Search results for: plastic starch composite

Authors: J. C. M. Santos, J. C. A. Sousa, A. J. Rubio, L. S. Soletti, F. Gasparotto, N. U. Yamaguchi

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Magnetic graphene has received widespread attention for their capability of water and wastewater treatment, which has been attracted many researchers in this field. A bibliometric analysis based on the Web of Science database was employed to analyze the global scientific outputs of magnetic graphene for water treatment until the present time (2012 to 2017), to improve the understanding of the research trends. The publication year, place of publication, institutes, funding agencies, journals, most cited articles, distribution outputs in thematic categories and applications were analyzed. Three major aspects analyzed including type of pollutant, treatment process and composite composition have further contributed to revealing the research trends. The most relevant research aspects of the main technologies using magnetic graphene for water treatment were summarized in this paper. The results showed that research on magnetic graphene for water treatment goes through a period of decline that might be related to a saturated field and a lack of bibliometric studies. Thus, the result of the present work will lead researchers to establish future directions in further studies using magnetic graphene for water treatment.

Keywords: composite, graphene oxide, nanomaterials, scientometrics

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Authors: Julia Cristina Bonaldo, Christophe L. Martin, Severine Romero Baivier, Stephane Mazerat

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Alumina refractories are commonly used in steel and foundry industries. These refractories are prepared through a powder metallurgy route. They are a mixture of hard alumina particles and graphite platelets embedded into a soft carbonic matrix (binder). The powder can be cold pressed isostatically or uniaxially, depending on the application. The compact is then fired to obtain the final product. The quality of the product is governed by the microstructure of the composite and by the process parameters. The compaction behavior and the mechanical properties of the fired product depend greatly on the amount of each phase, on their morphology and on the initial microstructure. In order to better understand the link between these parameters and the macroscopic behavior, we use the Discrete Element Method (DEM) to simulate the compaction process and the fracture behavior of the fired composite. These simulations are coupled with well-designed experiments. Four mixes with various amounts of Al₂O₃ and binder were tested both experimentally and numerically. In DEM, each particle is modelled and the interactions between particles are taken into account through appropriate contact or bonding laws. Here, we model a bimodal mixture of large Al₂O₃ and small Al₂O₃ covered with a soft binder. This composite is itself mixed with graphite platelets. X-ray tomography images are used to analyze the morphologies of the different components. Large Al₂O₃ particles and graphite platelets are modelled in DEM as sets of particles bonded together. The binder is modelled as a soft shell that covers both large and small Al₂O₃ particles. When two particles with binder indent each other, they first interact through this soft shell. Once a critical indentation is reached (towards the end of compaction), hard Al₂O₃ - Al₂O₃ contacts appear. In accordance with experimental data, DEM simulations show that the amount of Al₂O₃ and the amount of binder play a major role for the compaction behavior. The graphite platelets bend and break during the compaction, also contributing to the macroscopic stress. Firing step is modeled in DEM by ascribing bonds to particles which contact each other after compaction. The fracture behavior of the compacted mixture is also simulated and compared with experimental data. Both diametrical tests (Brazilian tests) and triaxial tests are carried out. Again, the link between the amount of Al₂O₃ particles and the fracture behavior is investigated. The methodology described here can be generalized to other particulate materials that are used in the ceramic industry.

Keywords: cold compaction, composites, discrete element method, refractory materials, x-ray tomography

Procedia PDF Downloads 141

Authors: E. Wairimu Mwangi, Daniel Sarpong

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Background: Access to effective antiretroviral therapy in the United States has resulted in the rise in longevity in people living with HIV (PLHIV). Despite the progress, women living with HIV (WLWH) experience increasing rates of cardiometabolic disorders compared with their HIV-negative counterparts. Studies focusing on the predictors of metabolic disorders in this population have largely focused on the composite measure of metabolic syndrome (METs). This study seeks to identify the predictors of composite and individual METs factors in a nationally representative sample of WLWH. In particular, the study also examines the role of food security in predicting METs. Methods: The study comprised 1800 women, a subset of participants from the Women’s Interagency HIV Study (WIHS). The primary exposure variable, food security, was measured using the U.S. 10-item Household Food Security Survey Module. The outcome measures are the five metabolic syndrome indicators (elevated blood pressure [systolic BP > 130 mmHg and diastolic BP ≥ 85 mmHg], elevated fasting glucose [≥ 110 mg/dL], elevated fasting triglyceride [≥ 150 mg/dL], reduced HDL cholesterol [< 50 mg/dL], and waist circumference > 88 cm) and the composite measure - Metabolic Syndrome (METs) Status. Each metabolic syndrome indicator was coded one if yes and 0 otherwise. The values of the five indicators were summed, and participants with a total score of 3 or greater were classified as having metabolic syndrome. Participants classified as having metabolic syndrome were assigned a code of 1 and 0 otherwise for analysis. The covariates accounted for in this study fell into sociodemographic factors and behavioral and health characteristics. Results: The participants' mean (SD) age was 47.1 (9.1) years, with 71.4% Blacks and 10.9% Whites. About a third (33.1%) had less than a high school (HS) diploma, 60.4% were married, 32.8% were employed, and 53.7% were low-income. The prevalence of worst dietary diversity, low, moderate, and high food security were 24.1%, 26.6%, 17.0%, and 56.4%, respectively. The correlate profile of the five individual METs factors plus the composite measure of METs differ significantly, with METs based on HDL having the most correlates (Age, Education, Drinking Status, Low Income, Body Mass Index, and Health Perception). Additionally, metabolic syndrome based on waist circumference was the only metabolic factor where food security was significantly correlated (Food Security, Age, and Body Mass Index). Age was a significant predictor of all five individual METs factors plus the composite METs measure. Except for METs based on Fasting Triglycerides, body mass index (BMI) was a significant correlate of the various measures of metabolic syndrome. Conclusion: High-density Lipoprotein (HDL) cholesterol significantly correlated with most predictors. BMI was a significant predictor of all METs factors except Fasting Triglycerides. Food insecurity, the primary predictor, was only significantly associated with waist circumference.

