Search results for: fibre reinforced laminates

Authors: Herman Ruswan Suwarman, Ahmad Rivai, Mochamad Saidiman, Kuncoro Diharjo, Dody Ariawan

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The use of biodegradable composite to solve ecological and environmental problems has currently risen as a trend. With the increasing use of biodegradable composite comes an increasing need to fabricate it properly. Yet this understanding has remained a challenge for the design engineer. Therefore, this study aims to explore how to combine coconut coir as a reinforcing material and polypropylene (PP) as a biodegradable polymer matrix. By using Hotpress Molding, two methods were developed and compared. The difference between these two methods is not only the step of fabrication but also the raw material. The first method involved a PP sheet and the second used PP pellets directly. Based on the results, it can be concluded that PP pellets yield better results, where the composite was produced in a shorter time, with an evenly distributed coconut coir and a smaller number of voids.

Keywords: biodegradable, coconut coir, hot press molding, polypropylene

Procedia PDF Downloads 146

Authors: Houssem Ayari

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Sheet molding compounds (SMC) are high strength thermoset moulding materials reinforced with glass treated with thermocompression. SMC composites combine fibreglass resins and polyester/phenolic/vinyl and unsaturated acrylic to produce a high strength moulding compound. These materials are usually formulated to meet the performance requirements of the moulding part. In addition, the vinyl ester resins used in the new advanced SMC systems (A-SMC) have many desirable features, including mechanical properties comparable to epoxy, excellent chemical resistance and tensile resistance, and cost competitiveness. In this paper, a proposed model is used to take into account the Young modulus evolutions of advanced SMC systems (A-SMC) composite under fatigue tests. The proposed model and the used approach are in good agreement with the experimental results.

Keywords: composites SFRC, damage, fatigue, Mori-Tanaka

Procedia PDF Downloads 117

Authors: Iyabode A. Kehinde, Temitope A. Oyedele, Clement G. Afolabi

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One of the limitations of African yam bean (AYB) (Sphenostylis sternocarpa) is poor storage ability due to the adverse effect of seed-borne fungi. This study was conducted to examine the effects of storage methods on the nutritive composition of AYB seeds stored in three types of storage materials viz; Jute bags, Polypropylene bags, and Plastic Bowls. Freshly harvested seeds of AYB seeds were stored in all the storage materials for 6 months using 2 × 3 factorial (2 AYB cultivars and 3 storage methods) in 3 replicates. The proximate analysis of the stored AYB seeds was carried out at 3 and 6 months after storage using standard methods. The temperature and relative humidity of the storeroom was recorded monthly with Kestrel pocket weather tracker 4000. Seeds stored in jute bags gave the best values for crude protein (24.87%), ash (5.69%) and fat content (6.64%) but recorded least values for crude fibre (2.55%), carbohydrate (50.86%) and moisture content (12.68%) at the 6th month of storage. The temperature of the storeroom decreased from 32.9ºC - 28.3ºC, while the relative humidity increased from 78% - 86%. Decreased incidence of field fungi namely: Rhizopus oryzae, Aspergillus flavus, Geotricum candidum, Aspergillus fumigatus and Mucor meihei was accompanied by the increase in storage fungi viz: Apergillus niger, Mucor hiemalis, Penicillium espansum and Penicillium atrovenetum with prolonged storage. The study showed that of the three storage materials jute bag was more effective at preserving AYB seeds.

Keywords: storage methods, proximate composition, African Yam Bean, fungi

Procedia PDF Downloads 134

Authors: A. C. Vidal, D. R. Mulinari, C. F. Bandeira, S. R. Montoro

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Due to the great effort suffered by foot during movement, is of great importance to count on a shoe that has a proper structure and excellent support tread to prevent the immediate and long-term consequences in all parts of the body. In this sense, new reinforcements of insoles with high impact absorption were developed in this work, from a polyurethane (PU) biocomposite derived from castor oil reinforced or not with palm fibers. These insoles have been obtained from the mixture with polyol prepolymer (diisocyanate) and subsequently were evaluated morphologically, mechanically and by thermal analysis. The results revealed that the biocomposites showed lower flexural strength, higher impact strength and open interconnected pores in their microstructure, but with smaller cells and degradation temperature slightly higher compared to the marketed material, showing interesting properties for a possible application as reinforcement of insoles.

Keywords: composite, polyurethane insole, palm fibers, plantar insoles reinforcement

Procedia PDF Downloads 417

Authors: Marco A. S. González, Marlova P. Kulakowski, Luciano G. Breitenbach, Felipe Kirch

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The AEC sector has an expressive environmental responsibility. Actually, most building materials have severe environmental impacts along their production cycle. Professionals enrolled in building design may choice the materials and techniques with less impact among the viable options. This work presents a study about embodied energy in materials of two typical Brazilian constructive alternatives. The construction options considered are reinforced concrete structure and structural masonry. The study was developed for the region of São Leopoldo, southern Brazil. Results indicated that the energy embodied in these two constructive systems is approximately 1.72 GJ•m-2 and 1.26 GJ•m-2, respectively. It may be concluded that the embodied energy is lower in the structural masonry system, with a reduction around to 1/4 in relation to the traditional option. The results can be used to help design decisions.

