Advances in Materials Science and Engineering The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Studies on Pumice Lightweight Aggregate Concrete with Quarry Dust Using Mathematical Modeling Aid of ACO Techniques Mon, 08 Feb 2016 11:18:18 +0000 The lightweight aggregate is an aggregate that weighs less than the usual rock aggregate and the quarry dust is a rock particle used in the concrete for the experimentation. The significant intention of the proposed technique is to frame a mathematical modeling with the aid of the optimization techniques. The mathematical modeling is done by minimizing the cost and time consumed in the case of extension of the real time experiment. The proposed mathematical modeling is utilized to predict four output parameters such as compressive strength (Mpa), split tensile strength (Mpa), flexural strength (Mpa), and deflection (in mm). Here, the modeling is carried out with three different optimization techniques like genetic algorithm (GA), particle swarm optimization (PSO), and ant colony optimization (ACO) with 80% of data from experiment utilized for the training and the remaining 20% for the validation. Finally, while testing, the error value is minimized and the performance obtained in the ACO for the parameters such as compressive strength, split tensile strength, flexural strength, and deflection is 91%, 98%, 87%, and 94% of predicted values, respectively, in the mathematical modeling. J. Rex and B. Kameshwari Copyright © 2016 J. Rex and B. Kameshwari. All rights reserved. Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition Thu, 04 Feb 2016 12:59:54 +0000 This paper presents a study of crystallographic evolution of disposed ark clam shell (ACS) after calcination at 400–1400°C which was kept at room temperature under ambient condition in Malaysia during nine months. A better understanding of hydration and recarbonation of ACS powder (≤63 μm) after calcination was discovered by PXRD and FTIR. The research focuses on the crystallographic transformation, biogenic calcite decomposition, and unusual atmospheric aragonite formation in ACS after calcination and atmospheric air exposure. Ex situ PXRD showed calcite present in ACS at ≤900°C. ACS transformed to pyrogenic fcc CaO at ≥800°C after three months. Long term atmospheric air exposure of decarbonized ACS caused nucleation of nonbiogenic aragonite, vaterite, calcite, and portlandite. However, in situ PXRD analysis of ACS at instantaneous temperature without cooling process does not indicate the presence of aragonite, vaterite, and portlandite crystals. FTIR spectra revealed CaO–CO2 bond in ACS dissociated with temperature (600–900°C) to form CaO and CO2. Ca–OH bond was also traced in FTIR spectra of ≥700°C. It resulted by hydroadsorption of CaO with H2O in atmospheric air. Chee Wah Loy, Khamirul Amin Matori, Way Foong Lim, Siegbert Schmid, Norhazlin Zainuddin, Zaidan Abdul Wahab, Zarifah Nadakkavil Alassan, and Mohd Hafiz Mohd Zaid Copyright © 2016 Chee Wah Loy et al. All rights reserved. The Integrated Fuzzy AHP and Goal Programing Model Based on LCA Results for Industrial Waste Management by Using the Nearest Weighted Approximation of FN: Aluminum Industry in Arak, Iran Wed, 03 Feb 2016 10:03:38 +0000 The worldwide recycled aluminum generation is increasing quickly thanks to the environmental considerations and continuous growing of use demands. Aluminum dross recycling, as the secondary aluminum process, has been always considered as a problematic issue in the world. The aim of this work is to propose a methodical and easy procedure for the proposed system selection as the MCDM problem. Here, an evaluation method, integrated FAHP, is presented to evaluate aluminum waste management systems. Therefore, we drive weights of each pair comparison matrix by the use of the goal programming (GP) model. The functional unit includes aluminum dross and aluminum scrap, which is defined as 1000 kilograms. The model is confirmed in the case of aluminum waste management in Arak. For the proposed integrated fuzzy AHP model, five alternatives are investigated. The results showed that, according to the selected attributes, the best waste management alternative is the one involving the primary aluminum ingot 99.5% including 200 kg and the secondary aluminum 98% (scrap) including 800 kg, and beneficiation activities are