scholarly journals The Implication of Petrographic Characteristics on the Mechanical Behavior of Middle Eocene Limestone, 15th May City, Egypt

2020 ◽  
Vol 12 (22) ◽  
pp. 9710
Author(s):  
Abdelaziz El Shinawi ◽  
Peter Mésároš ◽  
Martina Zeleňáková
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Carbonate Rocks ◽  
Direct Relationship ◽  
Middle Eocene ◽  
Urban Expansion ◽  
Engineering Properties ◽  
Mechanical Parameters ◽  
Thin Sections ◽  
Limestone Bedrock

The construction purposes of carbonate rocks are considered a major aspect of using these bedrocks based on their mechanical behavior. Accordingly, the physical and mechanical characterization of Middle Eocene Limestone bedrock in the new urban area at the 15th May City, Egypt was studied to assess the suitability of the carbonate rocks for construction. This study has been carried out to investigate the effect of petrographic characteristics on mechanical properties. To achieve this objective, the intact 30 rock core samples from 15 boreholes were selected at different depths. Based on study of the selected samples in thin sections, the limestone in the area was classified as lime-mudstone, wackestone, and grainstone. Additionally, the uniaxial compressive strength (UCS) and Schmidt Rebound Hammer (Rn) were determined to detect the mechanical properties of the limestone bedrock. The measured parameters (UCS and Rn) demonstrated a high direct relationship with mudstone and a poor direct relationship with dolomite and high negative correlation with wackestone and grainstone. Therefore, the Middle Eocene Limestone bedrock is more durable and has medium-strength, which made it suitable for constructions. Regression analysis was performed to find out some linear relationship between mechanical properties (UCS) with petrographic characteristics. The study reveals significant positive correlation between UCS and Rn with mudstone in accordance higher values of regression coefficient (R2 = 0.91 and R2 = 0.036), and an inverse relationship of Rn with dolomite % (R2 = 0.89 and R2 = 0.02), respectively. Consequently, the strong confidence on the mechanical parameters opens the way for engineers to predict the mechanical parameters that are required for engineering properties of limestone for the urban expansion.

A TEM study of the interface between organic matrix and aragonite in a biological hard tissue, nacre

1992 ◽  
Vol 50 (2) ◽  
pp. 1024-1025
Author(s):  
Jun Liu ◽  
Katie E. Gunnison ◽  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Mechanical Properties ◽  
Ion Beam ◽  
Laminated Composite ◽  
Organic Matrix ◽  
Pearl Oyster ◽  
Interfacial Structure ◽  
Interfacial Region ◽  
Thin Sections ◽  
Organic Layers ◽  
Transmission Electron

The interfacial structure between the organic and inorganic phases in biological hard tissues plays an important role in controlling the growth and the mechanical properties of these materials. The objective of this work was to investigate these interfaces in nacre by transmission electron microscopy. The nacreous section of several different seashells -- abalone, pearl oyster, and nautilus -- were studied. Nacre is a laminated composite material consisting of CaCO3 platelets (constituting > 90 vol.% of the overall composite) separated by a thin organic matrix. Nacre is of interest to biomimetics because of its highly ordered structure and a good combination of mechanical properties. In this study, electron transparent thin sections were prepared by a low-temperature ion-beam milling procedure and by ultramicrotomy. To reveal structures in the organic layers as well as in the interfacial region, samples were further subjected to chemical fixation and labeling, or chemical etching. All experiments were performed with a Philips 430T TEM/STEM at 300 keV with a liquid Nitrogen sample holder.

MODELISATION DE L'INFLUENCE DU TRAITEMENT THERMIQUE SUR LES PROPRIETES MECANIQUES DES ALLIAGES ALUMINIUM-CUIVRE (Al-Cu)

2015 ◽  
Vol 10 (2) ◽  
pp. 2753-2761
Author(s):  
Saad El Madani ◽  
S. ELHAMZI ◽  
A. IBNLFASSI ◽  
L. ZERROUK ◽  
O. BEN LENDA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Solidification Process ◽  
Traitement Thermique ◽  
Homogenization Process ◽  
Fundamental Reason ◽  
Segregation Phenomenon ◽  
Proprietes Mecaniques ◽  
Cooling Velocity ◽  
Copper Effect