Keywords: blood pressure, food insecurity, fasting glucose, fasting triglyceride, high-density lipoprotein, metabolic syndrome, waist circumference, women living with HIV

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Authors: T. A. Sakr, Hanaa E. Abd-El-Mottaleb

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Outrigger-braced wall systems are commonly used to provide high rise buildings with the required lateral stiffness for wind and earthquake resistance. The existence of outriggers adds to the stiffness and strength of walls as reported by several studies. The effects of different parameters on the elasto-plastic dynamic behavior of outrigger-braced wall systems to earthquakes are investigated in this study. Parameters investigated include outrigger stiffness, concrete strength, and reinforcement arrangement as the main design parameters in wall design. In addition to being significant to the wall behavior, such parameters may lead to the change of failure mode and the delay of crack propagation and consequently failure as the wall is excited by earthquakes. Bi-linear stress-strain relation for concrete with limited tensile strength and truss members with bi-linear stress-strain relation for reinforcement were used in the finite element analysis of the problem. The famous earthquake record, El-Centro, 1940 is used in the study. Emphasis was given to the lateral drift, normal stresses and crack pattern as behavior controlling determinants. Results indicated significant effect of the studied parameters such that stiffer outrigger, higher grade concrete and concentrating the reinforcement at wall edges enhance the behavior of the system. Concrete stresses and cracking behavior are sigbificantly enhanced while lesser drift improvements are observed.

Keywords: outrigger, shear wall, earthquake, nonlinear

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Authors: Nioushasadat Haji Seyed Javadi, Ailar Hajimohammadi, Nasser Khalili

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The common method to improve the performance of asphalt binders is through modification. The utilization of recycled plastics for asphalt modification has been the subject of research studies due to their environmental and economic benefits over using commercial polymers. Polypropylene (PP) is one of the most available recycled plastics in Australia. Unlike other plastics, its contamination with other plastics during the recycling process is negligible. Therefore, the quality of recycled plastic is high, which makes it a good candidate for road construction applications. To assess its effectiveness for bitumen modification, three different grades of PP were selected. The PP grades were compared for blendability with bitumen, and the best suitable grade was chosen for further studies. The PP-modified bitumen and the base bitumen were then compared through physical and rheological properties. The stability of the PP-modified bitumen at elevated temperatures was measured, and the morphology of the samples before and after the storage stability was characterized by fluorescent microscopy. The results showed that PP had a significant influence on reducing the penetration and increasing the viscosity and the rutting resistance of the virgin bitumen. Storage stability test results indicated that the difference between the softening point of the top and bottom section of the tube sample is below the defined limit, which means the PP-modified bitumen is storage stable. However, the fluorescence microscopy results showed that the distribution of the PP particles in the bitumen matrix in the top and bottom sections of the tube are significantly different, which is an indicator of poor storage stability.

Keywords: polypropylene, waste plastic, bitumen, road pavements, storage stability, fluorescent microscopy, morphology

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Authors: Y. Mateyshina, A.Ulihin, N.Uvarov

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Electrolytes with different type of charge carrier can find widely application in different using, e.g. sensors, electrochemical equipments, batteries and others. One of important components ensuring stable functioning of the equipment is electrolyte. Electrolyte has to be characterized by high conductivity, thermal stability, and wide electrochemical window. In addition to many advantageous characteristic for liquid electrolytes, the solid state electrolytes have good mechanical stability, wide working range of temperature range. Thus search of new system of solid electrolytes with high conductivity is an actual task of solid state chemistry. Families of alkali perchlorates and nitrates have been investigated by us earlier. In literature data about transport properties of alkali nitrites are absent. Nevertheless, alkali nitrites MeNO2 (Me= Li+, Na+, K+, Rb+ and Cs+), except for the lithium salt, have high-temperature phases with crystal structure of the NaCl-type. High-temperature phases of nitrites are orientationally disordered, i.e. non-spherical anions are reoriented over several equivalents directions in the crystal lattice. Pure lithium nitrite LiNO2 is characterized by ionic conductivity near 10-4 S/cm at 180°C and more stable as compared with lithium nitrate and can be used as a component for synthesis of composite electrolytes. In this work composite solid electrolytes in the binary system LiNO2 - A (A= MgO, -Al2O3, Fe2O3, CeO2, SnO2, SiO2) were synthesized and their structural, thermodynamic and electrical properties investigated. Alkali nitrite was obtained by exchange reaction from water solutions of barium nitrite and alkali sulfate. The synthesized salt was characterized by X-ray powder diffraction technique using D8 Advance X-Ray Diffractometer with Cu K radiation. Using thermal analysis, the temperatures of dehydration and thermal decomposition of salt were determined.. The conductivity was measured using a two electrode scheme in a forevacuum (6.7 Pa) with an HP 4284A (Precision LCR meter) in a frequency range 20 Hz < ν < 1 MHz. Solid composite electrolytes LiNO2 - A A (A= MgO, -Al2O3, Fe2O3, CeO2, SnO2, SiO2) have been synthesized by mixing of preliminary dehydrated components followed by sintering at 250°C. In the series of nitrite of alkaline metals Li+-Cs+, the conductivity varies not monotonically with increasing radius of cation. The minimum conductivity is observed for KNO2; however, with further increase in the radius of cation in the series, the conductivity tends to increase. The work was supported by the Russian Foundation for Basic research, grant #14-03-31442.