implemented, duplicate aluminum dross is recycled in the plant, and finally it is landfilled. Ramin Zare, Jafar Nouri, Mohammad Ali Abdoli, Farideh Atabi, and Majid Alavi Copyright © 2016 Ramin Zare et al. All rights reserved. Relationships among the Microstructure, Mechanical Properties, and Fatigue Behavior in Thin Ti6Al4V Tue, 02 Feb 2016 11:56:34 +0000 The microstructures of Ti6Al4V are complex and strongly affect its mechanical properties and fatigue behavior. This paper investigates the role of microstructure on mechanical and fatigue properties of thin-section Ti6Al4V sheets, with the aim of reviewing the effects of microstructure on fatigue properties where suboptimal microstructures might result following heat treatment of assemblies that may not be suited to further annealing, for example, following laser welding. Samples of Ti6Al4V sheet were subjected to a range of heat treatments, including annealing and water quenching from temperatures ranging from 650°C to 1050°C. Micrographs of these samples were inspected for microstructure, and hardness, 0.2% proof stress, elongation, and fracture strength were measured and attributed back to microstructure. Fractography was used to support the findings from microstructure and mechanical analyses. The strength ranking from high to low for the microstructures of thin Ti6Al4V sheets observed in this study is as follows: acicular martensite, Widmanstätten, bimodal, and equiaxed microstructure. The fatigue strength ranking from high to low is as follows: equiaxed, bimodal, Widmanstätten, and acicular martensite microstructure. Y. Fan, W. Tian, Y. Guo, Z. Sun, and J. Xu Copyright © 2016 Y. Fan et al. All rights reserved. Hydroxyapatite Whiskers Based Resin Composite versus Commercial Dental Composites: Mechanical and Biocompatibility Characterization Tue, 02 Feb 2016 07:09:47 +0000 A systematic evaluation of mechanical and biocompatibility properties of different volume fractions of hydroxyapatite whiskers in comparison with three commercial dental composites filled with micro- and nanosilica particles was carried out. Six groups with different hydroxyapatite whiskers mass fractions were taken into account in order to be compared with the performances of silica particles based composites group. Flexural properties were evaluated via a universal testing machine (2.5 kN Zwick Line) with a 2 kN load-cell (sensitivity 0.001 N). The test was replicated 10 times for the seven experimental groups to better identify statically the significance of the mechanical performances data. MTT quantitative colorimetric assay was performed in order to evaluate the mitochondrial activity of living cells exposed to different resin composites. Data obtained show better interfacial interaction with filler/matrix until 20 wt% of hydroxyapatite whiskers partially replaced silica particles filler. After this threshold, the mechanical performances decrease dramatically due to both the hydroxyapatite agglomerates formation and the low degree of resin conversion. In addition, biocompatibility test showed less cytotoxic effect with the addition of 20 wt% of hydroxyapatite in comparison with higher rates. L. Calabrese, F. Fabiano, M. Currò, C. Borsellino, L. M. Bonaccorsi, V. Fabiano, R. Ientile, and E. Proverbio Copyright © 2016 L. Calabrese et al. All rights reserved. Investigation of Rheological Behavior of Low Pressure Injection Molded Stainless Steel Feedstocks Thu, 28 Jan 2016 14:16:45 +0000 The purpose of this research is to investigate the influence of different powder loadings of 316L stainless steel (SS) powders on rheological behavior of feedstocks required for low pressure powder injection molding (L-PIM) process. The main idea consists in development of various formulations by varying 316L SS powder contents in feedstocks and evaluating the temperature sensitivity of feedstock via flow behavior index and activation energy. For this purpose, the irregular shape, spherical shape, and combination of both shapes and sizes (bimodal approach) of 316L SS powders are compounded with wax based composite binder. Moreover, the influence of elemental nanosized boron (B) addition (up to 1.5 wt.%) on rheological properties of irregular shape 316L SS powders is also evaluated using capillary rheometer method. It is observed that rheological parameters for solid powder loading of powder gas atomized (PGA) and bimodal powder P25/75 316L SS underwent sudden change from PGA-69 vol.