Keywords: civil construction, sustainability, embodied energy, Brazil

Procedia PDF Downloads 437

Authors: Stephen O. Amiandamhen, Martina Meinken, Luvuyo Tyhoda

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The properties of Hemp (Cannabis sativa) in phosphate bonded composites were investigated in this research. Hemp hurds were collected from the Hemporium institute for research, South Africa. The hurds were air-dried and shredded using a hammer mill. The shives were screened into different particle sizes and were treated separately with 5% solution of acetic anhydride and sodium hydroxide. The binding matrix was prepared using a reactive magnesia, phosphoric acid, class S fly ash and unslaked lime. The treated and untreated hemp fibers were mixed thoroughly in different ratios with the inorganic matrix. Boric acid and excess water were used to retard and control the rate of the reaction and the setting of the binder. The Hemp composite was formed in a rectangular mold and compressed at room temperature at a pressure of 100KPa. After de-molding the composites, they were cured in a conditioning room for 96 h. Physical and mechanical tests were conducted to evaluate the properties of the composites. A central composite design (CCD) was used to determine the best conditions to optimize the performance of the composites. Thereafter, these combinations were applied in the production of the composites, and the properties were evaluated. Scanning electron microscopy (SEM) was used to carry out the advance examination of the behavior of the composites while X-ray diffractometry (XRD) was used to analyze the reaction pathway in the composites. The results revealed that all properties of phosphate bonded Hemp composites exceeded the LD-1 grade classification of particle boards. The proposed product can be used for ceiling, partitioning, wall claddings and underlayment.

Keywords: CCD, fly ash, magnesia, phosphate bonded hemp composites, phosphoric acid, unslaked lime

Procedia PDF Downloads 435

Authors: Davide Cocchi, Andrea Zucchelli, Luca Raimondi, Maria Brugo Tommaso

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The increasing attention is given to the issues of environmental pollution and climate change is exponentially stimulating the development of electrically propelled vehicles powered by renewable energy, in particular, the solar one. Given the small amount of solar energy that can be stored and subsequently transformed into propulsive energy, it is necessary to develop vehicles with high mechanical, electrical and aerodynamic efficiencies along with reduced masses. The reduction of the masses is of fundamental relevance especially for the unsprung masses, that is the assembly of those elements that do not undergo a variation of their distance from the ground (wheel, suspension system, hub, upright, braking system). Therefore, the reduction of unsprung masses is fundamental in decreasing the rolling inertia and improving the drivability, comfort, and performance of the vehicle. This principle applies even more in solar propelled vehicles, equipped with an electric motor that is connected directly to the wheel hub. In this solution, the electric motor is integrated inside the wheel. Since the electric motor is part of the unsprung masses, the development of compact and lightweight solutions is of fundamental importance. The purpose of this research is the design development and optimization of a CFRP 16 wheel hub motor for solar propulsion vehicles that can carry up to four people. In addition to trying to maximize aspects of primary importance such as mass, strength, and stiffness, other innovative constructive aspects were explored. One of the main objectives has been to achieve a high geometric packing in order to ensure a reduced lateral dimension, without reducing the power exerted by the electric motor. In the final solution, it was possible to realize a wheel hub motor assembly completely comprised inside the rim width, for a total lateral overall dimension of less than 100 mm. This result was achieved by developing an innovative connection system between the wheel and the rotor with a double purpose: centering and transmission of the driving torque. This solution with appropriate interlocking noses allows the transfer of high torques and at the same time guarantees both the centering and the necessary stiffness of the transmission system. Moreover, to avoid delamination in critical areas, evaluated by means of FEM analysis using 3D Hashin damage criteria, electrospun nanofibrous mats have been interleaved between CFRP critical layers. In order to reduce rolling resistance, the rim has been designed to withstand high inflation pressure. Laboratory tests have been performed on the rim using the Digital Image Correlation technique (DIC). The wheel has been tested for fatigue bending according to E/ECE/324 R124e.

Keywords: composite laminate, delamination, DIC, lightweight vehicle, motor hub wheel, nanofiber

Procedia PDF Downloads 214

Authors: Kaddour Ziani, Méghit Boumédiène Khaled

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Forty Hamra single non-castrated male lambs were included in the present study. Traits analyzed were weighted at birth (BW) every 20 days. At 99.15±1.07 days old, the animals were weaned, then divided in two identical groups: control and experimental lambs (n=20) according to their live weight; 24.63±0.47 and 24.35±0.64 Kg respectively. During 59 days, two varieties of feed were given to assess the growth performance. The feeding system consisted of supplying a commercial concentrate (corn based) for control lambs. However, a similar amount of experimental concentrate (barley based) was given to the experimental ones. Both diets were supplemented with 200g straw of barley/animal/ration. 10 lambs fed with experimental concentrate were slaughtered at 37.85±0.78 Kg live weight. The growth performance, the diet cost, and some of the carcass and meat characteristics were evaluated. Chemical analysis of both given diets showed an elevated crude fibre content in the commercial concentrate. However, the experimental concentrate contained higher amounts of calcium. Both groups grew at a similar rate (p > 0.05) and showed the same final body weight. Concerning the cost of the given diet, a significant difference has been found (p ≤ 0.001), between both diets. This could affect the price of the produced meat. The dressing percentage was 46.65%, with 2.49% of carcass shrink. Furthermore, an interesting percentage of total muscle was obtained (63.73%) with a good carcass conformation scoring 9.56. Compared to other breed sheep, “Hamra” carcass could be considered as the most valuable economically.