Keywords: conductivity, alkali nitrites, composite electrolytes, transport properties

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Authors: M. Kharrat, G. Moreau, Z. Aboura

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The latest advances in the weaving industry, combined with increasingly sophisticated means of materials processing, have made it possible to produce complex 3D composite structures. Mainly used in aeronautics, composite materials with 3D architecture offer better mechanical properties than 2D reinforced composites. Nevertheless, these materials require a good understanding of their behavior. Because of the complexity of such materials, the damage mechanisms are multiple, and the scenario of their appearance and evolution depends on the nature of the exerted solicitations. The AE technique is a well-established tool for discriminating between the damage mechanisms. Suitable sensors are used during the mechanical test to monitor the structural health of the material. Relevant AE-features are then extracted from the recorded signals, followed by a data analysis using pattern recognition techniques. In order to better understand the damage scenarios of interlock composite materials, a multi-instrumentation was set-up in this work for tracking damage initiation and development, especially in the vicinity of the first significant damage, called macro-damage. The deployed instrumentation includes video-microscopy, Digital Image Correlation, Acoustic Emission (AE) and micro-tomography. In this study, a multi-variable AE data analysis approach was developed for the discrimination between the different signal classes representing the different emission sources during testing. An unsupervised classification technique was adopted to perform AE data clustering without a priori knowledge. The multi-instrumentation and the clustered data served to label the different signal families and to build a learning database. This latter is useful to construct a supervised classifier that can be used for automatic recognition of the AE signals. Several materials with different ingredients were tested under various solicitations in order to feed and enrich the learning database. The methodology presented in this work was useful to refine the damage threshold for the new generation materials. The damage mechanisms around this threshold were highlighted. The obtained signal classes were assigned to the different mechanisms. The isolation of a 'noise' class makes it possible to discriminate between the signals emitted by damages without resorting to spatial filtering or increasing the AE detection threshold. The approach was validated on different material configurations. For the same material and the same type of solicitation, the identified classes are reproducible and little disturbed. The supervised classifier constructed based on the learning database was able to predict the labels of the classified signals.

Keywords: acoustic emission, classifier, damage mechanisms, first damage threshold, interlock composite materials, pattern recognition

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Authors: Vighnesh Daas, David B. Tann, Mahmood Datoo

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The incorporation of recycled plastic fibres in concrete as reinforcement is a potential sustainable alternative for replacement of ordinary steel bars. It provides a scope for waste reduction and re-use of plastics in the construction industry on a large scale. Structural use of fibre reinforced concrete is limited to short span members and low reliability classes. In this study, recycled carpet fibres made of 95% polypropylene with length of 45mm were used for experimental investigations. The performance of recycled polypropylene fibres under structural loading has been compared with commercially available virgin fibres at low volume fractions of less than 1%. A series of 100 mm cubes and 125x200x2000 mm beams were used to conduct strength tests in bending and compression to measure the influence of type and volume of fibres on the structural behaviour of fibre reinforced concrete beams. The workability of the concrete mix decreased as a function of fibre content and resulted in a modification of the mix design. The beams failed in a pseudo-ductile manner with an enhanced bending capacity. The specimens showed significant improvement in the post-cracking behaviour and load carrying ability as compared to conventional reinforced concrete members. This was associated to the binding properties of the fibres in the concrete matrix. With the inclusion of fibres at low volumes of 0-0.5%, there was reduction in crack sizes and deflection. This study indicates that the inclusion of recycled polypropylene fibres at low volumes augments the structural behaviour of concrete as compared to conventional reinforced concrete as well as virgin fibre reinforced concrete.

Keywords: fibre reinforced concrete, polypropylene, recycled, strength

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Authors: Oscar Kallay

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Objective: This study compares the sustainability, financial implications, and surgical efficiency of two phacoemulsification cassette systems for cataract surgery: a machine with single-use cassettes and another with daily, reusable ones. Methods: The observational study involves retrospective cataract surgery data collection at the Centre Médical de l'Alliance, Braine-L’alleud, Belgium, a tertiary eye care center. Information on cassette weight, quantities, and transport volume was obtained from routine procedures and purchasing records. The costs for each machine were calculated by reviewing the invoices received from the accounting department. Results: We found significant differences across comparisons. The reusable cassette machine, when compared to the single-use machine, used 306.7 kg less plastic (75.3% reduction), required 2,494 cubic meters less storage per 1000 surgeries (67.7% decrease), and cost €54.16 less per 10 procedures (16.9% reduction). The machine with daily reusable cassettes also exhibited a 7-minute priming time advantage for 10 procedures, reducing downtime between cases. Conclusions: Our findings underscore the benefits of adopting reusable cassette systems: reduced plastic consumption, storage volume, and priming time, as well as enhanced efficiency and cost savings. Healthcare professionals and institutions are encouraged to embrace environmentally conscious initiatives. The use of reusable cassette systems for cataract surgeries offers a pathway to sustainable practices.

