Nikolic ◽  
V. Blagojevic ◽  
S. Djuric ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Ball Mill ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Amplitude Spectra ◽  
Scanning Electron

Mixtures of ZnO and SnO2 powders, with molar ratio of 2:1, were mechanically activated for 40, 80 and 160 minutes in a planetary ball mill. The resulting powders were compacted into pellets and non-isothermally sintered up to 1200?C with a heating rate of 5?C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained a correlation between thermal diffusivity and experimental conditions as well the samples microstructure characteristics was discussed. .

Microstructure Characteristics and Properties of 1561 Aluminum Alloy Weldments Processed by Different MIG Welding

2017 ◽  
Vol 893 ◽  
pp. 163-168
Author(s):  
Shan Guo Han ◽  
Shi Da Zheng ◽  
De Tao Cai ◽  
Yao Yong Yi ◽  
Zi Yi Luo
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Weld Zone ◽  
Base Material ◽  
Particle Phase ◽  
Mig Welding ◽  
Single Wire ◽  
Microstructure Characteristics ◽  
Different Characteristics ◽  
Scanning Electron

The mechanical properties and microstructural features of 1561 aluminum alloy weldments processed by single-wire MIG welding and CMT TWIN welding are investigated. The microstructure and mechanical properties of welded joints were studied by nondestructive testing, metallurgical test, scanning electron microscopy test, fatigue and tensile test. It is revealed that the welding efficiency of CMT TWIN welding is more than six times as much as single-wire MIG welding. It can be easy to find weld zone (WZ), fusion line (FL), heat affected zone (HAZ) and base metal (BM) with different characteristics in the metallographic specimen. In weld zone, the particle phase sizes are smaller than that of base material, but the densities of particle phase are increased. The sample fatigue strength of CMT TWIN welding is higher than the singe-wire MIG welding. It is suggested that the CMT TWIN welding has several advantages compared with single-wire MIG welding.

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