Keywords: Carcass characteristics, feeding cost, growth performance, Hamra lamb, meat

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Authors: Abhishek Mangal, Kunal Tongaria, S. Mandal, Devendra Mohan

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Carbonation of reinforced concrete structures has emerged as one of the major challenges for Civil engineers across the world. With increasing emissions from various activities, carbon dioxide concentration in the atmosphere has been eve rising, enhancing its penetration in porous concrete, reaching steel bars and ultimately leading to premature failure. Several literatures have been published dealing with the various interdependent variables related to carbonation. However, with innumerable variability a generalization of these data proves to be a troublesome task. This paper looks into this carbonation anomaly in concrete structures caused by various external variables such as relative humidity, concentration of CO2, curing period and ambient temperature. Significant discussions and comparisons have been presented on the basis of various studies conducted with an aim to predict the depth of carbonation as a function of these multidimensional parameters using various numerical and statistical modelling techniques.

Keywords: carbonation, curing, exposure conditions, relative humidity

Procedia PDF Downloads 253

Authors: M. Palizvan, M. T. Abadi, M. H. Sadr

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Due to variations in damage mechanisms in the microscale, the behavior of fiber-reinforced composites is nonlinear and difficult to model. To make use of computational advantages, homogenization method is applied to the micro-scale model in order to minimize the cost at the expense of detail of local microscale phenomena. In this paper, the effective stiffness is calculated using the homogenization of nonlinear behavior of a composite representative volume element (RVE) containing fiber-matrix debonding. The damage modes for the RVE are considered by using cohesive elements and contacts for the cohesive behavior of the interface between fiber and matrix. To predict more realistic responses of composite materials, different random distributions of fibers are proposed besides square and hexagonal arrays. It was shown that in some cases, there is quite different damage behavior in different fiber distributions. A comprehensive comparison has been made between different graphs.

Keywords: homogenization, cohesive zone model, fiber-matrix debonding, RVE

Procedia PDF Downloads 167

Authors: Sh. Minapoor, S. Ajeli, M. Javadi Toghchi

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Non-crimp 3D orthogonal fabric composite is one of the textile-based composite materials that are rapidly developing light-weight engineering materials. The present paper focuses on geometric and micro mechanical modeling of non-crimp 3D orthogonal carbon fabric and composites reinforced with it for aerospace applications. In this research meso-finite element (FE) modeling employs for stress analysis in different load conditions. Since mechanical testing of expensive textile carbon composites with specific application isn't affordable, simulation composite in a virtual environment is a helpful way to investigate its mechanical properties in different conditions.

Keywords: woven composite, aerospace applications, finite element method, mechanical properties

Procedia PDF Downloads 465

Authors: Z. Adnan, M. M. Habib

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The laboratory tests for measuring the effects of small strain to the shear strength and maximum stiffness development of post-cyclic degradation of hemic peat are reviewed in this paper. A series of laboratory testing has been conducted to fulfil the objective of this research to study the post-cyclic behaviour of peat soil and focuses on the small strain characteristics. For this purpose, a number of strain-controlled static, cyclic and post-cyclic triaxial tests were carried out in undrained condition on hemic peat soil. The shear strength and maximum stiffness of hemic peat are evaluated immediately after post-cyclic monotonic testing. There are two soil samples taken from West Johor and East Malaysia peat soil. Based on these laboratories and field testing data, it was found that the shear strength and maximum stiffness of peat soil decreased in post-cyclic monotonic loading than its initial shear strength and stiffness. In particular, degradation in shear strength and stiffness is more sensitive for peat soil due to fragile and uniform fibre structures. Shear strength of peat soil, τ_max = 12.53 kPa (Beaufort peat, BFpt) and 36.61 kPa (Parit Nipah peat, PNpt) decreased than its initial 58.46 kPa and 91.67 kPa. The maximum stiffness, G_max = 0.23 and 0.25 decreased markedly with post-cyclic, G_max = 0.04 and 0.09. Simple correlations between the G_max and the τ_max effects due to small strain, ε = 0.1, the G_max values for post-cyclic are relatively low compared to its initial G_max. As a consequence, the reported values and patterns of both the West Johor and East Malaysia peat soil are generally the same.

Keywords: post-cyclic, strain, maximum stiffness, shear strength

Procedia PDF Downloads 302

Authors: W. Badla

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A significant portion of the buildings constructed in Algeria is structural frames with infill panels which are usually considered as non structural components and are neglected in the analysis. However, these masonry panels tend to influence the structural response. Thus, these structures can be regarded as seismic risk buildings, although in the Algerian seismic code there is little guidance on the seismic evaluation of infilled frame buildings. In this study, three RC frames with 2, 4, and 8 story and subjected to three recorded Algerian accelerograms are studied. The diagonal strut approach is adopted for modeling the infill panels and a fiber model is used to model RC members. This paper reports on the seismic evaluation of RC frames with brick infill panels. The results obtained show that the masonry panels enhance the load lateral capacity of the buildings and the infill panel configuration influences the response of the structures.

