Search results for: composite reinforcement

Authors: Christian C. Vaso, Rinlee Butch M. Cervera

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Solid oxide electrolysis cell (SOEC) is a promising technology for hydrogen production that will contribute to the sustainable energy of the future. An important component of this SOEC is the anode material and one of the promising anode material for such application is the Sr-doped LaMnO3 (LSM) and Yttrium-stabilized ZrO2 (YSZ) composite material. In this study, LSM/YSZ with different weight percent compositions of LSM and YSZ were synthesized using solid-state reaction method. The obtained samples, 60LSM/40YSZ, 50LSM/50YSZ, and 40LSM/60YSZ, were fully characterized for its microstructure using X-ray diffraction, FTIR, and SEM/EDS. EDS analysis confirmed the elemental composition and distribution of the synthesized samples. Surface morphology of the sample using SEM exhibited a well sintered and densified samples and revealed a beveled cube-like LSM morphology while the YSZ phase appeared to have a sphere-like microstructure. Density measurements using Archimedes principle showed relative densities greater than 90%. In addition, AC impedance measurement of the synthesized samples have been investigated at intermediate temperature range (400-700 °C) in an inert and oxygen gas flow environment. At pure states, LSM exhibited a high electronic conductivity while YSZ demonstrated an ionic conductivity of 3.25 x 10-4 S/cm at 700 °C under Oxygen gas environment with calculated activation energy of 0.85eV. The composite samples were also studied and revealed that as the YSZ content of the composite electrode increases, the total conductivity decreases.

Keywords: ceramic composites, fuel cells, strontium lanthanum manganite, yttria partially-stabilized zirconia

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Authors: A. Pattulee, I. Lawan, N. Boonnao, R. Gholami, P. Rimdusit, S. Rimdusit

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Varied types and content of ultrafine vulcanized powdered natural rubbers (UFPNR) as toughening fillers of polybenzoxazine composite are investigated in this work. Four types of UFPNR were prepared by graft polymerization of acrylonitrile monomer (AN), styrene monomer (ST), styrene-acrylonitrile copolymer (ST/AN), and styrene-methyl methacrylate copolymer (ST/MMA) onto deproteinized natural rubber (DPNR). The solid UFPNR powders with different types of grafting were finally obtained by electron beam vulcanization and a spray-drying technique. Additionally, effects of various UFPNR contents (0, 5, 10, 15, 20, and 25 wt%) on toughness of polybenzoxazine composites were studied. It was observed that the UFPNR grafted with the styrene-methyl methacrylate copolymer (UFPNR-g-(PS-co-PMMA)) exhibited the most effective toughening agent for polybenzoxazine, whereas the rubber powder content of 25 wt% was found to be the optimal filler loading in enhancing the toughness of the resulting composite. The experimental results revealed an increase of 86% in toughness and 56% in impact strength at the above UFPNR-g- (PS-co-PMMA powdered rubber content. Interestingly, the utilization of the UFPNR-g-(PS-co-PMMA as toughening agent was found to increase thermal stability (degradation temperature at 5wt.% (Td5) and glass transition temperature (Tg) of the composite i.e. an increase of 8°C and 6 °C has been observed for the Td5 and Tg, respectively.

Keywords: natural rubber, ultrafine fully vulcanized powder rubber, polybenzoxazine, polymer composite, toughening

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Authors: A. Nuchitprasittichai, N. Lerdritsirikoon, T. Khamsing

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Simulation modeling can be used to solve real world problems. It provides an understanding of a complex system. To develop a simplified model of process simulation, a suitable experimental design is required to be able to capture surface characteristics. This paper presents the experimental design and algorithm used to model the process simulation for optimization problem. The CO₂ liquefaction based on external refrigeration with two refrigeration circuits was used as a simulation case study. Latin Hypercube Sampling (LHS) was purposed to combine with existing Central Composite Design (CCD) samples to improve the performance of CCD in generating the second order model of the system. The second order model was then used as the objective function of the optimization problem. The results showed that adding LHS samples to CCD samples can help capture surface curvature characteristics. Suitable number of LHS sample points should be considered in order to get an accurate nonlinear model with minimum number of simulation experiments.