% to PGA-72 vol.% and P25/75-67 vol.% to P25/75 316L SS 70 vol.%, respectively. Thus it is concluded that PGA-69 vol.% and P25/75-67 vol.% are optimal powder solid loadings corresponding to the lowest values of activation energies. Muhammad Aslam, Faiz Ahmad, Puteri Sri Melor Binti Megat Yusoff, Khurram Altaf, Mohd Afian Omar, H. P. S. Abdul Khalil, and M. Rafi Raza Copyright © 2016 Muhammad Aslam et al. All rights reserved. A Modified Method for Hardness Determination from Nanoindentation Experiments with Imperfect Indenters Wed, 27 Jan 2016 07:01:42 +0000 Nanoindentation is an effective nondestructive method for small scale determination of mechanical properties of materials. However, indentation response of metallic materials is very sensitive to indenter tip roundness, size effects, loading rate, and so forth. This study will analyze the effect of indenter shape imperfections on hardness determination. For this purpose, experimental investigations and finite element simulations are carried out. At first, it is found that hardness values determined with Oliver and Pharr’s method are affected by errors caused by imperfect indenter tip: errors increase for imperfect indenters with larger tip radii. Afterwards, several commonly used methods accounting at different extents for tip radius variations are compared. However, most of those methods are found not to be accurate for shallow indentation. For this reason, a novel hardness determination method based on geometrical relations of the imperfect indenter tip is developed. Results show that the new approach is very effective even in the case of shallow indentation. Wei Chao Guo, Heng Xu, Xin Qin Gao, Xiao Li Hou, and Yan Li Copyright © 2016 Wei Chao Guo et al. All rights reserved. Dynamic Wetting Behavior of Vibrated Droplets on a Micropillared Surface Tue, 26 Jan 2016 11:26:30 +0000 The dynamical wetting behavior has been observed under vertical vibration of a water droplet placed on a micropillared surface. The wetting transition takes place under the different processes. In compression process, the droplet is transited from Cassie state to Wenzel state. The droplet undergoes a Wenzel-Cassie wetting transition in restoring process and the droplet bounces off from the surface in bouncing process. Meanwhile, the wetting and dewetting models during vibration are proposed. The wetting transition is confirmed by the model calculation. This study has potential to be used to control the wetting state. Zhi-hai Jia, Wei Lei, Hui-nan Yang, and Gang Wang Copyright © 2016 Zhi-hai Jia et al. All rights reserved. Experimental Research on the Thermal Performance of Composite PCM Hollow Block Walls and Validation of Phase Transition Heat Transfer Models Tue, 26 Jan 2016 09:35:37 +0000 A type of concrete hollow block with typical structure and a common phase change material (PCM) were adopted. The PCM was filled into the hollow blocks by which the multiform composite PCM hollow blocks were made. The temperature-changing hot chamber method was used to test the thermal performance of block walls. The enthalpy method and the effective heat capacity method were used to calculate the heat transfer process. The results of the two methods can both reach the reasonable agreement with the experimental data. The unsteady-state thermal performance of the PCM hollow block walls is markedly higher than that of the wall without PCM. Furthermore, if the temperature of the PCM in the wall does not exceed its phase transition temperature range, the PCM wall can reach high thermal performance. Yuan Zhang, Sunqi Zhuang, Qian Wang, and Jiapeng He Copyright © 2016 Yuan Zhang et al. All rights reserved. Evaluation of the Properties of Bituminous Concrete Prepared from Brick-Stone Mix Aggregate Sun, 24 Jan 2016 12:30:39 +0000 The paper describes an investigation into mechanical properties of brick-stone bituminous concrete mix. The effect of brick-stone mix on various mechanical properties of the bituminous concrete such as Marshall stability, flow, Marshall Quotient (stability to flow ratio), Indirect Tensile Strength, stripping, rutting, and fatigue life of bituminous concrete overlay has been evaluated. In this study over-burnt brick aggregate (OBBA) and stone aggregate (SA) have