Keywords: seismic design, RC frames, infill panels, non linear dynamic analysis

Procedia PDF Downloads 546

Authors: Sri Sai Ramya Bojedla, Falguni Pati

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Nature provides the best of solutions to humans. One such incredible gift to regenerative medicine is silk. The literature has publicized a long appreciation for silk owing to its incredible physical and biological assets. Its bioactive nature, unique mechanical strength, and processing flexibility make us curious to explore further to apply it in the clinics for the welfare of mankind. In this study, Antheraea mylitta and Bombyx mori silk fibroin microfibers are developed by two economical and straightforward steps via degumming and hydrolysis for the first time, and a bioactive composite is manufactured by mixing silk fibroin microfibers at various concentrations with polycaprolactone (PCL), a biocompatible, aliphatic semi-crystalline synthetic polymer. Reconstructive surgery in any part of the body except for the maxillofacial region deals with replacing its function. But answering both the aesthetics and function is of utmost importance when it comes to facial reconstruction as it plays a critical role in the psychological and social well-being of the patient. The main concern in developing adequate bone graft substitutes or a scaffold is the noteworthy variation in each patient's bone anatomy. Additionally, the anatomical shape and size will vary based on the type of defect. The advent of additive manufacturing (AM) or 3D printing techniques to bone tissue engineering has facilitated overcoming many of the restraints of conventional fabrication techniques. The acquired patient's CT data is converted into a stereolithographic (STL)-file which is further utilized by the 3D printer to create a 3D scaffold structure in an interconnected layer-by-layer fashion. This study aims to address the limitations of currently available materials and fabrication technologies and develop a customized biomaterial implant via 3D printing technology to reconstruct complex form, function, and aesthetics of the facial anatomy. These composite scaffolds underwent structural and mechanical characterization. Atomic force microscopic (AFM) and field emission scanning electron microscopic (FESEM) images showed the uniform dispersion of the silk fibroin microfibers in the PCL matrix. With the addition of silk, there is improvement in the compressive strength of the hybrid scaffolds. The scaffolds with Antheraea mylitta silk revealed higher compressive modulus than that of Bombyx mori silk. The above results of PCL-silk scaffolds strongly recommend their utilization in bone regenerative applications. Successful completion of this research will provide a great weapon in the maxillofacial reconstructive armamentarium.

Keywords: compressive modulus, 3d printing, maxillofacial reconstruction, natural fiber reinforced composites, silk fibroin microfibers

Procedia PDF Downloads 197

Authors: Marzieh Bakhtiary Noodeh, Mahla Zabet

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Attempts have been carried out to enhance the anticorrosion properties as well as edge coverage of an automotive electrocoating using the nano silica particles. To this end, the automotive electrocoating was reinforced with the nano silica particles at various weight fractions. The electrocoats were applied on the surface of punched edge followed by curing at 160⁰C for 20 min. The effects of nano silica particles on the rheological properties, influencing edge coverage were studied by a RMS (Rheometric Mechanical Spectrometer) technique. The anticorrosion properties were studied by a salt-spray test. The results obtained revealed that nano silica particles can significantly enhance the edge coverage by increasing minimum melt viscosity of electrocoats. It was shown that using 4 wt% nano silica particles, both anticorrosion properties and edge coverage of the electrocoats were significantly improved.

Keywords: nano silica, electrocoat, edge coverage, anticorrosion

Procedia PDF Downloads 307

Authors: Ladele Ademola A., Nkiru T. Meludu, Olufunke Ezekiel, Olaoye Taye F., Okanlowan Oluwatoyin M.

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Value addition to agricultural produce is of possible potential in reducing poverty, improving food security and malnutrition, therefore the need to develop small and micro-enterprises of sweet potato production. The study was carried out in Nigeria to determine the acceptability of blends sweet potato (Ipomea batatas) and commodities yellow maize (Zea mays), millet (Pennisetum glaucum), soybean (Glycine max), bambara groundnut (Vigna subterranean), guinea corn (Sorghum vulgare), wheat (Triticum aestivum), and roselle (Hibiscus sabdariffa) through sensory evaluation. Sweet potato (Ipomea batatas) roots were processed using two methods. The first method involved the use of a fabricated gas powered cabinet dryer to dry sulphited chips and the second method was the use of traditional sun drying method without the addition of the chemical. The blends were also assessed in terms of functional, chemical and color properties. Most acceptable blends include BAW (80:20 of sweet potato/wheat), BBC (80:20 of sweet potato/guinea corn), AAB (60:40 of sweet potato/guinea corn), YTE (100% soybean), TYG (100% sweet potato), KTN (100% wheat flour), XGP (80:20 of sweet potato/soybean), XAX (60:40 of sweet potato/wheat), LSS (100% Roselle), CHK (100% Guinea corn), and ABC (60:40% of sweet potato/ yellow maize). In addition, chemical analysis carried out revealed that sweet potato has high percentage of vitamins A and C, potassium (K), manganese (Mn), calcium (Ca), magnesium (Mg) and iron (Fe) and fibre content. There is also an increase of vitamin A and Iron in the blended products.