Keywords: central composite design, CO2 liquefaction, latin hypercube sampling, simulation-based optimization

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Authors: Jianzheng Wei, Duo Zhen, Zhihan Yang, Huifeng Tan

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The deployable descent technology is a lightweight entry method using an inflatable heat shield. The heatshield consists of a pressurized core which is covered by different layers of thermal insulation and flexible ablative materials in order to protect against the thermal loads. In this paper, both aluminum and silicon-aluminum aerogels were prepared by freeze-drying method. The latter material has bigger specific surface area and nano-scale pores. Mullite fibers are used as the reinforcing fibers to prepare the aerogel matrix to improve composite flexibility. The flexible composite materials were performed as an insulation layer to an underlying aramid fabric by a thermal shock test at a heat flux density of 120 kW/m² and uniaxial tensile test. These results show that the aramid fabric with untreated mullite fibers as the thermal protective layer is completely carbonized at the heat of about 60 s. The aramid fabric as a thermal resistance layer of the composite material still has good mechanical properties at the same heat condition.

Keywords: aerogel, aramid fabric, flexibility, thermal resistance

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Authors: J. Ivorra-Martinez, L. Quiles-Carrillo, J. Gomez-Caturla, T. Boronat, R. Balart

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The utilization of almond crop by-products to obtain PHBH-based composites was carried out by using an extrusion process followed by an injection to obtain test samples. To improve the properties of the resulting composite, the incorporation of OLA 8 as a coupling agent and plasticizer was additionally considered. A characterization process was carried out by the measurement of mechanical properties, thermal properties, surface morphology, and water absorption ability. The use of the almond residue allows obtaining composites based on PHBH with a higher environmental interest and lower cost.

Keywords: almond shell, PHBH, composites, compatibilization

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Authors: Mostafa Aminzadeh, Min Deng

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Modeling loss data is an important part of actuarial science. Actuaries use models to predict future losses and manage financial risk, which can be beneficial for marketing purposes. In the insurance industry, small claims happen frequently while large claims are rare. Traditional distributions such as Normal, Exponential, and inverse-Gaussian are not suitable for describing insurance data, which often show skewness and fat tails. Several authors have studied classical and Bayesian inference for parameters of composite distributions, such as Exponential-Pareto, Weibull-Pareto, and Inverse Gamma-Pareto. These models separate small to moderate losses from large losses using a threshold parameter. This research introduces a computational approach using a nonlinear regression model for loss data that relies on multiple predictors. Simulation studies were conducted to assess the accuracy of the proposed estimation method. The simulations confirmed that the proposed method provides precise estimates for regression parameters. It's important to note that this approach can be applied to datasets if goodness-of-fit tests confirm that the composite distribution under study fits the data well. To demonstrate the computations, a real data set from the insurance industry is analyzed. A Mathematica code uses the Fisher information algorithm as an iteration method to obtain the maximum likelihood estimation (MLE) of regression parameters.

Keywords: maximum likelihood estimation, fisher scoring method, non-linear regression models, composite distributions

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Authors: Anuoluwapo S. Taiwo, David S. Ayre, Morteza Khorami, Sameer S. Rahatekar

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This investigation aims to characterize the effect of Corn Cob (CC), an agricultural waste, for potential use as a filler material, reducing cement in natural fibre-reinforced cement composite boards used for building applications in low-cost housing estates in developing countries. The corn cob is readily and abundantly available in many West African States. However, this agricultural waste product has not been put to any effective use. Hence, the objective of the current research is to convert this massive agro-waste resource into a potential material for use as filler materials reducing cement contents in fibre-cement board production. Kraft pulp fibre-reinforced cement composite boards were developed with the incorporation of the corn cob powder at varying percentages of 1 – 4% as filler materials to reduce the cement content, using a laboratory-simulated vacuum de-watering process. The mechanical properties of the developed cement boards were characterized through a three-point bending test, while the fractured morphology of the cement boards was examined through a Scanning Electron Microscope (SEM). Results revealed that the flexural strength of the composite board improved significantly with an optimum enhancement of 39% when compared to the reference sample without corn cob replacement, however, the flexural behaviour (ductility) of the composite board was slightly affected by the addition of the corn cob powder at higher percentage. SEM observation of the fractured surfaces revealed good bonding at the fibre-matrix interface as well as a ductile-to-brittle fracture mechanism. Overall, the composite board incorporated with 2% corn cob powder as filler materials had the optimum properties which satisfied the minimum requirements of relevant standards for fibre cement flat sheets.

