Advances in Materials Science and Engineering https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Strength and Stiffness of Stabilized Alluvial Silt under Frost Actions Mon, 27 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/5605471/ The Yellow River alluvial silt was stabilized into pavement base materials for cold regions. The stabilizing additives were cement, fly ash, and lime, which were included in a range of combinations and dosages when mixed with the silt. Freeze-thaw cyclic impacts were conducted on the treated samples to assess materials performance of withstanding the frost actions. The tests were conducted on samples cured for 7 days to up to 180 days. Test results show that the cement-fly ash-treated samples outperform the other two stabilization categories with respect to material strength and stiffness developed under both normal and frost conditions. Under the normal conditions, the material unconfined compressive (UC) strength rises to 3.0 MPa on day 28 depending on the cement and fly ash dosage used. If subjected to frost actions, the fly ash inclusions warrant a residual UC strength value of 1.3 MPa and above. The antifrost performance of the cement-fly ash-treated samples is related to thermal buffer capacity of the fly ash particles. Water adsorption and material soundness results agree with the strength and stiffness development. An optimal dosage was 3–6% for the cement and 0.3 for cement to fly ash mass ratio. Haibo Wang, An Deng, and Ping Yang Copyright © 2017 Haibo Wang et al. All rights reserved. Study of Mechanical and Tribological Properties of Nanomica Dispersed Hydroxyapatite Based Composites for Biomedical Applications Sun, 26 Feb 2017 09:32:07 +0000 http://www.hindawi.com/journals/amse/2017/9814624/ Present research aims to assess the influence of nanocrystalline mica (NM) dispersion (10, 15, 20, and 25 vol.%) in hydroxyapatite (HA) matrix on its mechanical and tribological properties and bioactivity. Nanosized mica (NM) was prepared by mechanical milling of commercial mica powder. The composite was prepared by mechanically mixing the milled mica with HA and consolidated by microwave sintering at 1200°C for 10 min. Phase characterization by X-ray diffraction (XRD) shows dissociation of HA into β-TCP (tetra calcium phosphate) in sintered compact. Estimated densification is the highest (~98%) with 20% NM addition. HA-20%NM also shows an optimum combination of mechanical (hardness 2.80 GPa and indentation fracture toughness 1.51 MPa m1/2) and tribological properties (wear rate ~1.6 × 10−6 mm3/Nm). Scanning electron microscopy (SEM) of worn out surface elicits that wear mechanism is governed mainly by delamination and abrasive mode. Biocompatibility assessment in simulated body fluid (SBF) indicates that no elemental change occurs (confirmed by energy dispersive spectroscopy (EDS)) even after 60 days of emersion. It reveals that the optimized composition is satisfying fundamental requirements of an implant material. Anumeha Mishra, Nidhi Khobragade, Koushik Sikdar, Subhabrata Chakraborty, Sashi Bhusan Kumar, and Debdas Roy Copyright © 2017 Anumeha Mishra et al. All rights reserved. Fatigue Performance of Recycled Hot Mix Asphalt: A Laboratory Study Sun, 26 Feb 2017 09:17:35 +0000 http://www.hindawi.com/journals/amse/2017/4397957/ The paper introduces and analyses the results of an experimental trial on the fatigue resistance of recycled hot mix asphalt for road pavements. Based on the gyratory compaction and the indirect tensile strength test, the mix design procedure has optimized nine different mixes, considering both conventional limestone and Reclaimed Asphalt Pavement (RAP), the latter used at different quantities, up to 40% by weight of the aggregate. A standard bitumen and two polymer modified binders were used for the production of the mixes. The fatigue study was carried out with four-point bending tests, each one performed at 20°C and 10 Hz. The empirical stiffness reduction method, along with the energy ratio approach, based on the dissipated energy concept, was adopted to elaborate the experimental data. Unaged and aged specimens were checked, to analyse the ageing effects on the fatigue performance. In comparison with the control mixes, produced only with limestone, improved fatigue performance was noticed for the mixtures prepared with RAP, especially when made with polymer modified binders, under both aged and unaged conditions. Both the approaches adopted for the experimental data analysis have outlined the same ranking of the mixes. Marco Pasetto and Nicola Baldo Copyright © 2017 Marco Pasetto and Nicola Baldo. All rights reserved. Influence of Surface Energy Effects on Elastic Fields of a Layered Elastic Medium under Surface Loading Sun, 26 Feb 2017 08:38:33 +0000 http://www.hindawi.com/journals/amse/2017/7530936/ This paper presents the analysis of a layered elastic half space under the action of axisymmetric surface loading and the influence of the surface