Keywords: blends, diversification, sensory evaluation, sweet potato, utilization

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Authors: Magdi M. E. Zumrawi, Nehla Mansour

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This paper aims to assess the efficiency of using geogrid reinforcement for subgrade stabilization. The literature of applying geogrid reinforcement technique for pavements built on soft subgrades and the previous experiences were reviewed. Laboratory tests were conducted on soil reinforced with geogrids in one or several layers. The soil specimens were compacted in four layers with or without geogrid sheets. The California Bearing Ratio (CBR) test, in soaking condition, was performed on natural soil and soil-geogrid specimens. The test results revealed that the CBR value is much affected by the geogrid sheet location and the number of sheets used in the soil specimen. When a geogrid sheet was placed at the 1^st layer of the soil, there was an increment of 26% in the CBR value. Moreover, the CBR value was significantly increased by 62% when geogrid sheets were placed at all four layers. The high CBR value is attributed to interface friction and interlock involved in the geogrid/ soil interactions. It could be concluded that geogrid reinforcement is successful and more economical technique.

Keywords: geogrid, reinforcement, stabilization, subgrade

Procedia PDF Downloads 320

Authors: Menonjyoti Kalita, Pradip Baishya

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In recent times, the world has been facing serious environmental concerns and issues, such as sustainability and cost, due to the overproduction of synthetic materials and their participation in degrading the environment by means of industrial waste and non-biodegradable characteristics. As such, biocomposites come in handy to ease such troubles. Bio-based composites are promising materials for future applications for substituting synthetic packaging materials. The challenge of making packaging materials lighter, safer and cheaper leads to investigating advanced materials with desired properties. Also, awareness of environmental issues forces researchers and manufacturers to spend effort on composite and bio-composite materials fields. This paper explores and tests some nature-friendly materials has been done which can replace low-density plastics. The materials selected included sugarcane bagasse, areca palm, and bamboo leaves. Sugarcane bagasse bamboo leaves and areca palm sheath are the primary material or natural fibre for testing. These products were processed, and the tensile strength of the processed parts was tested in Micro UTM; it was found that areca palm can be used as a good building material in replacement to polypropylene and even could be used in the production of furniture with the help of epoxy resin. And for bamboo leaves, it was found that bamboo and cotton, when blended in a 50:50 ratio, it has great tensile strength. For areca, it was found that areca fibres can be a good substitute for polypropylene, which can be used in building construction as binding material and also other products.

Keywords: biodegradable characteristics, bio-composites, areca palm sheath, polypropylene, micro UTM

Procedia PDF Downloads 90

Authors: P. P. Woyciechowski

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Calculation of the carbon footprint of cement concrete is a complex process including consideration of the phase of primary life (components and concrete production processes, transportation, construction works, maintenance of concrete structures) and secondary life, including demolition and recycling. Taking into consideration the effect of concrete carbonation can lead to a reduction in the calculated carbon footprint of concrete. In this paper, an example of CO₂ balance for small bridge elements made of Portland cement reinforced concrete was done. The results include the effect of carbonation of concrete in a structure and of concrete rubble after demolition. It was shown that important impact of carbonation on the balance is possible only when rubble carbonation is possible. It was related to the fact that only the sequestration potential in the secondary phase of concrete life has significant value.

Keywords: carbon footprint, balance of carbon dioxide in nature, concrete carbonation, the sequestration potential of concrete

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Authors: Shahriar Shahbazpanahi, Alaleh Kamgar

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So far, the conventional experimental and theoretical analysis in fracture mechanics have been applied to study concrete flexural- cracked beams, which are strengthened using fiber reinforced polymer (FRP) composite sheets. However, there is still little knowledge about the shear capacity of a side face FRP- strengthened shear-cracked beam. A numerical analysis is herein presented to model the fracture mechanics of a four-point RC beam, with two inclined initial notch on the supports, which is strengthened with side face FRP sheets. In the present study, the shear crack is forced to conduct by using an initial notch in supports. The ABAQUS software is used to model crack propagation by conventional cohesive elements. It is observed that the FRP sheets play important roles in preventing the propagation of shear cracks.

Keywords: crack, FRP, shear, strengthening

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Authors: Adinew Gebremeskel Tizazu