Keywords: cataract, epidemiolog, surgery treatment, lens and zonules, public health

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Authors: Lidan Wang, Shuyuan Zhao, Jianxin He

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In this paper, graphene-doped copper indium disulfide (rGO+CuInS2) composite nanofibers were fabricated via electrospinning, in situ synthesis, and carbonization, using polyvinyl pyrrolidone (PVP), copper dichloride (CuCl2), indium trichloride (InCl3), thiourea (C2H5NS) and graphene oxide nanosheets (Go) as the precursor solution for electrospinning. The average diameter of rGO+CuInS2 nanofibers were about 100 nm, and graphene nanosheets anchored with chalcopyrite CuInS2 nanocrystals 8-15 nm in diameter were overlapped and embedded, aligning along the fiber axial direction. The DSSC with a rGO+CuInS2 counter electrode exhibits a power conversion efficiency of 5.93%; better than the corresponding values for a DSSC with a CuInS2 counter electrode, and comparable to that of a reference DSSC with a Pt counter electrode. The excellent photoelectric performance of the rGO+CuInS2 counter electrode was attributed to its high specific surface area, which facilitated permeation of the liquid electrolytes, promoted electron and ion transfer and provided numerous catalytically active sites for the oxidation reaction of the electrolytic (I- /I3-).

Keywords: dye-sensitized solar cells, counter electrode, electrospinning, graphene

Procedia PDF Downloads 460

Authors: M. S. Kamarulzaman, N. A. Muhamad, N. A. M. Jamail, M. A. M. Piah, N. F. Kasri

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Insulation for high voltage application that has been service for a very long time is subjected to several types of degradation. The degradation can lead to premature breakdown and definitely will spent highly cost to replace the cable. Thus, there are many research on nano composite material get serious attention attention due to their abilities to enhance electrical performance by addition of nano filler. In this paper, water absorption of Low Linear Density Polyethyelene (LLDPE) with different amount of nano filler added is studied. This study is necessary to be conducted since most of electrical apparatus such as cable insulation are dominant used especially in high voltage application. The cable insulation are continuously exposed in uncontrolled environment may suffer degradation process. Three type of nano fillers, was used in this study are: Silicon dioxide (SiO2), Titanium dioxide (TiO2) and Monmorillonite (MMT). The percentage absorption of water was measured by weighted using high precision scales for absorption process up to 92 days. Experimental result demonstrate that SiO2 absorb less water than other filler while, the MMT has hydrophilic properties which it absorbs more water compare to another sample.

Keywords: nano composite, nano filler, water absorption, hydrophilic properties

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Authors: Benny Alexander, Ikhlashia N. Fadhilah, Muhammad R. Pasha, Michelle Julia, Anne Z. Syahrial

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Brake shoe is a component that serves to reduce speed or stop the train's speed by utilizing the friction force. Generally, the material used as a brake shoe is cast iron, where cast iron itself is a heavy, expensive, and easily worn material. Aluminum matrix composites are one of candidates for the cast iron replacement material as the basic material for brake shoe. The matrix in the composite used is Aluminum AC4B. Reinforcement used in aluminum matrix composites is nano-alumina, where the use of nano-alumina of 0.25%, 0.3%, 0.35%, 0.4%, and 0.5% volume fraction will be tested. The sample is made using the stir casting method; then, it will be tested mechanically. The use of nano-alumina as a reinforcement will increase the strength of the matrix. SEM (scanning electron microscopy) testing is used to test the distribution of reinforcing particles due to stirring. Therefore, the addition of nano-alumina will improve AC4B aluminum matrix composites.

Keywords: aluminium matrix composites, brake shoe application, stir casting, nano-alumina

Procedia PDF Downloads 137

Authors: Praveen K. Khatri, Neha Karanwal, Savita Kaul, Suman L. Jain

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Conversion of biomass through green chemical routes is of great industrial importance as biomass is considered to be most widely available inexpensive renewable resource that can be used as a raw material for the production of bio fuel and value-added organic products. In this regard, acid catalyzed dehydration of biomass derived pentose sugar (mainly D-xylose) to furfural is a process of tremendous research interest in current scenario due to the wider industrial applications of furfural. Furfural is an excellent organic solvent for refinement of lubricants and separation of butadiene from butene mixture in synthetic rubber fabrication. In addition it also serve as a promising solvent for many organic materials, such as resins, polymers and also used as a building block for synthesis of various valuable chemicals such as furfuryl alcohol, furan, pharmaceutical, agrochemicals and THF. Here in a sulfonated polymer impregnated carbon composite solid acid catalyst (P-C-SO3H) was prepared by the pyrolysis of a polymer matrix impregnated with glucose followed by its sulfonation and used for the dehydration of xylose to furfural. The developed catalyst exhibited excellent activity and provided almost quantitative conversion of xylose with the selective synthesis of furfural. The higher catalytic activity of P-C-SO3H may be due to the more even distribution of polycyclic aromatic hydrocarbons generated from incomplete carbonization of glucose along the polymer matrix network, leading to more available sites for sulfonation which resulted in greater sulfonic acid density in P-C-SO3H as compared to sulfonated carbon catalyst (C-SO3H). In conclusion, we have demonstrated sulfonated polymer impregnated carbon composite (P-C-SO3H) as an efficient and selective solid acid catalyst for the dehydration of xylose to furfural. After completion of the reaction, the catalyst was easily recovered and reused for several runs without noticeable loss in its activity and selectivity.