Keywords: agricultural waste, building applications, fibre-cement board, kraft pulp fibre, sustainability

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Authors: S. Alrekabi, A. Cundy, A. Lampropoulos, I. Savina

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Due to their remarkable mechanical properties, multi-wall carbon nanotubes (MWCNTs) are considered by many researchers to be a highly promising filler and reinforcement agent for enhanced performance cementitious materials. Currently, however, achieving an effective dispersion of MWCNTs remains a major challenge in developing high performance nano-cementitious composites, since carbon nanotubes tend to form large agglomerates and bundles as a consequence of Van der Waals forces. In this study, effective dispersion of low concentrations of MWCNTs at 0.01%, 0.025%, and 0.05% by weight of cement in the composite was achieved by applying different sonication conditions in combination with the use of polycarboxylate ether as a surfactant. UV-Visible spectroscopy and Transmission electron microscopy (TEM) were used to assess the dispersion of MWCNTs in water, while the dispersion states of MWCNTs within the cement composites and their surface interactions were examined by scanning electron microscopy (SEM). A high sonication intensity applied over a short time period significantly enhanced the dispersion of MWCNTs at initial mixing stages, and 0.025% of MWCNTs wt. of cement, caused 86% and 27% improvement in tensile strength and compressive strength respectively, compared with a plain cement mortar.

Keywords: dispersion, mechanical performance, multi wall carbon nanotubes, sonication conditions

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Authors: Yuan Li, Yitao Han, Zhao Zhu

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In this paper, the effect of blasting loads on steel-concrete composite bridges has been investigated considering the slope reflection effect. Reasonable values of girder size, plate thickness, stiffening rib, and other design parameters were selected according to design specifications. Modified RHT (Riedel-Hiermaier-Thoma) was used as constitutive relation in analyses. In order to simulate the slope reflection effect, the slope of the bridge was precisely built in the model. Different blasting conditions, including top, middle, and bottom explosions, were simulated. The multi-Euler domain method based on fully coupled Lagrange and Euler models was adopted for the structural analysis of the explosion process using commercial software AUTODYN. The obtained results showed that explosion overpressure was increased by 3006, 879, and 449kPa, corresponding to explosions occurring at the top, middle, and bottom of the slope, respectively. At the same time, due to energy accumulation and transmission dissipation caused by slope reflection, the corresponding yield lengths of steel beams were increased by 8, 0, and 5m, respectively.

Keywords: steel-concrete composite bridge, explosion damage, slope reflection, blasting loads, RHT

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Authors: Mazin Mohammed Sarhan Sarhan

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This paper presents an experimental study of the bond behaviour of confined concrete beams reinforced with a chequer steel plate or a deformed steel bar by using the beam-bending pullout test. A total of three beams of 225 mm width, 300 mm height, and 600 mm length were cast and tested. All the beams had the same details of compression reinforcement and stirrups; two plain steel bars of 10 mm diameter (R10) were used for the compression reinforcement, and plain steel bars (R10) at a distance of 80 mm centre to centre were used for the stirrups. The first beam was reinforced with a deformed steel bar while the remaining beams were reinforced with horizontal or vertical chequer steel plates. The results showed no significant difference in the bond force between the beams reinforced with a deformed steel bar or a horizontal steel plate. The beam reinforced with a vertical steel plate considerably presented a bond force higher than the beam reinforced with a horizontal steel plate.

Keywords: bond, pullout, reinforced concrete, steel plate

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Authors: Reza Ziaie Moayed, Javad Shamsi Soosahab

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The bearing capacity of shallow foundations is one of the interesting subjects in geotechnical engineering. Soil improvement by geosynthetic reinforcements is a modern method used in different projects to improve the bearing capacity of foundations. In this paper, numerical study is adopted to investigate the effect of geogrid soil reinforcement on shallow foundation behavior resting on anisotropic sand with using a finite element limit analysis software. The effect of the ratio of horizontal elastic modulus with respect to vertical elastic modulus (EH/EV) investigates on bearing capacity of foundations. The results illustrate that in sandy soils, the anisotropic ratio of elastic modulus (EH/EV) has notable effect on bearing capacity of shallow foundations. Also, based on the results of this study, it was concluded that geogrid could be used as soil reinforcement elements to improve the bearing of sandy soils and reduce its settlement possible remarkably.

Keywords: shallow foundations, bearing capacity, numerical study, soil anisotropy, geogrid

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Authors: R. Ziaie Moayed, A. Khalili

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Improvement and reinforcement of soils with poor strength and engineering properties for constructing low height structures or structures such as liquid storage tanks, bridge columns, and heavy structures have necessitated applying particular techniques. Stone columns are among the well-known methods applied in such soils. This method provides an economically justified way for improving engineering properties of soft clay and loose sandy soils. Stone column implementation in these soils increases their bearing capacity and reduces the settlement of foundation build on them. In the present study, the finite difference based FLAC3D software was used to investigate the performance and effect of soil reinforcement through stone columns without lining and those with geosynthetic lining with different levels of stiffness in horizontal and vertical modes in clayey soils. The results showed that soil improvement using stone columns with lining in vertical and horizontal modes results in improvement of bearing capacity and foundation settlement.