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The effect of soil-structure interaction on the dynamic response of reinforced concrete buildings of regular and symmetrical geometry are considered in this study. The structures are presumed to be generally embedded in a homogenous soil formation underlain by very stiff material or bedrock. The structure-foundation–soil system is excited at the base by an earthquake ground motion. The superstructure is idealized as a system with lumped masses concentrated at the floor levels, and coupled with the substructure. The substructure system, which comprises of the foundation and soil, is represented, and replaced by springs and dashpots. Frequency-dependent impedances of the foundation system are incorporated in the discrete model in terms of the springs and dashpots coefficients. The excitation applied to the model is field ground motions of actual earthquake records. Modal superposition principle is employed to transform the equations of motion in geometrical coordinates to modal coordinates. However, the modal equations remain coupled with respect to damping terms due to the difference in damping mechanisms of the superstructure and the soil. Hence, proportional damping for the coupled structural system may not be assumed. An iterative approach is adopted and programmed to solve the system of coupled equations of motion in modal coordinates to obtain the displacement responses of the system. Parametric studies for responses of building structures with regular and symmetric plans of different structural properties and heights are made for fixed and flexible base conditions, for different soil conditions encountered in Addis Ababa. The displacement, base shear and base overturning moments are used in the comparison of different types of structures for various foundation embedment depths, site conditions and height of structures. These values are compared against those of fixed base structure. The study shows that the flexible base structures, generally exhibit different responses from those structures with fixed base. Basically, the natural circular frequencies, the base shears and the inter-story displacements for the flexible base are less than those of the fixed base structures. This trend is particularly evident when the flexible soil has large thickness. In contrast, the trend becomes less predictable, when the thickness of the flexible soil decreases. Moreover, in the latter case, the iteration undulates significantly making the prediction difficult. This is attributed to the highly jagged nature of the impedance functions of frequencies for such formations. In this case, it is difficult to conclude whether the conventional fixed-base approach yields conservative design forces, as is the case for soil formations of large thickness.

Keywords: effect of soil structure, dynamic response corroborated, the modal superposition principle, parametric studies

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Authors: Su Sin Chong, Abdul Aziz Abdul Raman, Sulaiman Wadi Harun, Hamzah Arof

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Chemical Oxygen Demand (COD) plays a vital role determination of an appropriate strategy for wastewater treatment including the control of the quality of an effluent. In this study, a new sensing method was introduced for the first time and developed to investigate chemical oxygen demand (COD) using a Mach-Zehner Interferometer (MZI)-based dye sensor. The sensor is constructed by bridging two single mode fibres (SMF1 and SMF2) with a short section (~20 mm) of multimode fibre (MMF) and was formed by tapering the MMF to generate evanescent field which is sensitive to perturbation of sensing medium. When the COD concentration increase takes effect will induce changes in output intensity and effective refractive index between the microfiber and the sensing medium. The adequacy of decisions based on COD values relies on the quality of the measurements. Therefore, the dual output response can be applied to the analytical procedure enhance measurement quality. This work presents a detailed assessment of the determination of COD values in synthetic wastewaters. Detailed models of the measurement performance, including sensitivity, reversibility, stability, and uncertainty were successfully validated by proficiency tests where supported on sound and objective criteria. Comparison of the standard method with the new proposed method was also conducted. This proposed sensor is compact, reliable and feasible to investigate the COD value.

Keywords: chemical oxygen demand, environmental sensing, Mach-Zehnder interferometer sensor, online monitoring

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Authors: Jayaraman Muniyappan, Bachchan Kr Mishra, Gautam Salkar, Swetha Manian Sridhar

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Vacuum Assisted Resin Transfer Molding (VARTM), a cost effective method of Liquid Composite Molding (LCM), is a single step process where the resin, at atmospheric pressure, is infused through a preform that is maintained under vacuum. This hydrodynamic pressure gradient is responsible for the flow of resin through the dry fabric preform. The current study has a slight variation to traditional VARTM, wherein, the resin infuses through the fabric placed on a heated mold to reduce its viscosity. The saturated preform is subjected to a cure cycle where the resin hardens as it undergoes curing. During this cycle, an uneven temperature distribution through the thickness of the composite and excess exothermic heat released due to different cure rates result in non-uniform curing. Additionally, there is a difference in thermal expansion coefficient between fiber and resin in a given plane and between adjacent plies. All these effects coupled with orthotropic coefficient of thermal expansion of the composite give rise to process-induced stresses in the laminate. Such stresses lead to part deformation when the laminate tries to relieve them as the part is released off the mold. The current study looks at simulating resin infusion, cure kinetics and the structural response of composite laminate subject to process-induced stresses.

Keywords: cure kinetics, process-induced stresses, thermal expansion coefficient, vacuum assisted resin transfer molding