energy effects. The boundary value problems for the bulk and the surface are formulated based on classical linear elasticity and a complete Gurtin-Murdoch constitutive relation. An analytical technique using Love’s representation and the Hankel integral transform is employed to derive an integral-form solution for both displacement and stress fields. An efficient numerical quadrature is then applied to accurately evaluate all involved integrals. Selected numerical results are presented to portray the influence of various parameters on elastic fields. Numerical results indicate that the surface stress displays a significant influence on both displacement and stress fields. It is also found that the layered half space becomes stiffer with the presence of surface stresses. In addition, unlike the classical elasticity solution, size-dependent behavior of elastic fields is noted. The present analytical solutions provide fundamental understanding of the influence of surface energy on layered elastic materials. It can also be used as a benchmark solution for the development of numerical techniques such as FEM and BEM, for analysis of more complex problems involving a layered medium under the influence of surface energy effects. Supakorn Tirapat, Teerapong Senjuntichai, and Jaroon Rungamornrat Copyright © 2017 Supakorn Tirapat et al. All rights reserved. Investigations on the Hot Stamping of AW-7921-T4 Alloy Sheet Sun, 26 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/7679219/ AW-7xxx alloys have been nowadays considered for greater light weighting potential in automotive industry due to its higher strength compared to AW-5xxx and AW-6xxx alloys. However, due to their lower formability the forming processes are still in development. This paper investigates one such forming process called hot stamping. The investigation started by carrying out hot tensile testing of an AW-7xxx alloy, that is, AW-7921 at temperatures between 350°C and 475°C, to measure the strength and formability. Formability was found to improve with increasing temperature and was sensitive to the strain rate. Dynamic recovery is considered as usual reason for the formability improvement. However, examining the precipitation states of the as-received condition and after hot stamping using differential scanning calorimetry (DSC), the dissolution of precipitates was also believed to contribute to this increase in formability. Following solution heat treatment there was no precipitation during cooling across the cooling rates investigated (5–10°C/s). Samples taken from parts hot stamped at 10 and 20 mm s−1 had similar yield strengths. A 3-step paint baking heat treatment yielded a higher postpaint baking strength than a single step treatment. M. Kumar and N. G. Ross Copyright © 2017 M. Kumar and N. G. Ross. All rights reserved. An Electrochemical Study to Evaluate the Effect of Calcium Nitrite Inhibitor to Mitigate the Corrosion of Reinforcement in Sodium Chloride Contaminated Ca(OH)2 Solution Thu, 23 Feb 2017 12:31:13 +0000 http://www.hindawi.com/journals/amse/2017/6265184/ The effect of calcium nitrite (Ca(NO2)2) was assessed by electrochemical means such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic studies in saturated Ca(OH)2 solution contaminated with 0.99 and 7.91 g/L NaCl. The preliminary results of OCP showed that the potential is shifted towards positive (noble) side as content of inhibitor increased. The EIS results indicate that Ca(NO2)2 works effectively in reduction and initiation of corrosion of steel rebar in NaCl contaminated Ca(OH)2 solution. Potentiodynamic studies revealed the pitting tendency of steel rebar exposed in 0.99 g/L NaCl at [Cl−/] = 1.2 attributed to low conductivity of passive film which causes interference for Cl− ions attack during anodic polarization. The 85.75% efficiency is found in 0.99 g/L at [Cl−/] = 1.2. The Ca(NO2)2 inhibitor transformed the unstable iron oxides/hydroxides into stable and protective oxides/hydroxides due to its strong oxidizing nature. Therefore, this inhibitor is sufficiently and significantly reducing the corrosion of steel rebar at even its low concentration with 0.99 and 7.91 g/L NaCl solution. Hwa-Sung Ryu, Jitendra Kumar Singh, Han-Seung Lee, and Won-Jun Park Copyright © 2017 Hwa-Sung Ryu et al. All rights reserved. Analysis of Step Responses in Nonlinear Dynamic Systems Consisting of Antagonistic Involvement of Pneumatic Artificial Muscles Wed, 22 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/7168462/ The paper describes a set of experimental measurements carried out on the experimental equipment with a drive based on pneumatic artificial muscles. Based on the analysis of the PAMS control systems issue in relation to the issue of a position control, a control algorithm has been designed and verified. The requirements of the control systems do not arise only from the condition of the desired positioning point rapid achievement, but also from the subsequent dynamics and accuracy