Keywords: bearing capacity, FLAC3D, geosynthetic, settlement, stone column

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Authors: Abbas Teimouri, Leila Ghorbanian, Iren Dabirian

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This work focused on preparation and characterizations of silk fibroin (SF)/nanodiopside nanoceramic via electrospinning process. Nanofibrous scaffolds were characterized by combined techniques of scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). The results confirmed that fabricated SF/diopside scaffolds improved cell attachment and proliferation. The results indicated that the electrospun of SF/nanodiopside nanofibrous scaffolds could be considered as ideal candidates for tissue engineering.

Keywords: electrospinning, nanofibers, silk fibroin, diopside, composite scaffold

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Authors: S. Boria

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In the last years, the crashworthiness of an automotive body structure can be improved, since the beginning of the design stage, thanks to the development of specific optimization tools. It is well known how the finite element codes can help the designer to investigate the crashing performance of structures under dynamic impact. Therefore, by coupling nonlinear mathematical programming procedure and statistical techniques with FE simulations, it is possible to optimize the design with reduced number of analytical evaluations. In engineering applications, many optimization methods which are based on statistical techniques and utilize estimated models, called meta-models, are quickly spreading. A meta-model is an approximation of a detailed simulation model based on a dataset of input, identified by the design of experiments (DOE); the number of simulations needed to build it depends on the number of variables. Among the various types of meta-modeling techniques, Kriging method seems to be excellent in accuracy, robustness and efficiency compared to other ones when applied to crashworthiness optimization. Therefore the application of such meta-model was used in this work, in order to improve the structural optimization of a bumper for a racing car in composite material subjected to frontal impact. The specific energy absorption represents the objective function to maximize and the geometrical parameters subjected to some design constraints are the design variables. LS-DYNA codes were interfaced with LS-OPT tool in order to find the optimized solution, through the use of a domain reduction strategy. With the use of the Kriging meta-model the crashworthiness characteristic of the composite bumper was improved.

Keywords: composite material, crashworthiness, finite element analysis, optimization

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Authors: Radha H. R., Krupakara P. V.

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Metal matrix composites are attracting today's manufacturers of many automobile parts so that they lost longer and their properties can be tailored according to the requirement. In this paper an attempt has been made to study the corrosion characteristics of Aluminium 6061 / quartz metal matrix composites in alkali medium like sodium hydroxide solutions. Metal matrix composites are heterogeneous mixtures of a matrix and reinforcement. In this work the matrix selected is Aluminium 6061 alloy which is commercially available and the reinforcement selected is quartz particulates of 50-80 micron size which is available in plenty in and around Bangalore district, India. Composites containing Aluminium 6061 with 2, 4 and 6 weight percent of quartz are manufactured by liquid melt metallurgy technique using vortex method. Corrosion tests like static weight loss and open circuit potential tests are conducted in different concentrated solutions of sodium hydroxide. To compare the results the matrix Aluminium 6061 is also casted in the same way. Specimens for the test are prepared according to ASTM standards. In all the tests the metal matrix composites showed better corrosion resistance than matrix alloy.

Keywords: aluminium 6061, corrosion, quartz, vortex

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Authors: Chi Zhang, Hua-Peng Chen