In order to master and improve the quality and properties of the final products, the major industrial challenge lies in the possibility of controlling the morphology, size of microstructures that reside within the molded pieces, as well as their defects; this is the fundamental reason according to which we are more and more interested in mastering the growth and germination of such alloys, as well as the developing structures, at the time of solidification process. The modeling reveals as a valuable aid in the mastery of the formation of such heterogeneousness: segregation cells that are incompatible with industrial requirements.   The whole work focuses upon the modeling of the segregation phenomenon of the four hypoeutectic alloys, Al1%Cu, Al2%Cu, Al3%Cu et Al4%Cu, as well as the copper effect upon certain mechanical properties of aluminum. Usually, the microstructure and mechanical behavior of such alloys as Al-Cu are directly influenced by some parameters such as composition, cooling velocity and homogenization process.

scholarly journals Experimental and Numerical Evaluation of Mechanical Properties of 3D-Printed Stainless Steel 316L Lattice Structures

2021 ◽  
Author(s):  
M. Carraturo ◽  
G. Alaimo ◽  
S. Marconi ◽  
E. Negrello ◽  
E. Sgambitterra ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Mechanical Behavior ◽  
Numerical Simulations ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Lattice Structures ◽  
Stainless Steel 316L ◽  
Research Attention ◽  
Octet Truss

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.

scholarly journals Effects of Different Types of Fibers on the Physical and Mechanical Properties of MICP-Treated Calcareous Sand

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 268
Author(s):  
Jitong Zhao ◽  
Huawei Tong ◽  
Yi Shan ◽  
Jie Yuan ◽  
Qiuwang Peng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Glass Fiber ◽  
Physical And Mechanical Properties ◽  
Polyester Fiber ◽  
Engineering Properties ◽  
Fiber Types ◽  
Calcite Precipitation ◽  
Calcareous Sand ◽  
Hemp Fiber

Microbial-induced calcite precipitation (MICP) has been a promising method to improve geotechnical engineering properties through the precipitation of calcium carbonate (CaCO3) on the contact and surface of soil particles in recent years. In the present experiment, water absorption and unconfined compressive strength (UCS) tests were carried out to investigate the effects of three different fiber types (glass fiber, polyester fiber, and hemp fiber) on the physical and mechanical properties of MICP-treated calcareous sand. The fibers used were at 0%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, and 0.40% relative to the weight of the sand. The results showed that the failure strain and ductility of the samples could be improved by adding fibers. Compared to biocemented sand (BS), the water absorption of these three fiber-reinforced biocemented sands were, respectively, decreased by 11.60%, 21.18%, and 7.29%. UCS was, respectively, increased by 24.20%, 60.76%, and 6.40%. Polyester fiber produced the best effect, followed by glass fiber and hemp fiber. The optimum contents of glass fiber and polyester fiber were 0.20% and 0.25%, respectively. The optimum content of hemp fiber was within the range of 0.20–0.25%. Light-emitting diode (LED) microscope and scanning electron microscope (SEM) images lead to the conclusion that only a little calcite precipitation had occurred around the hemp fiber, leading to a poor bonding effect compared to the glass and polyester fibers. It was therefore suggested that polyester fiber should be used to improve the properties of biocemented sand.

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

scholarly journals Decoupling of Mechanical and Transport Properties in Organogels via Solvent Variation

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 61
Author(s):  
Kenneth P. Mineart ◽  
Cameron Hong ◽  
Lucas A. Rankin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Transdermal Drug Delivery ◽  
Triblock Copolymer ◽  
Polymer Concentration ◽  
Mineral Oil ◽  
Solute Diffusion ◽  
Oil Viscosity ◽  
Chain Entanglement ◽  
Mineral Oils

Organogels have recently been considered as materials for transdermal drug delivery media, wherein their transport and mechanical properties are among the most important considerations. Transport through organogels has only recently been investigated and findings highlight an inextricable link between gels’ transport and mechanical properties based upon the formulated polymer concentration. Here, organogels composed of styrenic triblock copolymer and different aliphatic mineral oils, each with a unique dynamic viscosity, are characterized in terms of their quasi-static uniaxial mechanical behavior and the internal diffusion of two unique solute penetrants. Mechanical testing results indicate that variation of mineral oil viscosity does not affect gel mechanical behavior. This likely stems from negligible changes in the interactions between mineral oils and the block copolymer, which leads to consistent crosslinked network structure and chain entanglement (at a fixed polymer concentration). Conversely, results from diffusion experiments highlight that two penetrants—oleic acid (OA) and aggregated aerosol-OT (AOT)—diffuse through gels at a rate inversely proportional to mineral oil viscosity. The inverse dependence is theoretically supported by the hydrodynamic model of solute diffusion through gels. Collectively, our results show that organogel solvent variation can be used as a design parameter to tailor solute transport through gels while maintaining fixed mechanical properties.