Keywords: Solid acid , Biomass conversion, Xylose Dehydration, Heterogeneous catalyst

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Authors: Shanawaz Patil, Mohamed Haneef, K. S. Narayanaswamy

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In the recent years, aluminum metal matrix composites were most widely used, which are finding wide applications in various field such as automobile, aerospace defense etc., due to their outstanding mechanical properties like low density, light weight, exceptional high levels of strength, stiffness, wear resistance, high temperature resistance, low coefficient of thermal expansion and good formability. In the present work, an effort is made to study the effect of heat treatment on mechanical properties of aluminum 7075 alloy reinforced with constant weight percentage of naturally occurring mineral beryl and varying weight percentage of graphene. The hybrid composites are developed with 0.5 wt. %, 1wt.%, 1.5 wt.% and 2 wt.% of graphene and 6 wt.% of beryl  by stir casting liquid metallurgy route. The cast specimens of unreinforced aluminum alloy and hybrid composite samples were prepared for heat treatment process and subjected to solutionizing treatment (T6) at a temperature of 490±5 ^oC for 8 hours in a muffle furnace followed by quenching in boiling water. The microstructure analysis of as cast and heat treated hybrid composite specimens are examined by scanning electron microscope (SEM). The tensile test and hardness test of unreinforced aluminum alloy and hybrid composites are examined. The wear behavior is examined by pin-on disc apparatus. The results of as cast specimens and heat treated specimens were compared. The heat treated Al7075-Beryl-Graphene hybrid composite had better properties and significantly improved the ultimate tensile strength, hardness and reduced wear loss when compared to aluminum alloy and  as cast hybrid composites.

Keywords: beryl, graphene, heat treatment, mechanical properties

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Authors: Mohammed Berka, Khaled Merit

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Recent works on microwave filters show that the constituent materials such filters are very important in the design and realization. Several solutions have been proposed to improve the qualities of filtering. In this paper, we propose a new dual band-pass filter based on the coupling of a composite (CRLH) coplanar waveguide with complementary split ring resonators (CSRRs). The (CRLH) CPW is composed of two resonators, each one has an interdigital capacitor (CID) and two short-circuited stubs parallel to top ground plane. On the lower ground plane, we use defected ground structure technology (DGS) to engrave two (CSRRs) offered with different shapes and dimensions. Between the top ground plane and the substrate, we place a ferrite layer to control the electromagnetic coupling between (CRLH) CPW and (CSRRs). The global filter that has coplanar access will have a dual band-pass behavior around the magnetic resonances of (CSRRs). Since there’s no scientific or experimental result in the literature for this kind of complicated structure, it was necessary to perform simulation using HFSS Ansoft designer.

Keywords: complementary split ring resonators, coplanar waveguide, ferrite, filter, stub.

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Authors: Heeyoung Lee, Woosung Bin, Kangseog Seo, Hyojeong Yun, Zuog An

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Recently, a new continuous bridge system has been proposed to increase the space under the bridge and to improve aesthetic aspect of the urban area. The main feature of the proposed bridge is to connect steel I-girders and coping by means of prestressed high-strength steel bars and steel plate. The proposed bridge is able to lower the height of the bridge to ensure the workability and efficiency through a reduction of the cost of road construction. This study presents the experimental result of the full-scale connection between steel I-girders and coping under the negative bending moment. The composite behavior is thoroughly examined and discussed under the specific load levels such as service load, factored load and crack load. Structural response showed full composite action until the final load level because no relative displacement between coping and girder was observed. It was also found prestressing force into high-strength bars was able to control tensile stresses of deck slab. This indicated that cracks in deck slab can be controlled by above-mentioned prestressing force.

Keywords: coping, crack, integrated bridge, full-scale test

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Authors: Mohamed S. Selim, Nesreen A. Fatthallah, Shimaa A. Higazy, Zhifeng Hao, Xiang Chen

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After the prohibition of tin-based fouling-prevention coatings in 2003, the researchers were directed toward eco-friendly coatings. Because of their nonstick, environmental, and economic benefits, foul-release nanocoatings have received a lot of attention. They use physical anti-adhesion terminology to deter any fouling attachment.Natural bioinspired surfaces have micro/nano-roughness and low surface free energy features, which may inspire the design of dynamic antifouling coatings. Graphene-based nanocomposite surfaces were designed to combat marine-fouling adhesion with ecological as well as eco-friendly effects rather than biocidal solutions. Polymer–graphenenanofiller hybrids are a novel class of composite materials in fouling-prevention applications. The controlled preparation of nanoscale orientation, arrangement, and direction along the composite building blocks would result in superior fouling prohibition. This work representsfoul-release nanocomposite top coats for marine coating applications with superhydrophobicity, surface inertness against fouling adherence, cost-effectiveness, and increased lifetime.

Keywords: foul-release nanocoatings, graphene-based nanocomposite, polymer, nanofillers

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Authors: Anthony Chidi Ezika, Gbolahan Joseph Adekoya, Emmanuel Rotimi Sadiku, Yskandar Hamam, Suprakas Sinha Ray

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High-energy-density polymer/ceramic composites require a high breakdown strength and dielectric constant. Interface polarization and electric percolation are responsible for the high dielectric constant. In order to create composite dielectrics, high conductivity ceramic particles are combined with polymers to increase the dielectric constant. In this study, bonding and the non-uniform distribution of charges in the ceramic/ceramic interface zone are investigated using density functional theory (DFT) modeling. This non-uniform distribution of charges is intended to improve the ceramic/ceramic interface's dipole polarization (dielectric response). The interfacial chemical bond formation can also improve the structural stability of the hybrid filler and, consequently, of the composite films. To comprehend the electron-transfer process, the density of state and electron localization function of the PPy with hybrid fillers are also studied. The polymer nanocomposite is anticipated to provide a suitable dielectric response for energy storage applications.