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With the increasingly demanding resources in the word, renewable and clean energy has been considered as an alternative way to replace traditional ones. Thus, one of practical examples for using wind energy is wind turbine, which has gained more attentions in recent research. Like most offshore structures, the blades, which is the most critical components of the wind turbine, will be subjected to millions of loading cycles during service life. To operate safely in marine environments, the blades are typically made from fibre reinforced composite materials to resist fatigue delamination and harsh environment. The fatigue crack development of blades is uncertain because of indeterminate mechanical properties for composite and uncertainties under offshore environment like wave loads, wind loads, and humid environments. There are three main delamination failure modes for composite blades, and the most common failure type in practices is subjected to mixed mode loading, typically a range of opening (mode 1) and shear (mode 2). However, the fatigue crack development for mixed mode cannot be predicted as deterministic values because of various uncertainties in realistic practical situation. Therefore, selecting an effective stochastic model to evaluate the mixed mode behaviour of wind turbine blades is a critical issue. In previous studies, gamma process has been considered as an appropriate stochastic approach, which simulates the stochastic deterioration process to proceed in one direction such as realistic situation for fatigue damage failure of wind turbine blades. On the basis of existing studies, various Paris Law equations are discussed to simulate the propagation of the fatigue crack growth. This paper develops a Paris model with the stochastic deterioration modelling according to gamma process for predicting fatigue crack performance in design service life. A numerical example of wind turbine composite materials is investigated to predict the mixed mode crack depth by Paris law and the probability of fatigue failure by gamma process. The probability of failure curves under different situations are obtained from the stochastic deterioration model for comparisons. Compared with the results from experiments, the gamma process can take the uncertain values into consideration for crack propagation of mixed mode, and the stochastic deterioration process shows a better agree well with realistic crack process for composite blades. Finally, according to the predicted results from gamma stochastic model, assessment strategies for composite blades are developed to reduce total lifecycle costs and increase resistance for fatigue crack growth.

Keywords: Reinforced fibre composite, Wind turbine blades, Fatigue delamination, Mixed failure mode, Stochastic process.

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Authors: A. Mimaroglu, H. Unal

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In this study, the mechanical properties of nano filled epoxy composites were evaluated. The matrix material is epoxy. nano fillers are Al2O3, TiO2 and clay added in 2.5- 10 wt% by weight ratio. Test samples were prepared using an open mould type die. Mechanical tests were carried out. The tensile strength, elastic modulus, elongation at break and the hardness of the composite materials were obtained and evaluated. It was seen from the results that the filler content had a high influence on the level of the mechanical properties of the epoxy composites.

Keywords: nano, epoxy, composite, fillers, clay

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Authors: Michael Tupý, Alice Tesaříková-Svobodová, Dagmar Měřínská, Vít Petránek

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Polyethylene (PE), Polypropylene (PP), Polyethylene (vinyl acetate) (EVA) and Surlyn (modif-PE) nano composite samples were prepared with montmorillonite fillers Cloisite 93A and Dellite 67G. The amount of modified Na+ montmorillonite (MMT) was fixed to 5 % (w/w). For the compounding of polymer matrix and chosen nano fillers twin-screw kneader was used. The level of MMT intercalation or exfoliation in the nano composite systems was studied by transmission electron microscopy (TEM) observations. The properties of samples were evaluated by dynamical mechanical analysis (E* modulus at 30 °C) and by the measurement of tensile properties (stress and strain at break).

Keywords: polyethylene, polypropylene, polyethylene(vinyl acetate), clay, nanocomposite, montmorillonite

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Authors: A. Gherbi, L. Dahmani, A. Boudjemia

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This paper presents the Finite Element Method (FEM) for analyzing the failure pattern of rectangular slab with various edge conditions. Non-Linear static analysis is carried out using ANSYS 15 Software. Using SOLID65 solid elements, the compressive crushing of concrete is facilitated using plasticity algorithm, while the concrete cracking in tension zone is accommodated by the nonlinear material model. Smeared reinforcement is used and introduced as a percentage of steel embedded in concrete slab. The behavior of the analyzed concrete slab has been observed in terms of the crack pattern and displacement for various loading and boundary conditions. The finite element results are also compared with the experimental data. One of the other objectives of the present study is to show how similar the crack path found by ANSYS program to those observed for the yield line analysis. The smeared reinforcement method is found to be more practical especially for the layered elements like concrete slabs. The value of this method is that it does not require explicit modeling of the rebar, and thus a much coarser mesh can be defined.

Keywords: ANSYS, cracking pattern, displacements, reinforced concrete slab, smeared reinforcements

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Authors: Ehsan Sadie

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Today, after devastating earthquakes and many deaths due to the destruction of residential buildings, the scientific community has attracted the attention of the existing structures to strengthen and standardize construction. Due to the fact that the existing buildings are sometimes constructed without sufficient knowledge of the correct design, and even the buildings built according to the old standards today need to be reinforced due to changes in some provisions of the regulations. The location of some countries in the seismic zone has always caused a lot of human and economic damage throughout history, and attention to the strengthening of buildings, important facilities, and vital arteries is the result of this situation. Engineers' efforts to design earthquake-resistant buildings began when decades had passed since the development of design criteria and ensuring the safety of buildings against loads. New methods, mass reduction, reducing the weight of the building, use of moving structures to deal with earthquakes, as well as the use of new technologies in this field, including the use of dampers, composites in the reinforcement of structures are discussed, and appropriate solutions have been provided in each of the fields.