Procedia PDF Downloads 240

Authors: Devendra Kumar Pandey, Debabrata Chakraborty

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The advancement in various concrete ingredients like plasticizers, additives and fibers, etc. has enabled concrete technologists to develop many viable varieties of special concretes in recent decades. Such various varieties of concrete have significant enhancement in green as well as hardened properties of concrete. A prudent selection of appropriate type of concrete can resolve many design and application issues in construction projects. This paper focuses on usage of self-compacting concrete, high early strength concrete, structural lightweight concrete, fiber reinforced concrete, high performance concrete and ultra-high strength concrete in the structures. The modified properties of strength at various ages, flowability, porosity, equilibrium density, flexural strength, elasticity, permeability etc. need to be carefully studied and incorporated into the design of the structures. The paper demonstrates various mixture combinations and the concrete properties that can be leveraged. The selection of such products based on the end use of structures has been proposed in order to efficiently utilize the modified characteristics of these concrete varieties. The study involves mapping the characteristics with benefits and savings for the structure from design perspective. Self-compacting concrete in the structure is characterized by high shuttering loads, better finish, and feasibility of closer reinforcement spacing. The structural design procedures can be modified to specify higher formwork strength, height of vertical members, cover reduction and increased ductility. The transverse reinforcement can be spaced at closer intervals compared to regular structural concrete. It allows structural lightweight concrete structures to be designed for reduced dead load, increased insulation properties. Member dimensions and steel requirement can be reduced proportionate to about 25 to 35 percent reduction in the dead load due to self-weight of concrete. Steel fiber reinforced concrete can be used to design grade slabs without primary reinforcement because of 70 to 100 percent higher tensile strength. The design procedures incorporate reduction in thickness and joint spacing. High performance concrete employs increase in the life of the structures by improvement in paste characteristics and durability by incorporating supplementary cementitious materials. Often, these are also designed for slower heat generation in the initial phase of hydration. The structural designer can incorporate the slow development of strength in the design and specify 56 or 90 days strength requirement. For designing high rise building structures, creep and elasticity properties of such concrete also need to be considered. Lastly, certain structures require a performance under loading conditions much earlier than final maturity of concrete. High early strength concrete has been designed to cater to a variety of usages at various ages as early as 8 to 12 hours. Therefore, an understanding of concrete performance specifications for special concrete is a definite door towards a superior structural design approach.

Keywords: high performance concrete, special concrete, structural design, structural lightweight concrete

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Authors: Elena Chernyak

Abstract:

The status of Russian women has changed dramatically over the course of Russian history and under different leadership and economic, political, and social conditions. The perception of women, their submissive roles, and low social status cause gender conflict that affects society: demographical issues, increased numbers of divorces, alcoholism, drug abuse, and crime. Despite the fact that around the world women are becoming more independent, protected by law, and play more important roles in society, Russian women are still dependent on men financially, socially, and psychologically. This paper critically explores the experience of Russian women over the course of over a thousand year of Russian history and how the position and image of women changed in Russian Empire, Soviet and post-Soviet Russia and what role women play in contemporary Russia. This paper is a result of deep examination of historical and religious literature, mass media, internet sources, and documents. This analysis shows that throughout history, the role and image of women in society have repeatedly varied depending on ideological and social conditions. In particular, the history of Russian women may be divided into five main periods. The first was the period of paganism, when almost all areas of life were open for women and when women were almost equal in social roles with men. During the second period, starting with the beginning of the Mongol invasion in the 13th century, the position of women was diminishing due to social transformation to the patriarchal society in which women started playing subordinate role in family and society. The third period – the period from the fourteenth through the sixteenth centuries - is a period of the total seclusion of Russian women from each part of social life. The fourth, Soviet period started after the Revolution of 1917. During that time, the position of women was drastically changed due to the transformation of traditional gender roles under the Bolshevik government. Woman's role was seen as worker-mothers who had a double duty: a worker and a mother. The final period began after the collapse of the Soviet Union. The restructuring (Perestroika) and post-Restructuring periods have had contradictory consequences and tremendous impact on Russian society. The image of women as partners and equal to men, which was promoted during the Soviet regime, has been replaced with the traditional functionalist views on family and the role of women, in which men and women have different but supposedly complementary roles. Modern Russia, despite publicly stating its commitment to equal rights, during last two decades has been reverting to an older social model with its emphasis on traditional gender roles, patriarchal ideas of dominant masculinity, and adverse attitudes to women, which are further supported and reinforced by the reviving Russian Orthodox Church. As demonstrated in this review, Russian women have never possessed the same rights as men and have always been subordinate to men. During all period of Russian history, patriarchal ideology maintained and reinforced in Russian society has always subjected women to manipulation, oppression, and victimization and portrayed women as not a ‘full human being’.

Keywords: women, Russia, patriarchy, religion, Russian Orthodox Church

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Authors: Ahmed Hashim, Aseel Abdullah

Abstract:

In this work, the fracture toughness of new green composite based on bio-PMMA resin reinforced with randomly short corn natural fiber of constant weight fraction by 10% wt was investigated. The corn fiber surface was modified by mercerization treatment with two different concentrations of sodium hydroxide (3, and 5% NaOH) for 1.5 and 3 hours respectively. The effect of mercerization treatment on the fracture behavior of the green composites was analyzed by FTIR spectra. NaOH concentration of 3% for 1.5 hrs. That was used for corn fiber green composite should the highest improvement in terms of plane strain fracture toughness KIC which increased by 62 % compared to untreated fiber composite material. On the other hand, increased both concentrations of alkali solution to 5% NaOH and time of soaking to 3 hrs. reduced the values of KIC lower than the value of the unfilled material.

Keywords: green composites, fracture toughness, corn natural fiber, bio-PMMA

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Authors: Anjan Sil, Rajni Sharma, Subrata Ray

Abstract:

The effect of carbon nanofibers (CNFs) on the electrical properties of Poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP)) based gel polymer electrolytes has been investigated in the present work. The length and diameter ranges of CNFs used in the present work are 5-50 µm and 200-600 nm, respectively. The nanocomposite gel polymer electrolytes have been synthesized by solution casting technique with varying CNFs content in terms of weight percentage. Electrochemical impedance analysis demonstrates that the reinforcement of carbon nanofibers significantly enhances the ionic conductivity of the polymer electrolyte. The decrease of crystallinity of P(VdF-HFP) due the addition of CNFs has been confirmed by X-ray diffraction (XRD). The interaction of CNFs with various constituents of nanocomposite gel polymer electrolytes has been assessed by Fourier Transform Infrared (FTIR) spectroscopy. Moreover, CNFs added gel polymer electrolytes offer superior thermal stability as compared to that of CNFs free electrolytes as confirmed by Thermogravimetric analysis (TGA).