repeatability. This algorithm enables an efficient way of stabilization of the actuator position in various dynamic conditions during the operation. It allows eliminating undesirable vibrations oscillating around the point of the required position and dampening them appropriately. The article describes a set of performed verification experimental measurements confirming the applicability in relation to the system that controls the position of the actuator utilizing the described algorithm. The algorithm application enables a positive influencing and optimization of the actuator positioning accuracy and a full-valued automation of its operation. Miroslav Rimár, Peter Šmeringai, Marcel Fedak, Michal Hatala, and Andrii Kulikov Copyright © 2017 Miroslav Rimár et al. All rights reserved. Properties of Direct Coal Liquefaction Residue Modified Asphalt Mixture Tue, 21 Feb 2017 09:31:41 +0000 http://www.hindawi.com/journals/amse/2017/2473283/ The objectives of this paper are to use Direct Coal Liquefaction Residue (DLCR) to modify the asphalt binders and mixtures and to evaluate the performance of modified asphalt mixtures. The dynamic modulus and phase angle of DCLR and DCLR-composite modified asphalt mixture were analyzed, and the viscoelastic properties of these modified asphalt mixtures were compared to the base asphalt binder SK-90 and Styrene-Butadiene-Styrene (SBS) modified asphalt mixtures. The master curves of the asphalt mixtures were shown, and dynamic and viscoelastic behaviors of asphalt mixtures were described using the Christensen-Anderson-Marasteanu (CAM) model. The test results show that the dynamic moduli of DCLR and DCLR-composite asphalt mixtures are higher than those of the SK-90 and SBS modified asphalt mixtures. Based on the viscoelastic parameters of CAM models of the asphalt mixtures, the high- and low-temperature performance of DLCR and DCLR-composite modified asphalt mixtures are obviously better than the SK-90 and SBS modified asphalt mixtures. In addition, the DCLR and DCLR-composite modified asphalt mixtures are more insensitive to the frequency compared to SK-90 and SBS modified asphalt mixtures. Jie Ji, Hui Yao, Di Wang, Zhi Suo, Luhou Liu, and Zhanping You Copyright © 2017 Jie Ji et al. All rights reserved. High Stability Performance of Superhydrophobic Modified Fluorinated Graphene Films on Copper Alloy Substrates Sun, 19 Feb 2017 08:48:51 +0000 http://www.hindawi.com/journals/amse/2017/6197872/ A stable self-cleaning superhydrophobic modified fluorinated graphene surface with micro/nanostructure was successfully fabricated on copper substrates via drop coating process. Irregularly stacked island-like multilayered fluorinated graphene nanoflakes comprised the microstructure. The fabricated films exhibited outstanding superhydrophobic property with a water contact angle 167° and water sliding angle lower than 4°. The developed superhydrophobic surface showed excellent corrosion resistance with insignificant decrease of water contact angle 166° in 3.5 wt.% NaCl solution. This stable highly hydrophobic performance of the fluorinated graphene films could be useful in self-cleaning, antifogging, corrosion resistive coatings and microfluidic devices. Rafik Abbas, N. Elkhoshkhany, Ahmed Hefnawy, Shaker Ebrahim, and Aya Rahal Copyright © 2017 Rafik Abbas et al. All rights reserved. Nanohydroxyapatite Silicate-Based Cement Improves the Primary Stability of Dental Implants: An In Vitro Study Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/2306025/ Objectives. Insufficient cortical bone volume when placing implants can lead to lack of primary stability. The use of cement as a bone fill material in bone defects around dental implant could result in better clinical outcome. HA has shown excellent biological properties in implant dentistry. The purpose of this study was to evaluate the effect of nanohydroxyapatite powder (Nano-HA) in combination with accelerated Portland cement (APC) on implant primary stability in surgically created circumferential bone defects in a bovine rib in vitro model. Materials and Methods. Sixteen bovine rib bones and thirty-six implants of same type and size (4 mm × 10 mm) were used. Implants were divided into six groups: no circumferential bone defect, defect and no grafting, bone chips grafting, Nano-HA grafting, APC grafting, and Nano-HA mixed to APC grafting (Nano-HA-APC). Circumferential defects around the implants were prepared. The implant stability quotient (ISQ) values were measured before and after the grafting. Results. APC exhibited the highest ISQ values. A significant increase of ISQ values following the grafting of Nano-HA-APC () and APC alone () was achieved. Increase of ISQ values after 72 hours was and , respectively. Nano-HA grafting alone exhibited the least rise in ISQ values. Conclusions. Nanohydroxyapatite silicate-based cement could improve the primary stability of dental implants in circumferential bone defect around implants. Hooman Khorshidi, Saeed