Keywords: brace, concrete structure, damper, earthquake, FRP reinforcement, lightweight material, retrofitting, seismic isolator, shear wall, steel structure

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Authors: Watchareeporn Chaimongkol

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In this paper, we compare the statistical measures accuracy of composite forecasting model to estimate automobile customer demand in Thailand. A modified simple exponential smoothing and autoregressive integrate moving average (ARIMA) forecasting model is built to estimate customer demand of passenger cars, instead of using information of historical sales data. Our model takes into account special characteristic of the Thai automobile market such as sales promotion, advertising and publicity, petrol price, and interest rate for loan. We evaluate our forecasting model by comparing forecasts with actual data using six accuracy measurements, mean absolute percentage error (MAPE), geometric mean absolute error (GMAE), symmetric mean absolute percentage error (sMAPE), mean absolute scaled error (MASE), median relative absolute error (MdRAE), and geometric mean relative absolute error (GMRAE).

Keywords: composite forecasting, simple exponential smoothing model, autoregressive integrate moving average model selection, accuracy measurements

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Authors: Xueming Xu, Jiahao Liu, Jichao Li, Kewei Yang, Minghao Li, Bingfeng Ge

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A combat system-of-systems (CSoS) comprises various types of functional combat entities that interact to meet corresponding task requirements in the present and future. Enhancing the resilience of CSoS holds significant military value in optimizing the operational planning process, improving military survivability, and ensuring the successful completion of operational tasks. Accordingly, this research proposes an integrated framework called CSoS resilience enhancement (CSoSRE) to enhance the resilience of CSoS from a recovery perspective. Specifically, this research presents a two-phase resilience optimization model to define a resilience optimization objective for CSoS. This model considers not only task baseline, recovery cost, and recovery time limit but also the characteristics of emergency recovery and comprehensive recovery. Moreover, the research extends it from the deterministic case to the stochastic case to describe the uncertainty in the recovery process. Based on this, a resilience-oriented recovery optimization method based on deep reinforcement learning (RRODRL) is proposed to determine a set of entities requiring restoration and their recovery sequence, thereby enhancing the resilience of CSoS. This method improves the deep Q-learning algorithm by designing a discount factor that adapts to changes in CSoS state at different phases, simultaneously considering the network’s structural and functional characteristics within CSoS. Finally, extensive experiments are conducted to test the feasibility, effectiveness and superiority of the proposed framework. The obtained results offer useful insights for guiding operational recovery activity and designing a more resilient CSoS.

Keywords: combat system-of-systems, resilience optimization model, recovery optimization method, deep reinforcement learning, certainty and uncertainty

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Authors: Fashad Amini, Lin Li

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High performance turf reinforcement mat (HPTRM) is one of the most advanced flexible armoring technologies for severe erosion challenges. The effect of turbulence on the slope stability of an earthen levee strengthened by high performance turf reinforcement mat (HPTRM) is investigated in this study for combined storm surge and wave overtopping conditions. The results show that turbulence has strong influence on the slope stability during the combined storm surge and wave overtopping conditions. Among the surge height, peak wave force and turbulent force. The turbulent force has the ability to stabilize the earthen levee at the large wave force the turbulent force has strongest effect on the FS. The surge storm acts as an independent force on the slope stability of the earthen levee. It just adds to the effects of the turbulent force and wave force on the slope stability of HPTRM strengthened levee.

Keywords: slope stability, strength reduction method, HPTRM, levee, overtopping

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Authors: Ines Antunes, Andrea Massari, Concetta Bartucca