been mixed in different ratios (by weight) such as 20 : 80, 40 : 60, 60 : 40, and 80 : 20, respectively. The laboratory results indicate that bituminous concrete, prepared by 20% brick aggregate and 80% stone aggregate, gives the highest Marshall stability. This bituminous concrete mix shows considerable improvement in various mechanical properties of the mix as compared to the other mixes. Dipankar Sarkar, Manish Pal, Ashoke K. Sarkar, and Umesh Mishra Copyright © 2016 Dipankar Sarkar et al. All rights reserved. Preparation of Active Carbon by Additional Activation with Potassium Hydroxide and Characterization of Their Properties Sun, 24 Jan 2016 06:31:40 +0000 A commercially available activated carbon was used to prepare active carbon via reactivation with KOH at 750°C. Active carbon was obtained with 60.5% yield. The resulting active carbon showed a well-developed porous structure with specific surface area 2939 m2/g, total pore volume 1.488 cm3/g, and micropore volume 1.001 cm3/g. Process reactivation of carbon changes its particle size as well as density properties and increases by nearly twice the amounts of methane and carbon dioxide adsorbed under high pressure conditions. Such active carbon may be used to enrich methane or carbon dioxide by pressure swing adsorption technique. Other possible applications of reactivated carbon are storage of hydrogen and methane and sequestration of carbon dioxide. Bronislaw Buczek Copyright © 2016 Bronislaw Buczek. All rights reserved. Load Bearing and Deformation Characteristics of Granular Spoils under Unconfined Compressive Loading for Coal Mine Backfill Thu, 21 Jan 2016 14:26:43 +0000 The load bearing capacity and deformation response of granular spoils under uniaxial compression are numerically and experimentally investigated, aiming to shed light on the performance of back filled waste spoils while controlling ground subsidence after coal extraction. In numerical study, the particles are assembled in PFC commercial code in light of the digitized real shape of spoils with image technique, which is proved to be consistent with the physical test. The results from numerical and laboratory experiments showed that the complete compressive process of spoils tended to have spatial and temporal characteristics. The load-strain curves of investigated specimens could be divided into three stages (stage I, rearranging stage; stage II, breaking stage; stage III, consolidating stage) and three zones (I, rearranging zone; II, interlocking zone; III, consolidated zone) from outside to inside. During stage I, the load increasing rate of smaller spoils is relatively low, but it increases faster than larger ones in stages II and III. In addition, spoils with Talbot’s gradation are greater than single gradations. The magnitude of the density in consolidated zone is maximum, indicating that it is the main part holding the overlying strata weight. Guodong Li, Shugang Cao, Yong Li, and Zhenyu Zhang Copyright © 2016 Guodong Li et al. All rights reserved. High-Temperature Performance and Multiscale Damage Mechanisms of Hollow Cellulose Fiber-Reinforced Concrete Wed, 20 Jan 2016 13:22:18 +0000 Spalling resistance properties and their damage mechanisms under high temperatures are studied in hollow cellulose fiber-reinforced concrete (CFRC) used in tunnel structures. Measurements of mass loss, relative dynamic elastic modulus, compressive strength, and splitting tensile strength of CFRC held under high temperatures (300, 600, 800, and 1050°C) for periods of 2.5, 4, and 5.5 h were carried out. The damage mechanism was analyzed using scanning electron microscopy, mercury intrusion porosimetry, thermal analysis, and X-ray diffraction phase analysis. The results demonstrate that cellulose fiber can reduce the performance loss of concrete at high temperatures; the effect of holding time on the performance is more noticeable below 600°C. After exposure to high temperatures, the performance of ordinary concrete deteriorates faster and spalls at 700–800°C; in contrast, cellulose fiber melts at a higher temperature, leaving a series of channels in the matrix that facilitate the release of the steam pressure inside the CFRC. Hollow cellulose fibers can thereby slow the damage caused by internal stress and improve the spalling resistance of concrete under high temperatures. Liping