Raoofi, Maryam Najafi, Mohammad Hassan Kalantari, Jamshid Khorshidi Malahmadi, and Reza Derafshi Copyright © 2017 Hooman Khorshidi et al. All rights reserved. Evaluation of Materials in a Biomechanical System for Uses in Industrial Lifting Activities Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/3658161/ A biomechanical system is proposed for the emulation of the movement of human arm, leg, and spine movements, as an industry alternative to manage heavy operations in a manufacturing process. The Matlab® programming environment is used as a simulation tool for the analysis and validation of this proposed biomechanism. This machine would reduce the accidents due to human exposure to risky industry environments like the particular one at the host company that we are using as a model for our research. They claim that the accidents in this area alone arise to around thirty percent of the total, causing a decrease in the productivity of the company and other economic losses derived from the worker injuries and insurances. Roberto L. Avitia, Gustavo L. Badilla, Rubén C. Martínez, Jose A. Cárdenas-Haro, Marco A. Reyna, and Miguel E. Bravo-Zanoguera Copyright © 2017 Roberto L. Avitia et al. All rights reserved. The Long Bubbles Penetration through Viscoelastic Fluids with Shear-Thinning Viscosity in a Curved Tube Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/6405872/ The purpose of this research is to investigate the behavior of a long bubbles penetrating through viscoelastic fluids in a curved tube. The injection gas flow is controlled by a mass flow controller (MFC). The results of the experiments show that the bubbles width approaches constant value at the location six-diameter upstream from the bubbles front. A difference variable is introduced at the six-diameter location to show the shifting deviation of the bubbles in the curved tube. It is shown that, with the same fluid viscosity and the curved angle, the difference is higher when the gas flow rate is higher. Also, the difference increases proportionally when the capillary number and the Weissenberg number increase. Ching-Chuan Chang Copyright © 2017 Ching-Chuan Chang. All rights reserved. Chloride Transport in OPC Concrete Subjected to the Freeze and Thaw Damage Thu, 16 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/8212856/ To predict the durability of a concrete structure under the coupling degradation consisting of the frosting and chloride attack, microstructural analysis of the concrete pore structure should be accompanied. In this study, the correlation between the pore structure and chloride migration for OPC concrete was evaluated at the different cement content in the concrete mix accounting for 300, 350, and 400 kg/m3 at 0.45 of a free water cement ratio. The influence of frosting damage on the rate of chloride transport was assessed by testing with concrete specimens subjected to a rapid freezing and thawing cyclic environment. As a result, it was found that chloride transport was accelerated by frost damage, which was more influential at the lower cement content. The microscopic examination of the pore structure showed that the freezing environment increased the volume of the large capillary pore in the concrete matrix. Ki Yong Ann, Min Jae Kim, Jun Pil Hwang, Chang-geun Cho, and Ki Hwan Kim Copyright © 2017 Ki Yong Ann et al. All rights reserved. Electromagnetic Characterization of a Composite (RE-CB-MT) by Time Domain Spectroscopy Thu, 16 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/3571648/ The aim of this article is to study the dielectric behavior (, ) in microwaves domain of composites made with Epoxy Resin (RE), Carbon Black (CB), and Magnesium Titanate (MT) on a large band of frequency. This kind of composites is very solicited for applications and miniaturization of the components circuits (cavities, antennas, substrates, etc.) in hyperfrequency electronics. In this study we have also highlighted the effect of the fillers nature and their concentrations on the behavior of these composites. The results obtained by time domain spectroscopy (TDS) have revealed the strong dependence of complex permittivity of the composite materials on both the nature and the concentration of conductive environment. Low frequency analysis (500 MHz) has been investigated to determine the conductivity of composites which is related to the percolation phenomenon. Moreover, the comparison between experimental results and theoretical models shows that the modeling Lichtenecker law is applicable to the ternary mixture in this frequency range and is in accordance with the approach postulated by Bottreau. Amina Bounar, Nacerdine Bouzit, and Nacerdine Bourouba Copyright © 2017 Amina Bounar et al. All rights reserved. Dynamic Behavior of Clay-Aggregate Mixtures Thu, 16 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/2479507/ Clay-aggregate mixtures are frequently used in engineering practice. To improve the understanding of the effects of