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Greenhouse gasses (GHG) role in the atmosphere has been well known since the 19th century; however, researchers have begun to relate them to climate changes only in the second half of the following century. From this moment, scientists started to correlate the presence of GHG such as CO₂ with the global warming phenomena. This has raised the awareness not only of those who were experts in this field but also of public opinion, which is becoming more and more sensitive to environmental pollution and sustainability issues. Nowadays the reduction of GHG emissions is one of the principal objectives of EU nations. The target is an 80% reduction of emissions in 2050 and to reach the important goal of carbon neutrality. Road sector is responsible for an important amount of those emissions (about 20%). The most part is due to traffic, but a good contribution is also given directly or indirectly from road construction and maintenance. Raw material choice and reuse of post-consumer plastic rather than a cleverer design of roads have an important contribution to reducing carbon footprint. Bituminous membranes can be successfully used as reinforcement systems in asphalt layers to improve road pavement performance against cracking. Composite materials coupling membranes with grids and/or fabrics should be able to combine improved tensile properties of the reinforcement with stress absorbing and waterproofing effects of membranes. Polyglass, with its brand dedicated to road construction and maintenance called Polystrada, has done more than this. The company's target was not only to focus sustainability on the final application but also to implement a greener mentality from the cradle to the grave. Starting from production, Polyglass has made important improvements finalized to increase efficiency and minimize waste. The installation of a trigeneration plant and the usage of selected production scraps inside the products as well as the reduction of emissions into the environment, are one of the main efforts of the company to reduce impact during final product build-up. Moreover, the benefit given by installing Polystrada products brings a significant improvement in road lifetime. This has an impact not only on the number of maintenance or renewal that needs to be done (build less) but also on traffic density due to works and road deviation in case of operations. During the end of the life of a road, Polystrada products can be 100% recycled and milled with classical systems used without changing the normal maintenance procedures. In this work, all these contributions were quantified in terms of CO₂ emission thanks to an LCA analysis. The data obtained were compared with a classical system or a standard production of a membrane. What it is possible to see is that the usage of Polyglass products for street maintenance and building gives a significant reduction of emissions in case of membrane installation under the road wearing course.

Keywords: CO₂ emission, LCA, maintenance, sustainability

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Authors: Z. Ansari, M. R. M. Rejab, D. Bachtiar, J. P. Siregar

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This study focus on the compression and tensile properties of new and recycle square honeycombs structure from sugar palm fibre (SPF) and polylactic acid (PLA) composite. The end data will determine the failure strength and energy absorption for both new and recycle composite. The control SPF specimens were fabricated from short fibre co-mingled with PLA by using a bra-blender set at 180°C and 50 rpm consecutively. The mixture of 30% fibre and 70% PLA were later on the hot press at 180°C into sheets with thickness 3mm consecutively before being assembled into a sandwich honeycomb structure. An INSTRON tensile machine and Abaqus 6.13 software were used for mechanical test and finite element simulation. The percentage of error from the simulation and experiment data was 9.20% and 9.17% for both new and recycled product. The small error of percentages was acceptable due to the nature of the simulation model to be assumed as a perfect model with no imperfect geometries. The energy absorption value from new to recycled product decrease from 312.86kJ to 282.10kJ. With this small decrements, it is still possible to implement a recycle SPF/PLA composite into everyday usages such as a car's interior or a small size furniture.

Keywords: failure modes, numerical modelling, polylactic acid, sugar palm fibres

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Authors: Mochamad Chalid, Imam Prabowo

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The pollution due to non-degradable material such as plastics, has led to studies about the development of environmental-friendly material. Because of biodegradability obtained from natural sources, polylactid acid (PLA) and ijuk fiber are interesting to modify into a composite. This material is also expected to reduce the impact of environmental pollution. Surface modification of ijuk fiber through alkalinization with 0.25 M NaOH solution for 30 minutes, was aimed to enhance it’s compatibility to PLA, in order to improve properties of the composite such as the mechanical properties. Alkalinization of the ijuk fibers annihilates some surface components such as lignin, wax and hemicelloluse, so the pore on the surface clearly appeared, decreasing of the density and diameter of the ijuk fibers. The change of the ijuk fiber properties leads to increase the mechanical properties of PLA composites reinforced the ijuk fibers through strengthening of the mechanical interlocking with the PLA matrix. An addition to enhance the distribution of the fibers in the PLA matrix, the stirring during DCM solvent evaporation from the mixture of the ijuk fibers and the dissolved-PLA can reduce amount of the trapped-voids and fibers pull-out phenomena, which can decrease the mechanical properties of the composite.

Keywords: polylactic acid, Arenga pinnata, alkalinization, compatibility, adhesion, morphology, mechanical properties, volume fraction, distributiom

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Authors: Ngozi Nwogu, Godson Osueke, Mamdud Hossain, Edward Gobina

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An unconventional composite inorganic ceramic membrane capable in carbon dioxide emission decline was fabricated and tested at laboratory scale to develop in conformism to various environmental guidelines to mitigate the effect of global warming. A review of the existing membrane technologies for carbon capture including the relevant gas transport mechanisms are presented and discussed. Single gas separation experiments using silica modified ceramic membrane with internal diameter 20mm, outside diameter 25mm and length of 368mm deposited on a macro porous supported reactor.was carried out to investigate individual gas permeation behaviours at different pressures and membrane efficiency after a dip coating method. Nitrogen, Carbon dioxide, Argon, Oxygen and Methane pure gases were used to investigate their individual permeation rates at various pressures. Results show that the gas flow rate increases with pressure drop. However at above a pressure of 3bar, CO2 permeability ratio to than the other gases indicated control of a more selective surface adsorptive transport mechanism.