Keywords: energy storage, V₂C/ ZnS hybrid, polypyrrole, MXene, nanocomposite, dielectric

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Authors: Min Ye Koo, Gyo Woo Lee

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In this study, epoxy composite specimens reinforced with multi-walled carbon nanotube filler were fabricated using shear mixer and ultra-sonication processor. The mechanical and thermal properties of the fabricated specimens were measured and evaluated. From the electron microscope images and the results from the measurements of tensile strengths, the specimens having 0.6 wt% nanotube content show better dispersion and higher strength than those of the other specimens. The Young’s moduli of the specimens increased as the contents of the nanotube filler in the matrix were increased. The specimen having a 0.6 wt% nanotube filler content showed higher thermal conductivity than that of the other specimens. While, in the measurement of thermal expansion, specimens having 0.4 and 0.6 wt% filler contents showed a lower value of thermal expansion than that of the other specimens. On the basis of the measured and evaluated properties of the composites, we believe that the simple and time-saving fabrication process used in this study was sufficient to obtain improved properties of the specimens.

Keywords: carbon nanotube filler, epoxy composite, ultra-sonication, shear mixer, mechanical property, thermal property

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Authors: Shingo Murakami, Shinichi Enoki

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In structures, stress concentration is a factor of fatigue fracture. Basically, the stress concentration is a phenomenon that should be avoided. However, it is difficult to avoid the stress concentration. Therefore, relaxation of the stress concentration is important. The stress concentration arises from notches and circular holes. There is a relaxation method that a composite patch covers a notch and a circular hole. This relaxation method is used to repair aerial wings, but it is not systematized. Composites are more expensive than single materials. Accordingly, we propose the relaxation method that a single material patch covers a notch and a circular hole, and aim to systematize this relaxation method. We performed FEA (Finite Element Analysis) about an object by using a three-dimensional FEA model. The object was that a patch adheres to a plate with a circular hole. And, a uniaxial tensile load acts on the patched plate with a circular hole. In the three-dimensional FEA model, it is not easy to model the adhesion layer. Basically, the yield stress of the adhesive is smaller than that of adherents. Accordingly, the adhesion layer gets to plastic deformation earlier than the adherents under the yield stress of adherents. Therefore, we propose the three-dimensional FEA model which is applied a nonlinear elastic region to the adhesion layer. The nonlinear elastic region was calculated by a bilinear approximation. We compared the analysis results with the tensile test results to confirm whether the analysis model has usefulness. As a result, the analysis results agreed with the tensile test results. And, we confirmed that the analysis model has usefulness. As a result that the three-dimensional FEA model was used to the analysis, it was confirmed that an out-of-plane deformation occurred to the patched plate with a circular hole. The out-of-plane deformation causes stress increase of the patched plate with a circular hole. Therefore, we investigate that the out-of-plane deformation affects relaxation of the stress concentration in the plate with a circular hole on this relaxation method. As a result, it was confirmed that the out-of-plane deformation inhibits relaxation of the stress concentration on the plate with a circular hole.

Keywords: stress concentration, patch, out-of-plane deformation, Finite Element Analysis

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Authors: Janmejoy Gupta, Arnab Paul, Manjari Chakraborty

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Jharkhand is a state located in the eastern part of India. The Tropic of Cancer (23.5 degree North latitude line) passes through Ranchi district in Jharkhand. Mud huts with burnt clay tiled roofs in Jharkhand are an integral component of the state’s vernacular architecture. They come in various shapes, with a number of them having a courtyard type of plan. In general, it has been stated that designing dwellings with courtyards in them is a climate-responsive strategy in composite climate. The truth behind this hypothesis is investigated in this paper. In this paper, three types of mud huts with courtyards situated in Ranchi district in Jharkhand are taken as a study and through temperature measurements in the south-side rooms and courtyards, in addition to Autodesk Ecotect (Version 2011) software simulations, their thermal performance throughout the year are observed. Temperature measurements are specifically taken during the peak of summer and winter and the average temperatures in the rooms and courtyards during seven day-periods in peak of summer and peak of winter are plotted graphically. Thereafter, on the basis of the study and software simulations, the hypothesis is verified and the thermally better performing dwelling types in summer and winter identified among the three sub-types studied. Certain recommendations with respect to increasing thermal comfort in courtyard type mud huts in general are also made. It is found that all courtyard type dwellings do not necessarily show better thermal performance in summer and winter in composite climate. The U shaped dwelling with open courtyard on southern side offers maximum amount of thermal-comfort inside the rooms in the hotter part of the year and the square hut with a central courtyard, with the courtyard being closed from all sides, shows superior thermal performance in winter. The courtyards in all the three case-studies are found to get excessively heated up during summer.

Keywords: courtyard, mud huts, simulations, temperature measurements, thermal performance

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Authors: Amit Kumar Haldar, Mark Simms, Ian McDevitt, Anthony Comer

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Interface properties of fiber metal laminates (FML) affects the integrity and deformation failure modes. In this paper, the mechanical behaviours of Ti/GFRP/Ti laminates were experimentally investigated through low-velocity impact tests. Two different surface treatments of Titanium (Ti-6Al-4V) alloy sheets were prepared to obtain the composite interface properties based on annealing and sandblast surface treatment processes. The deformation failure modes, impact load sustaining ability and energy absorption capacity of FMLs were analysed. The impact load and modulus were shown to be dependent on the surface treatments of Titanium (Ti-6Al-4V) alloy sheets. It was demonstrated that the impact load performance was enhanced when titanium surfaces were annealed and sandblasted. It has also been shown that the values of the strength and energy absorption were slightly higher when the tests conducted at relatively higher loading rate, as a result of the rate-sensitive effects on the damage resistance of the FML.