coarse particles on the dynamic behavior of clay-aggregate mixtures, series of stress controlled cyclic triaxial tests were performed on clay specimens with various glass bead contents. The results show that the initial shear modulus of clay-aggregate mixtures increased with the increase of the coarse aggregate content and the confining stress. At the confining stress of 100, 200, and 400 kPa, the addition of 32% coarse particles caused an increase in the initial shear modulus of 117%, 110%, and 67%, respectively. Moreover, the normalized shear modulus decreased and damping ratio increased with the coarse aggregate content, and the influence of the confining stress on the strain-dependent dynamic properties was negligible. The specimen with a higher coarse aggregate content was observed to have larger cyclic shear strength and smaller excess pore water pressure, but the effects of the coarse aggregate content became less pronounced under large cyclic stresses. Kang Fei and Jinxin Xu Copyright © 2017 Kang Fei and Jinxin Xu. All rights reserved. An Experimental Study on Solidifying Municipal Sewage Sludge through Skeleton Building Using Cement and Coal Gangue Thu, 16 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/5069581/ The municipal sewage sludge typically has very high water content and low shear strength. Conventional methods of lime and cement solidification of municipal sewage sludge often suffer high cost, significant drying shrinkage, frequent cracking, high hydraulic conductivity, and low strength. To overcome these shortcomings, in this paper a skeleton-building method was used to solidify municipal sewage sludge in which coal gangue, cement and clay, and fiber were used as skeleton materials, cementation materials, and filling materials, respectively. Comprehensive laboratory tests including cracking, nitrogen adsorption, triaxial shearing, and permeability tests were performed to determine cracking, pore structure, shear strength, and hydraulic conductivity of municipal sewage sludge solidified with different proportions of coal gangue, cement, fiber, and clay. Based upon the experimental results, the mechanisms of the skeleton building using cement and coal gangue were discussed and factors controlling the mechanical and hydraulic behavior of the solidified soils were analyzed at both microscopic and macroscopic levels. Based upon the test results and analyses, recommendations were made for solidifying municipal sewage sludge through skeleton building using cement and coal gangue. The solidified soils have high soil strength, high resistance to cracking, and low hydraulic conductivity which are sufficient for being used as landfill liner. Jiankang Yang, Haijun Lu, Xiong Zhang, Jixiang Li, and Weiwei Wang Copyright © 2017 Jiankang Yang et al. All rights reserved. Numerical Analyses of Earthquake Induced Liquefaction and Deformation Behaviour of an Upstream Tailings Dam Wed, 15 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/5389308/ Much of the seismic activity of northern Sweden consists of micro-earthquakes occurring near postglacial faults. However, larger magnitude earthquakes do occur in Sweden, and earthquake statistics indicate that a magnitude 5 event is likely to occur once every century. This paper presents dynamic analyses of the effects of larger earthquakes on an upstream tailings dam at the Aitik copper mine in northern Sweden. The analyses were performed to evaluate the potential for liquefaction and to assess stability of the dam under two specific earthquakes: a commonly occurring magnitude 3.6 event and a more extreme earthquake of magnitude 5.8. The dynamic analyses were carried out with the finite element program PLAXIS using a recently implemented constitutive model called UBCSAND. The results indicate that the magnitude 5.8 earthquake would likely induce liquefaction in a limited zone located below the ground surface near the embankment dikes. It is interpreted that stability of the dam may not be affected due to the limited extent of the liquefied zone. Both types of earthquakes are predicted to induce tolerable magnitudes of displacements. The results of the postseismic slope stability analysis, performed for a state after a seismic event, suggest that the dam is stable during both the earthquakes. Muhammad Auchar Zardari, Hans Mattsson, Sven Knutsson, Muhammad Shehzad Khalid, Maria V. S. Ask, and Björn Lund Copyright © 2017 Muhammad Auchar Zardari et al. All rights reserved. SPR Characteristics Curve and Distribution of Residual Stress in Self-Piercing Riveted Joints of Steel Sheets Wed, 15 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/5824171/ Neutron diffraction was used to describe the residual stress distributions in self-piercing riveted (SPR) joints. The sheet material displayed a compressive residual stress near the joint, and the stress gradually became tensile in the sheet material far away from the joint. The stress in the rivet leg was lower in the thick