Guo, Wenxiao Zhang, Wei Sun, Bo Chen, and Yafan Liu Copyright © 2016 Liping Guo et al. All rights reserved. Analytical Evaluation of Reinforced Concrete Pier and Cast-in-Steel-Shell Pile Connection Behavior considering Steel-Concrete Interface Wed, 20 Jan 2016 09:44:34 +0000 The seismic design of bridges may require a large-diameter deep pile foundation such as a cast-in-steel-shell (CISS) pile where a reinforced concrete (RC) member is cast in a steel casing. In practice, the steel casing is not considered in the structural design and the pile is assumed to be an RC member. It is partially attributed to the difficulties in evaluation of composite action of a CISS pile. However, by considering benefits provided by composite action of the infilled concrete and the steel casing, both the cost and size of CISS pile can be reduced. In this study, the structural behavior of the RC pier and the CISS pile connection is simulated by using an advanced 3D finite element (FE) method, where the interface between the steel and concrete is also modeled. Firstly, the FE model is verified. Then, the parametric study is conducted. The analysis results suggest that the embedment length and the friction coefficient between the steel casing and the infilled concrete affect the structural behavior of the RC pier. Finally, the minimum embedment length with reference to the AASHTO design guideline is suggested considering the composite action of the CISS pile. Jiho Moon, Dawn E. Lehman, Charles W. Roeder, Hak-Eun Lee, and Tae-Hyung Lee Copyright © 2016 Jiho Moon et al. All rights reserved. An Approach Based on the Exploratory Data Analysis to Relate the Wear Behavior with the Microstructure of Ductile Cast Irons Tue, 19 Jan 2016 15:25:38 +0000 The aim of this work is to propose a new methodology to relate Ductile Cast Irons (DCIs) wear behavior with the separation distances and sizes of the graphite nodules through an Exploratory Data Analysis (EDA). This methodology consists of morphological image processing tools (compacity and size distribution curves), an EDA performed by the use of box plots and an EDA-based section classifying algorithm. This algorithm classifies the microstructure of DCIs into classes and levels grouping different behaviors of the separation distances and sizes of graphite nodules. Finally, it was found, through a number of tribological tests, that the obtained classes and levels have a different wear behavior. The results achieved by this methodology were compared with those of traditional techniques used to characterize the microstructure of the material. Jesus A. Basurto-Hurtado, L. A. Morales-Hernández, Roque A. Osornio-Rios, and Aurelio Dominguez-Gonzalez Copyright © 2016 Jesus A. Basurto-Hurtado et al. All rights reserved. Experimental Tests and Analytical Modelling of a Scaled Isolated Structure on Sliding and Elastomeric Bearings Tue, 19 Jan 2016 15:06:10 +0000 The main purpose of this study, which was conducted within the framework of a DPC-ReLUIS research project, was to investigate the behaviour of a scaled isolated structure equipped with an in-parallel combination of steel-PTFE sliding bearings and elastomeric bearings (HDRBs). For this purpose, dynamic tests on shaking table were carried out at the Laboratory of the Department of Structures for Engineering and Architecture of the University of Naples Federico II, Italy. An available prototype steel framed structure was used as a superstructure. A further objective of this study was to evaluate the reliability of different analytical models of the isolation system, commonly used, in order to adequately simulate the dynamic response of the isolated structure. The effectiveness of the isolation system was evaluated comparing the experimental response of the isolated structure with the numerical response of the fixed-base structure. Fabio Mazza and Alfonso Vulcano Copyright © 2016 Fabio Mazza and Alfonso Vulcano. All rights reserved. Green Synthesis of Silver Nanoparticles Using Apple Extract and Its Antibacterial Properties Tue, 19 Jan 2016 14:13:35 +0000 Silver nanoparticles (AgNPs) were synthesized using apple extract as a reducing agent and aqueous silver nitrate as the precursor. The AgNPs formation was observed as a color change of the mixture from colorless to dark-brownish. The X-ray diffraction pattern confirmed the presence of