scholarly journals Understanding the Barrier and Mechanical Behavior of Different Nanofillers in Chitosan Films for Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 721 ◽  
Author(s):  
João Pires ◽  
Camila Damásio de Paula ◽  
Victor Gomes Lauriano Souza ◽  
Ana Luísa Fernando ◽  
Isabel Coelhoso
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Food Packaging ◽  
Scientific Research ◽  
Barrier Properties ◽  
Plastic Pollution ◽  
Functional Attributes ◽  
Chitosan Films ◽  
Commercial Applications ◽  
Innovative Techniques

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to its unmatched biological and functional attributes, chitosan (Ch) has been substantially explored and employed as a biopolymeric matrix. Nevertheless, the hydrophilicity and the weak mechanical properties associated with this biopolymer represent a significant intrinsic restriction to its implementation into some commercial applications, namely, in food packaging industries. Distinct methodologies have been utilized to upgrade the mechanical and barrier properties of Ch, such as using organic or inorganic nanofillers, crosslinkers, or blends with other polymers. This review intends to analyze the most recent works that combine the action of different nanoparticle types with Ch films to reinforce their mechanical and barrier properties.

Microstructure and Mechanical Properties of Ti-6Al-4V Manufactured by SLM

2015 ◽  
Vol 651-653 ◽  
pp. 677-682 ◽  
Author(s):  
Anatoliy Popovich ◽  
Vadim Sufiiarov ◽  
Evgenii Borisov ◽  
Igor Polozov
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Phase Composition ◽  
Mechanical Behavior ◽  
Ductile Fracture ◽  
Elevated Temperatures ◽  
Initial Material ◽  
Laser Melting ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The article presents results of a study of phase composition and microstructure of initial material and samples obtained by selective laser melting of titanium-based alloy, as well as samples after heat treatment. The effect of heat treatment on microstructure and mechanical properties of specimens was shown. It was studied mechanical behavior of manufactured specimens before and after heat treatment at room and elevated temperatures as well. The heat treatment allows obtaining sufficient mechanical properties of material at room and elevated temperatures such as increase in ductility of material. The fractography of samples showed that they feature ductile fracture with brittle elements.

scholarly journals Mechanical behavior of frozen soil improved with sulphoaluminate cement and its microscopic mechanism

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhenhua Yin ◽  
Hu Zhang ◽  
Jianming Zhang ◽  
Mingtang Chai
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Soil Improvement ◽  
Particle Size Analysis ◽  
Frozen Soil ◽  
Size Analysis ◽  
Permafrost Soil ◽  
Compression Tests ◽  
Microscopic Mechanism ◽  
Sulphoaluminate Cement

Abstract The foundation of constructions built in the permafrost areas undergo considerable creeping or thawing deformation because of the underlying ice-rich permafrost. Soil improvement may be of advantage in treating ice-rich permafrost at shallow depth. Sulphoaluminate cement was a potential material to improve frozen soil. Simultaneously, two other cements, ordinary Portland cement and Magnesium phosphate cement were selected as the comparison. The mechanical behavior of modified frozen soil was studied with thaw compression tests and unconfined compression strength tests. Meanwhile, the microscopic mechanism was explored by field emission scanning electron microscopy, particle size analysis and X-ray diffractometry. The results showed Sulphoaluminate cement was useful in reducing the thaw compression deformation and in enhancing the strength of the frozen soil. The improvement of the mechanical behavior depended mainly on two aspects: the formation of structural mineral crystals and the agglomeration of soil particles. The two main factors contributed to the improvement of mechanical properties simultaneously. The thicker AFt crystals result in a higher strength and AFt plays an important role in improving the mechanical properties of frozen soils.The study verified that Sulphoaluminate cement was an excellent stabilizer to improve ice-rich frozen soils.

Sign in / Sign up

Export Citation Format

Share Document