Keywords: carbon dioxide, composite membranes, permeability, transport mechanisms

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Authors: Sergei Zhevnenko

Abstract:

Сontinuous layer of tantalum boride is formed on the surface as a result of reactive wetting of oxidized tantalum by copper melt with boron at a temperatures above 1150 °C. An increase in the wetting temperature above 1400 °C leads to a change in the formation mechanism of tantalum borides, they are formed in the nanosized flakes. In the presented work, we studied the process of copper-based in-situ composite formation, strengthened by the particles of tantalum borides. We investigated the structure of the formed particles, the conditions, and the kinetics of their formation. Dissolving boride particles do not have time to mix uniformly in the melt upon sufficiently rapid cooling and form a macrostructure, partly repeating the shape of the metallic tantalum. This allows to set different gradient structures in the copper alloy. Such macrostructures have been obtained. Boride particles and microstructures were studied by scanning and transmission electron microscopy, and regions with particles were investigated by nanoindentation. In this work, we also measured the kinetics of impregnation of porous tantalum with copper-boron melt and studied the structures of the composite, in which the melt filling the interpore space is saturated with boride particles.

Keywords: copper, tantalum borides, in-situ composites, wetting, imbibition

Procedia PDF Downloads 103

Authors: Z. Kassab, A. Aboulkas, A. Barakat, M. El Achaby

Abstract:

The red algae are available enormously around the world and their exploitation for the production of agar product has become as an important industry in recent years. However, this industrial processing of red algae generated a large quantity of solid fibrous wastes, which constitute a source of a serious environmental problem. For this reason, the exploitation of this solid waste would help to i) produce new value-added materials and ii) to improve waste disposal from environment. In fact, this solid waste can be fully utilized for the production of cellulose microfibers and nanocrystals because it consists of large amount of cellulose component. For this purpose, the red algae waste was chemically treated via alkali, bleaching and acid hydrolysis treatments with controlled conditions, in order to obtain pure cellulose microfibers and cellulose nanocrystals. The raw product and the as-extracted cellulosic materials were successively characterized using serval analysis techniques, including elemental analysis, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy and transmission electron microscopy. As an application, the as extracted cellulose nanocrystals were used as nanofillers for the production of polymer-based composite films with improved thermal and tensile properties. In these composite materials, the adhesion properties and the large number of functional groups that are presented in the CNC’s surface and the macromolecular chains of the polymer matrix are exploited to improve the interfacial interactions between the both phases, improving the final properties. Consequently, the high performances of these composite materials can be expected to have potential in packaging material applications.

Keywords: cellulose nanowhiskers, food packaging, polymer composites, red algae waste

Procedia PDF Downloads 228

Authors: Júlia Cristina Bonaldo, Christophe L. Martin, Martiniano Piccico, Keith Beale, Roop Kishore, Severine Romero-Baivier

Abstract:

Refractory composite materials employed in steel casting applications are prone to cracking and material damage because of the very high operating temperature (thermal shock) and mismatched properties of the constituent phases. The fracture behavior of a model MgO-C composite refractory is investigated to quantify and characterize its thermal shock resistance, employing a cold crushing test and Brazilian test with fractographic analysis. The discrete element method (DEM) is used to generate numerical refractory composites. The composite in DEM is represented by an assembly of bonded particle clusters forming perfectly spherical aggregates and single spherical particles. For the stresses to converge with a low standard deviation and a minimum number of particles to allow reasonable CPU calculation time, representative volume element (RVE) numerical packings are created with various numbers of particles. Key microscopic properties are calibrated sequentially by comparing stress-strain curves from crushing experimental data. Comparing simulations with experiments also allows for the evaluation of crack propagation, fracture energy, and strength. The crack propagation during Brazilian experimental tests is monitored with digital image correlation (DIC). Simulations and experiments reveal three distinct types of fracture. The crack may spread throughout the aggregate, at the aggregate-matrix interface, or throughout the matrix.

Keywords: refractory composite, fracture mechanics, crack propagation, DEM

Procedia PDF Downloads 81