only Ag crystallites, and the dynamic light scattering estimates the average sizes of the AgNPs to be 30.25 ± 5.26 nm. Furthermore, Fourier Transform Infrared as well as UV-vis spectroscopy identifies ethylene groups as the reducing agent and capping agent for the formation of the AgNPs. This green synthesis provides an economic, eco-friendly, and clean synthesis route to AgNPs. AgNPs in suspension showed activity against Gram-negative and Gram-positive bacteria with minimum bactericidal concentrations (MBCs) to be in the range from 125 μg/mL to 1000 μg/mL. Zainal Abidin Ali, Rosiyah Yahya, Shamala Devi Sekaran, and R. Puteh Copyright © 2016 Zainal Abidin Ali et al. All rights reserved. Cost Optimization of Mortars Containing Different Pigments and Their Freeze-Thaw Resistance Properties Tue, 19 Jan 2016 12:35:08 +0000 Nowadays, it is common to use colored concrete or mortar in prefabricated concrete and reinforced concrete construction elements. Within the scope of this study, colored mortars were obtained with the addition of brown, yellow, black, and red pigments into the white cement. Those mixtures are examined for their compressive strength, unit weight, water absorption, and freeze-thaw resistance. Subsequent to comparison of these properties, a cost optimization has been conducted in order to compare pigment costs. The outcomes showed that the pore structure in architectural mortar applications plays an important role in terms of durability. And cost optimization results show that light colored minerals can be used instead of white cements. Sadık Alper Yıldızel, Gökhan Kaplan, and Ali Uğur Öztürk Copyright © 2016 Sadık Alper Yıldızel et al. All rights reserved. Corrigendum to “Survival Analysis of Factors Influencing Cyclic Fatigue of Nickel-Titanium Endodontic Instruments” Tue, 19 Jan 2016 11:55:13 +0000 Eva Fišerová, Martina Chvosteková, Silvie Bělašková, Michal Bumbálek, and Zdeněk Joska Copyright © 2016 Eva Fišerová et al. All rights reserved. Application of Metamodels to Identification of Metallic Materials Models Tue, 19 Jan 2016 07:49:32 +0000 Improvement of the efficiency of the inverse analysis (IA) for various material tests was the objective of the paper. Flow stress models and microstructure evolution models of various complexity of mathematical formulation were considered. Different types of experiments were performed and the results were used for the identification of models. Sensitivity analysis was performed for all the models and the importance of parameters in these models was evaluated. Metamodels based on artificial neural network were proposed to simulate experiments in the inverse solution. Performed analysis has shown that significant decrease of the computing times could be achieved when metamodels substitute finite element model in the inverse analysis, which is the case in the identification of flow stress models. Application of metamodels gave good results for flow stress models based on closed form equations accounting for an influence of temperature, strain, and strain rate (4 coefficients) and additionally for softening due to recrystallization (5 coefficients) and for softening and saturation (7 coefficients). Good accuracy and high efficiency of the IA were confirmed. On the contrary, identification of microstructure evolution models, including phase transformation models, did not give noticeable reduction of the computing time. Maciej Pietrzyk, Jan Kusiak, Danuta Szeliga, Łukasz Rauch, Łukasz Sztangret, and Grzegorz Górecki Copyright © 2016 Maciej Pietrzyk et al. All rights reserved. Effects of Deposition Potentials on the Morphology and Structure of Iron-Based Films on Carbon Steel Substrate in an Alkaline Solution Mon, 18 Jan 2016 09:00:22 +0000 The purpose of this work is to investigate the effect of electrochemical deposition potential on the morphology and structure of iron-based films on the carbon steel in an alkaline Fe(III)-triethanolamine solution. The deposition potentials were controlled in the range from −1.05 to −1.23  for 1800 s at 80°C. Total amount of electric charge for electrodeposition process was increased with increasing deposition potential in negative direction. Pure magnetite films with a columnar and defect-free structure were deposited in the potential range from −1.05  to −1.11 . However, petal-like magnetite film containing