Keywords: fiber metal laminates, metal composite interface, indentation, low velocity impact

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Authors: R. S. Yadav, J. Havlica, I. Kuřitka, Z. Kozakova, J. Masilko, M. Hajdúchová, V. Enev, J. Wasserbauer

Abstract:

In this present work, CoFe2-xNdxO4 (0.0 ≤ x ≥0.1) spinel ferrite nanoparticles were synthesized by starch-assisted sol-gel auto-combustion method. Powder X-ray diffraction patterns were revealed the formation of cubic spinel ferrite with the signature of NdFeO3 phase at higher Nd3+ concentration. The field emission scanning electron microscopy study demonstrated the spherical nanoparticle in the size range between 5-15 nm. Raman and Fourier Transform Infrared spectra supported the formation of the spinel ferrite structure in the nanocrystalline form. The X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of Co2+ and Fe3+ at octahedral as well as a tetrahedral site in CoFe2-xNdxO4 nanoparticles. The change in magnetic properties with a variation of concentration of Nd3+ ions in cobalt ferrite nanoparticles was observed.

Keywords: nanoparticles, spinel ferrites, sol-gel auto-combustion method, CoFe2-xNdxO4

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Authors: Steven Ploetz, Andreas Lohmueller, Robert F. Singer

Abstract:

The outstanding performance of aluminum matrix composites (AMCs) regarding stiffness/weight ratio makes AMCs attractive material for lightweight construction. Low-density boride compounds promise simultaneously an increase in stiffness and decrease in composite density. This is why boron carbide is chosen for composite manufacturing. The composites are fabricated with the stir casting process. To avoid gas entrapment during mixing and ensure nonporous composites, partial vacuum is adapted during particle feeding and stirring. Poor wettability of boron carbide with liquid aluminum hinders particle incorporation, but alloying elements such as magnesium and titanium could improve wettability and thus particle incorporation. Next to alloying elements, adapted stirring parameters and impeller geometries improve particle incorporation and enable homogenous particle distribution and high particle volume fractions of boron carbide. AMCs with up to 15 vol.% of boron carbide particles are produced via melt stirring, resulting in an increase in stiffness and strength.

Keywords: aluminum matrix composites, boron carbide, stiffness, stir casting

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Authors: Saji Varghese

Abstract:

Naturally dried and fallen coconut leaves and found in abundance in India and other coconut growing regions of the world. These fallen coconut leaves are usually burnt by farmers in landfills and open kitchens, leading to CO2 and particulate emissions. The innovation of biodegradable drinking straws from naturally dried and fallen coconut leaves by this researcher and his team has opened up opportunities to create value out of this agri-waste leading to i. prevention of burning of these discarded leaves ii. income generating opportunities to women in rural areas of coconut growing regions iii. an alternative to single use plastic straws. The team has developed five special purpose machines, which are deployed in the three villages on a pilot basis where 36 women are employed. The women are trained in the use of these machines, and the straws which are in good demand are sold globally. The present paper analyses the prospective impact of this innovation on the incomes of women working at the straw production centres and the consequent impact on their standards of living, The paper also analyses the impact of this innovation in the reduction of CO2 and particulate emissions and makes a case for support from Govt and Non Govt organizations in coconut growing regions to set up straw production centres to boost rural circular economy and to reduce carbon footprint and eliminate plastic pollution

Keywords: drinking straws, coconut leaves, circular economy, sustainability

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Authors: Gizem Arslan Özgen, Kutay Yücetürk, Metin Tanoğlu, Engin Aktaş

Abstract:

Power transmitted from the engine to the final drive where useful work is applied through a system consisting of a gearbox, clutch, drive shaft and a differential in the rear-wheel-drive automobiles. It is well-known that the steel drive shaft is usually manufactured in two pieces to increase the fundamental bending natural frequency to ensure safe operation conditions. In this work, hybrid one-piece propeller shafts composed of carbon/epoxy and glass/epoxy composites have been designed for a rear wheel drive automobile satisfying three design specifications, such as static torque transmission capability, torsional buckling and the fundamental natural bending frequency. Hybridization of carbon and glass fibers is being studied to optimize the cost/performance requirements. Composites shaft materials with various fiber orientation angles and stacking sequences are being fabricated and analyzed using finite element analysis (FEA).

Keywords: composite propeller shaft, hybridization, epoxy matrix, static torque transmission capability, torsional buckling strength, fundamental natural bending frequency.

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Authors: Iacopo Testi, Diego Pajarito, Nicoletta Roberto, Carmen Greco

Abstract:

Today, a consistent segment of the world’s population lives in urban areas, and this proportion will vastly increase in the next decades. Therefore, understanding the key trends in urbanization, likely to unfold over the coming years, is crucial to the implementation of sustainable urban strategies. In parallel, the daily amount of digital data produced will be expanding at an exponential rate during the following years. The analysis of various types of data sets and its derived applications have incredible potential across different crucial sectors such as healthcare, housing, transportation, energy, and education. Nevertheless, in city development, architects and urban planners appear to rely mostly on traditional and analogical techniques of data collection. This paper investigates the prospective of the data science field, appearing to be a formidable resource to assist city managers in identifying strategies to enhance the social, economic, and environmental sustainability of our urban areas. The collection of different new layers of information would definitely enhance planners' capabilities to comprehend more in-depth urban phenomena such as gentrification, land use definition, mobility, or critical infrastructural issues. Specifically, the research results correlate economic, commercial, demographic, and housing data with the purpose of defining the youth economic discomfort index. The statistical composite index provides insights regarding the economic disadvantage of citizens aged between 18 years and 29 years, and results clearly display that central urban zones and more disadvantaged than peripheral ones. The experimental set up selected the city of Rome as the testing ground of the whole investigation. The methodology aims at applying statistical and spatial analysis to construct a composite index supporting informed data-driven decisions for urban planning.