joint of the softer steel sheet than in the thin joint of the harder steel sheet. This lower magnitude was attributed to the lower force gradient during the rivet flaring stage of the SPR process curve. This study shows how the residual stress results may be related to the physical occurrences that happened during joining, using the characteristics curve. The study also shows that neutron diffraction technique enabled a crack in the rivet tip to be detected which was not apparent from a cross-section. Rezwanul Haque, Yat C. Wong, Anna Paradowska, Stuart Blacket, and Yvonne Durandet Copyright © 2017 Rezwanul Haque et al. All rights reserved. Experimental Study of Dowel Bar Alternatives Based on Similarity Model Test Wed, 15 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/3981908/ In this study, a small-scaled accelerated loading test based on similarity theory and Accelerated Pavement Analyzer was developed to evaluate dowel bars with different materials and cross-sections. Jointed concrete specimen consisting of one dowel was designed as scaled model for the test, and each specimen was subjected to 864 thousand loading cycles. Deflections between jointed slabs were measured with dial indicators, and strains of the dowel bars were monitored with strain gauges. The load transfer efficiency, differential deflection, and dowel-concrete bearing stress for each case were calculated from these measurements. The test results indicated that the effect of the dowel modulus on load transfer efficiency can be characterized based on the similarity model test developed in the study. Moreover, round steel dowel was found to have similar performance to larger FRP dowel, and elliptical dowel can be preferentially considered in practice. Chichun Hu, Jiexian Ma, Jianying Zhao, Zhen Leng, and Denis Jelagin Copyright © 2017 Chichun Hu et al. All rights reserved. Coupling Strategies Investigation of Hybrid Atomistic-Continuum Method Based on State Variable Coupling Tue, 14 Feb 2017 06:22:00 +0000 http://www.hindawi.com/journals/amse/2017/1014636/ Different configurations of coupling strategies influence greatly the accuracy and convergence of the simulation results in the hybrid atomistic-continuum method. This study aims to quantitatively investigate this effect and offer the guidance on how to choose the proper configuration of coupling strategies in the hybrid atomistic-continuum method. We first propose a hybrid molecular dynamics- (MD-) continuum solver in LAMMPS and OpenFOAM that exchanges state variables between the atomistic region and the continuum region and evaluate different configurations of coupling strategies using the sudden start Couette flow, aiming to find the preferable configuration that delivers better accuracy and efficiency. The major findings are as follows: the region plays the most important role in the overlap region and the “4-layer-1” combination achieves the best precision with a fixed width of the overlap region; the data exchanging operation only needs a few sampling points closer to the occasions of interactions and decreasing the coupling exchange operations can reduce the computational load with acceptable errors; the nonperiodic boundary force model with a smoothing parameter of 0.1 and a finer parameter of 20 can not only achieve the minimum disturbance near the MD-continuum interface but also keep the simulation precision. Qian Wang, Xiao-Guang Ren, Xin-Hai Xu, Chao Li, Hong-Yu Ji, and Xue-Jun Yang Copyright © 2017 Qian Wang et al. All rights reserved. SiC Conversion Coating Prepared from Silica-Graphite Reaction Tue, 14 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/6383084/ The β-SiC conversion coatings were successfully synthesized by the SiO(v)-graphite(s) reaction between silica powder and graphite specimen. This paper is to describe the effects on the characteristics of the SiC conversion coatings, fabricated according to two different reaction conditions. FE-SEM, FE-TEM microstructural morphologies, XRD patterns, pore size distribution, and oxidation behavior of the SiC-coated graphite were investigated. In the XRD pattern and SAD pattern, the coating layers showed cubic SiC peak as well as hexagonal SiC peak. The SiC coatings showed somewhat different characteristics with the reaction conditions according to the position arrangement of the graphite samples. The SiC coating on graphite, prepared in reaction zone (2), shows higher intensity of beta-SiC main peak (111) in XRD pattern as well as rather lower porosity and smaller main pore size peak under 1 μm. Back-Sub Sung and Young-Hoon Yun Copyright © 2017 Back-Sub Sung and Young-Hoon Yun. All rights reserved. Modelling of the Water Absorption Kinetics and Determination of the Water Diffusion Coefficient in the Pith of Raffia vinifera of Bandjoun, Cameroon Mon, 13 Feb 2017 12:57:13 +0000 http://www.hindawi.com/journals/amse/2017/1953087/ The present work focuses on the study of the water absorption phenomenon through the pith of Raffia