ferrihydrite and iron was formed at −1.17 . At more negative potential of −1.23 , two distinct layers were observed: a porous outer layer containing ferrihydrite and goethite and a compact inner layer consisting of columnar metallic iron. In the potential range from −1.05 to −1.11 , the pure magnetite films gradually increased the thickness and decreased the surface roughness with an increase of the overpotential. The magnetite film deposited at −1.11  showed the most thick layer and smooth surface state. Soon-Hyeok Jeon, Geun-Dong Song, and Do Haeng Hur Copyright © 2016 Soon-Hyeok Jeon et al. All rights reserved. Modeling of Point Defects Annihilation in Multilayered Cu/Nb Composites under Irradiation Sun, 17 Jan 2016 13:57:50 +0000 This work focuses on a mathematical modeling of the response to irradiation of a multilayer composite material. Nonstationary balance equations are utilized to account for production, recombination, transport, and annihilation, or removal, of vacancies and interstitials at interfaces. Although the model developed has general validity, Cu/Nb multilayers are used as case study. Layer thickness, temperature, radiation intensity, and surface recombination coefficients were varied systematically to investigate their effect on point defect annihilation processes at interfaces. It is shown that point defect annihilation at interfaces mostly depends on point defect diffusion. The ability of interfaces to remove point defects can be described by a simple map constructed using only two dimensionless parameters, which provides a general tool to estimate the efficiency of vacancy and interstitial removal in multilayer composite materials. Sarah Fadda, Antonio Mario Locci, and Francesco Delogu Copyright © 2016 Sarah Fadda et al. All rights reserved. Torsional Behaviour and Finite Element Analysis of the Hybrid Laminated Composite Shafts: Comparison of VARTM with Vacuum Bagging Manufacturing Method Thu, 14 Jan 2016 10:27:22 +0000 Braided sleeve composite shafts are produced and their torsional behavior is investigated. The braided sleeves are slid over an Al tube to create very strong and rigid tubular form shafts and they are in the form of 2/2 twill biaxial fiber fabric that has been woven into a continuous sleeve. Carbon and glass fibers braided sleeves are used for the fabrication of the composite shafts. VARTM (vacuum assisted resin transfer molding) and Vacuum Bagging are the two different types of manufacturing methods used in the study. Torsional behaviors of the shafts are investigated experimentally in terms of fabrication methods and various composite materials parameters such as fiber types, layer thickness, and ply angles. Comparing the two methods in terms of the torque forces and strain angles, the shafts producing entirely carbon fiber show the highest torque capacities; however, considering the cost and performance criteria, the hybrid shaft made up of carbon and glass fibers is the optimum solution for average demanded properties. Additionally, FE (finite element) model of the shafts was created and analyzed by using ANSYS workbench environment. Results of finite element analysis are compared with the values of twisting angle and torque obtained by experimental tests. Mehmet Emin Taşdelen, Mehmet Halidun Keleştemur, and Ercan Şevkat Copyright © 2016 Mehmet Emin Taşdelen et al. All rights reserved. A Cell-Based Smoothed XFEM for Fracture in Piezoelectric Materials Wed, 13 Jan 2016 06:39:08 +0000 This paper presents a cell-based smoothed extended finite element method (CS-XFEM) to analyze fractures in piezoelectric materials. The method, which combines the cell-based smoothed finite element method (CS-FEM) and the extended finite element method (XFEM), shows advantages of both methods. The crack tip enrichment functions are specially derived to represent the characteristics of the displacement field and electric field around the crack tip in piezoelectric materials. With the help of the smoothing technique, integrating the singular derivatives of the crack tip enrichment functions is avoided by transforming interior integration into boundary integration. This is a significant advantage over XFEM. Numerical examples are presented to highlight the accuracy of the proposed CS-XFEM with the analytical solutions and the XFEM results. Li Ming Zhou, Guang Wei Meng, Feng