Keywords: data science, spatial analysis, composite index, Rome, urban planning, youth economic discomfort index

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Authors: Shingo Murakami, Shinichi Enoki

Abstract:

In structures, stress concentration is a factor of fatigue fracture. Basically, the stress concentration is a phenomenon that should be avoided. However, it is difficult to avoid the stress concentration. Therefore, relaxation of the stress concentration is important. The stress concentration arises from notches and circular holes. There is a relaxation method that a composite patch covers a notch and a circular hole. This relaxation method is used to repair aerial wings, but it is not systematized. Composites are more expensive than single materials. Accordingly, we propose the relaxation method that a single material patch covers a notch and a circular hole, and aim to systematize this relaxation method. We performed FEA (Finite Element Analysis) about an object by using a three-dimensional FEA model. The object was that a patch adheres to a plate with a circular hole. And, a uniaxial tensile load acts on the patched plate with a circular hole. In the three-dimensional FEA model, it is not easy to model the adhesion layer. Basically, the yield stress of the adhesive is smaller than that of adherents. Accordingly, the adhesion layer gets to plastic deformation earlier than the adherents under the yield load of adherents. Therefore, we propose the three-dimensional FEA model which is applied a nonlinear elastic region to the adhesion layer. The nonlinear elastic region was calculated by a bilinear approximation. We compared the analysis results with the tensile test results to confirm whether the analysis model has usefulness. As a result, the analysis results agreed with the tensile test results. And, we confirmed that the analysis model has usefulness. As a result that the three-dimensional FEA model was used to the analysis, it was confirmed that an out-of-plane deformation occurred to the patched plate with a circular hole. The out-of-plane deformation causes stress increase of the patched plate with a circular hole. Therefore, we investigated that the out-of-plane deformation affects relaxation of the stress concentration in the plate with a circular hole on this relaxation method. As a result, it was confirmed that the out-of-plane deformation inhibits relaxation of the stress concentration on the plate with a circular hole.

Keywords: stress concentration, patch, out-of-plane deformation, Finite Element Analysis

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Authors: Woo Young Jung, Sung Min Park, Ho Young Son, Viriyavudh Sim

Abstract:

This study presents a way to reduce earthquake damage and emergency rehabilitation of critical structures such as schools, high-tech factories, and hospitals due to strong ground motions associated with climate changes. Regarding recent trend, a strong earthquake causes serious damage to critical structures and then the critical structure might be influenced by sequence aftershocks (or tsunami) due to fault plane adjustments. Therefore, in order to improve seismic performance of critical structures, retrofitted or strengthening study of the structures under aftershocks sequence after emergency rehabilitation of the structures subjected to strong earthquakes is widely carried out. Consequently, this study used composite material for emergency rehabilitation of the structure rather than concrete and steel materials because of high strength and stiffness, lightweight, rapid manufacturing, and dynamic performance. Also, this study was to develop or improve the seismic performance or seismic retrofit of critical structures subjected to strong ground motions and earthquake aftershocks, by utilizing GFRP-Corrugated Infill Panels (GCIP).

Keywords: aftershock, composite material, GFRP, infill panel

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Authors: Christopher Okechukwu Ndukwe

Abstract:

This paper investigates and categorizes the flexural damage mechanisms in composite materials caused by mesoscopic out-of-plane buckle defects that occur during the initial stage of the resin transfer molding (RTM) process. The findings of this study have significant practical implications for the manufacturing and use of composite materials, as they provide a deeper understanding of these damage mechanisms and their analysis. During the initial stage of shaping a preform, alterations, and distortions in the reinforcement sample can significantly lead to defects, such as buckling, especially when forming double-curvature geometries. These recurring mesoscopic defects have been investigated using a specialized laboratory bench designed to reproduce buckle defects like those found in complex geometric shapes, such as tetrahedrons. The study examined two sample configurations with buckle defects in the longitudinal and transverse directions alongside a reference sample for comparison. An acoustic emission (AE) system, a well-regarded non-contact method for monitoring structural health, was used to analyze the mechanical behavior of material samples in detail. An unsupervised K-means algorithm was employed to classify the damage mechanisms—such as matrix cracking, interface damage, and fiber breakage linked to the samples' failure. A standard was established based on three AE parameters: absolute energy, amplitude, and the number of AE events. This standard helped identify the origin and sequence of damage propagation. Initially, the results of the AE parameters were superimposed with the flexural loading curves to pinpoint the loading phases during which damage began and the specific points at which the samples ultimately failed. The normalized density of AE events related to different damage mechanisms was evaluated by analyzing the number of AE events within the amplitude domain of the AE signals. The ranges of the identified damage mechanisms in the amplitude plane illustrate the progression and order of load transfer among the elements of the composite material. In the reference sample, the AE event signals corresponding to the three classes of damage mechanisms partially overlap with adjacent signals. In contrast, the two defective sample configurations showed that the overlapping AE event signals for the respective damage mechanisms converged within the intermediate damage mode area at specific points, depending on the sample configuration. The convergence points in the samples with transverse defects were identified relatively earlier than in the other samples. Low and high amplitude ranges characterize the matrix cracking and fiber breakage damage mechanisms. The low amplitude damage occurred over a more extended length, while the high amplitude damage began much earlier. This results in the signals from both damage mechanisms converging at the center of the interface damage zone. This convergence suggests that all individual composite components fail concurrently at specific points in the defective samples, resulting in rapid fragmentation and ultimately contributing to failure. Overall, the results show that mesoscopic out-of-plane buckling in all directions affects the composite's flexural response, with more severe effects observed when the load is applied transversely.

Keywords: acoustic emission, composite reinforcement, damage mechanisms, mesoscopic buckle defects

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