vinifera along the stem. The water absorption kinetics was studied experimentally by the gravimetric method with the discontinuous control of the sampling mass at temperature of 30°C. The samples of 70 mm × 8 mm × 4 mm were taken from twelve sampling zones of the stem of Raffia vinifera. The result shows that the percentage of water absorption of the pith of Raffia vinifera increases from the periphery to the center in the radial position and from the base to the leaves in the longitudinal position. Fick’s second law was adopted for the study of the water diffusion. Eleven models were tested for the modelling of the water absorption kinetics and the model of Sikame Tagne (2014) is the optimal model. The diffusion coefficients of two stages were determined by the solution of the Fick equation in the twelve sampling zones described by Sikame Tagne et al. (2014). The diffusion coefficients decreased from the center to the periphery in the radial position and from the base to the leaves in the longitudinal position. E. Tiaya Mbou, E. Njeugna, A. Kemajou, N. R. Tagne Sikame, and D. Ndapeu Copyright © 2017 E. Tiaya Mbou et al. All rights reserved. Mechanical and Failure Criteria of Air-Entrained Concrete under Triaxial Compression Load after Rapid Freeze-Thaw Cycles Mon, 13 Feb 2017 08:55:35 +0000 http://www.hindawi.com/journals/amse/2017/6786270/ The experiment study on the air-entrained concrete of 100 mm cubes under triaxial compression with different intermediate stress ratio  :  was carried out using a hydraulic-servo testing system. The influence of rapid freeze-thaw cycles and intermediate stress ratio on the triaxial compressive strength was analyzed according to the experimental results, respectively. The experimental results of air-entrained concrete obtained from the study in this paper and the triaxial compression experimental results of plain concrete got through the same triaxial-testing-system were compared and analyzed. The conclusion was that the triaxial compressive strength is greater than the biaxial and uniaxial compressive strength after the same rapid freeze-thaw cycles, and the increased percentage of triaxial compressive strength over biaxial compressive strength or uniaxial compressive strength is dependent on the middle stress. The experimental data is useful for precise analysis of concrete member or concrete structure under the action complex stress state. Feng-kun Cui, Huai-shuai Shang, Tie-jun Zhao, Guo-xi Fan, and Guo-sheng Ren Copyright © 2017 Feng-kun Cui et al. All rights reserved. Multiaxial Cycle Deformation and Low-Cycle Fatigue Behavior of Mild Carbon Steel and Related Welded-Metal Specimen Mon, 13 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/8987376/ The low-cycle fatigue experiments of mild carbon Q235B steel and its related welded-metal specimens are performed under uniaxial, in-phase, and 90° out-of-phase loading conditions. Significant additional cyclic hardening for 90° out-of-phase loading conditions is observed for both base metal and its related weldment. Besides, welding process produces extra additional hardening under the same loading conditions compared with the base metal. Multiaxial low-cycle fatigue strength under 90° out-of-phase loading conditions is significantly reduced for both base-metal and welded-metal specimens. The weldment has lower fatigue life than the base metal under the given loading conditions, and the fatigue life reduction of weldment increases with the increasing strain amplitude. The KBM, FS, and MKBM critical plane parameters are evaluated for the fatigue data obtained. The FS and MKBM parameters are found to show better correlation with fatigue lives for both base-metal and welded-metal specimens. Weilian Qu, Ernian Zhao, and Qiang Zhou Copyright © 2017 Weilian Qu et al. All rights reserved. Flexural Behavior of Concrete Beam Strengthened by Near-Surface Mounted CFRP Reinforcement Using Equivalent Section Model Sun, 12 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/9180624/ FRP (fiber reinforced polymer) has found wide applications as an alternative to steel rebar not only for the repair and strengthening of existing structures but also for the erection of new structures. Near-surface mounted (NSM) strengthening was introduced as an alternative of externally bonded reinforcement (EBR) but this method also experiences early bond failure, which stresses the importance of predicting accurately the bond failure behavior in order to evaluate precisely the performance of NSM reinforcement. This study proposes the equivalent section model assuming monolithic behavior of the filler and CFRP reinforcement. This equivalent section model enables establishing a bond failure model applicable independently of the sectional shape of the CFRP reinforcement. This so-derived bond failure model is then validated experimentally by means of beams flexure-strengthened by NSM CFRP reinforcements with various cross-sections. Finally, analytical analysis