Keywords: polymer electrolytes, CNFs, ionic conductivity, TGA

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Authors: A. Chiker, A. Benamor, A. Haddad, Y. Hadji, M. Hadji

Abstract:

Metal matrix composites (MMCs) have been of big interest for a few decades. Their major drawback lies in their enhanced mechanical performance over unreinforced alloys. They found ground in many engineering fields, such as aeronautics, aerospace, automotive, and other structural applications. One of the most used alloys as a matrix is nickel alloys, which meet the need for high-temperature mechanical properties; some attempts have been made to develop nickel base composites reinforced by high melt point and high modulus particulates. Among the carbides used as reinforcing particulates, chromium carbide is interesting for wear applications; it is widely used as a tribological coating material in high-temperature applications requiring high wear resistance and hardness. Moreover, a set of properties make it suitable for use in MMCs, such as toughness, the good corrosion and oxidation resistance of its three polymorphs -the cubic (Cr23C6), the hexagonal (Cr7C3), and the orthorhombic (Cr3C2)-, and it’s coefficient of thermal expansion that is almost equal to that of metals. The in-situ synthesis of CrC-reinforced Ni matrix composites could be achieved by the powder metallurgy route. To ensure the in-situ reactions during the sintering process, the use of phase precursors is necessary. Recently, new precursor materials have been proposed; these materials are called MAX phases. The MAX phases are thermodynamically stable nano-laminated materials displaying unusual and sometimes unique properties. These novel phases possess Mn+1AXn chemistry, where n is 1, 2, or 3, M is an early transition metal element, A is an A-group element, and X is C or N. Herein, the pressureless sintering method is used to elaborate Ni/Cr2AlC composites. Four composites were elaborated from 5, 10, 15 and 20 wt% of Cr2AlC MAX phase precursor which fully reacted with Ni-matrix at 1100 °C sintering temperature for 4 h in argon atmosphere. XRD results showed that Cr2AlC MAX phase was totally decomposed forming chromium carbide Cr7C3, and the released Al and Cr atoms diffused in Ni matrix giving rise to γ-Ni(Al,Cr) solid solution and γ’-Ni3(Al,Cr) intermetallic. Scanning Electron Microscopy (SEM) of the elaborated samples showed the presence of nanosized Cr7C3 reinforcing particles embedded in the Ni metal matrix, which have a direct impact on the tribological properties of the composites and their hardness. All the composites exhibited higher hardness than pure Ni; whereas adding 15 wt% of Cr2AlC gives the highest hardness (1.85 GPa). Using a ball-on-disc tribometer, dry sliding tests for the elaborated composites against 100Cr6 steel ball were studied under different applied loads. The microstructures and worn surface characteristics were then analyzed using SEM and Raman spectroscopy. The results show that all the composites exhibited better wear resistance compared to pure Ni, which could be explained by the formation of a lubricious tribo-layer during sliding and the good bonding between the Ni matrix and the reinforcing phases.

Keywords: composites, microscopy, sintering, wear

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Authors: Eyob Hundessa Gose

Abstract:

Nowadays, it is obviously known that the construction of different infrastructures is one measurement of the development of a country; infrastructures like buildings, bridges, roads, and railways are among them. In the capital city of Ethiopia, the so-called Addis Ababa, the Light Rail Train (LRT), was built Four years ago to satisfy the demand for transportation among the people in the city. The lane of the Train and vehicle separation Media was built with a curb and rail guard installation system to show the right-of-way and for protection of vehicles entering the Train Lane, but this Rail guard fails easily when impacted by vehicles and found that the impact load response of the Rail guard is weak and the Rail guard cannot withstand impact load. This study investigates the effect of variation of parameters such as vehicle speed and different mass effects and assesses the failure mode FRP and Steel reinforcement bar rail guards of deflection and damage state.

Keywords: impact load, fiber reinforced polymer, rail guard, LS-DYNA

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Authors: Hamid Nikzad, Shinta Yoshitomi

Abstract:

In this paper, nonlinear static pushover analysis is performed on 15 storied RC building structure with a shear wall to evaluate the seismic performance of the building. Section sizes of the members are obtained based on structural optimization method utilizing MATLAB frame optimizer, then the structure is simulated and designed in ETABS program conforming ACI 318-14 design code. The pushover curve has been generated by pushing the top node of the structure to the limited target displacement. Members failure due to the formation of plastic hinges, considering shear wall-frame structure was observed and the result of this study is presented based on current regulation of FEMA356, ASCE7-10, and ACI 318-14 design criteria

Keywords: structural optimization, linear static analysis, ETABS, MATLAB, RC moment frame, RC shear wall structures

Procedia PDF Downloads 158