applying the bond failure model considering the equivalent section and defined failure criteria is performed. The results show the accuracy of the prediction of the failure mode as well as the accurate prediction of the experimental results regardless of the sectional shape of the CFRP reinforcement. Woo-tai Jung, Jong-sup Park, Jae-yoon Kang, and Moon-seoung Keum Copyright © 2017 Woo-tai Jung et al. All rights reserved. Temperature Characteristics of Porous Portland Cement Concrete during the Hot Summer Session Thu, 09 Feb 2017 09:26:34 +0000 http://www.hindawi.com/journals/amse/2017/2058034/ Pavement heats the near-surface air and affects the thermal comfort of the human body in hot summer. Because of a large amount of connected porosity of porous Portland cement concrete (PPCC), the thermal parameters of PPCC are much different from those of traditional Portland cement concrete (PCC). The temperature change characteristics of PPCC and the effects on surrounding environment are also different. A continuous 48-hour log of temperature of a PCC and five kinds of PPCC with different porosity were recorded in the open air in the hot summer. The air temperatures at different heights above concrete specimens were tested using self-made enclosed boxes to analyze the characteristics of near-surface air temperature. The output heat flux of different concrete specimens was calculated. The results show that the PPCC has higher temperature in the daytime and lower temperature in the nighttime and larger temperature gradient than the PCC. The air temperature above PPCC is lower than that of PCC after solar radiation going to zero at night. The total output heat flux of PPCC is slightly smaller in the daytime and significantly smaller at night than that of PCC. The results of tests and calculations indicate that PPCC contributes to the mitigation of heating effect of pavement on the near-surface air. Liqun Hu, Yangyang Li, Xiaolong Zou, Shaowen Du, Zhuangzhuang Liu, and Hao Huang Copyright © 2017 Liqun Hu et al. All rights reserved. Corrigendum to “Preparation and Characterization of Amorphous B Powders by Salt-Assisted SHS Technique” Wed, 08 Feb 2017 12:37:23 +0000 http://www.hindawi.com/journals/amse/2017/2319424/ Yujing Ou, Peiqing La, Dandan Zhu, and Yalong Zhu Copyright © 2017 Yujing Ou et al. All rights reserved. Metamaterials and Smart Structures in a Big Data Era Wed, 08 Feb 2017 07:43:08 +0000 http://www.hindawi.com/journals/amse/2017/6358497/ Ying Wang, Francesco Dell’Isola, Tiejun Liu, and Chunhui Yang Copyright © 2017 Ying Wang et al. All rights reserved. Intelligent Machine Vision Based Modeling and Positioning System in Sand Casting Process Wed, 08 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/3192672/ Advanced vision solutions enable manufacturers in the technology sector to reconcile both competitive and regulatory concerns and address the need for immaculate fault detection and quality assurance. The modern manufacturing has completely shifted from the manual inspections to the machine assisted vision inspection methodology. Furthermore, the research outcomes in industrial automation have revolutionized the whole product development strategy. The purpose of this research paper is to introduce a new scheme of automation in the sand casting process by means of machine vision based technology for mold positioning. Automation has been achieved by developing a novel system in which casting molds of different sizes, having different pouring cup location and radius, position themselves in front of the induction furnace such that the center of pouring cup comes directly beneath the pouring point of furnace. The coordinates of the center of pouring cup are found by using computer vision algorithms. The output is then transferred to a microcontroller which controls the alignment mechanism on which the mold is placed at the optimum location. Shahid Ikramullah Butt, Umer Asgher, Umar Mushtaq, Riaz Ahmed, Faping Zhang, Yasar Ayaz, Mohsin Jamil, and Muhammad Kamal Amjad Copyright © 2017 Shahid Ikramullah Butt et al. All rights reserved. A Unified Constitutive Model for Creep and Cyclic Viscoplasticity Behavior Simulation of Steels Based on the Absolute Reaction Rate Theory Wed, 08 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/amse/2017/2129478/ In this work, the viscoplasticity and creep behavior for modified 9Cr-1Mo and 316 stainless steels were investigated. Based on the absolute reaction rate theory, a unified constitutive model incorporating internal state variables was proposed to characterize the evolution of the back stress. Also, the model was implemented by the ABAQUS system with the semi-implicit stress integration. Compared to the experimental data, the results demonstrated that the proposed approach could effectively simulate the cyclic softening and hardening behavior for such structural steels. Huayan Chen, Xiangguo Zeng, Yang Guo, and Fang Wang Copyright © 2017 Huayan Chen et al. All rights reserved.