Li, and Shuai Gu Copyright © 2016 Li Ming Zhou et al. All rights reserved. Atomic Force Microscopy of Structural-Mechanical Properties of Polyethylene Reinforced by Silicate Needle-Shaped Filler Mon, 11 Jan 2016 12:35:24 +0000 The paper presents the results of experimental studies of polyethylene-based composites reinforced with silicate needle-shaped filler (palygorskite) of different mass fraction (0, 5, 10, and 15%). These composites are less flammable and fire toxic than unfilled polyethylene. The structure (size, shape, and agglomeration of filler) and local mechanical properties of composites in nonstretched and elongated states were investigated by AFM. In stretched samples palygorskite takes a wavy shape, and at extremely high elongation the filler is orthogonal to the axis of tension. The smooth surfaces of the samples, required for AFM, were prepared using the heating/cooling procedure. Ilya A. Morozov, Oleg K. Garishin, Vladimir V. Shadrin, Victor A. Gerasin, and Maria A. Guseva Copyright © 2016 Ilya A. Morozov et al. All rights reserved. Experimental Study on the Tensile Property of a Novel Oriented Linear Porous Metal Mon, 11 Jan 2016 08:10:54 +0000 A novel oriented linear porous metal (OLPM) with high porosity was fabricated through solid-sintering method with cutting copper fibers. In this study, tensile experiments were conducted to investigate the fracture process of the OLPM and the effects of porosity and sintering parameters on the tensile properties. The typical tensile stress-strain plot of this material was obtained based on a large number of tensile test results. The plot can be divided into three stages, namely, initial linear elastic stage, plastic deformation stage, and tensile fracture stage. Based on the results, the fracture mechanism of the OLPM was further studied. Moreover, the porosity and sintering parameters were also varied to investigate their influence on the tensile properties. Tensile strength and plastic deformation were found to decrease with increasing porosity ranging from 70% to 90%. A higher sintering temperature produced a higher tensile strength for the OLPM sintered in the temperature range of 700°C–900°C, but the strength decreased at 1000°C. In addition, the extension of holding time could also slightly affect the tensile strength. Finally, the tensile properties of the OLPM are significantly higher than those of commercial porous metal and porous metal fiber sintered sheet. Bin Liu, Xin-gang Wang, Yong Tang, Wei Yuan, Chao-bin Fang, and Zhen-ping Wan Copyright © 2016 Bin Liu et al. All rights reserved. Prediction of Compressive Strength of Concrete Using Artificial Neural Network and Genetic Programming Sun, 10 Jan 2016 10:47:14 +0000 An effort has been made to develop concrete compressive strength prediction models with the help of two emerging data mining techniques, namely, Artificial Neural Networks (ANNs) and Genetic Programming (GP). The data for analysis and model development was collected at 28-, 56-, and 91-day curing periods through experiments conducted in the laboratory under standard controlled conditions. The developed models have also been tested on in situ concrete data taken from literature. A comparison of the prediction results obtained using both the models is presented and it can be inferred that the ANN model with the training function Levenberg-Marquardt (LM) for the prediction of concrete compressive strength is the best prediction tool. Palika Chopra, Rajendra Kumar Sharma, and Maneek Kumar Copyright © 2016 Palika Chopra et al. All rights reserved. Urea Formaldehyde Composites Reinforced with Sago Fibres Analysis by FTIR, TGA, and DSC Mon, 04 Jan 2016 14:01:04 +0000 Agricultural material or biomaterial plays an important role in the field of fibre-reinforced polymeric materials with their new range of applications and achieves the ecological objective. Composition and structure of the nature fibre and matrix must be taken into consideration for the end use. In this project, Sago fibre particleboard bonds with Urea Formaldehyde to form composite. Fourier Transform Infrared (FTIR) spectra are used to characterize the Sago/Urea Formaldehyde composite in terms of their functional group and bonding. Sago/UF composite with smaller particle and higher loading of fibre with 15 wt% of UF matrix has the higher curing properties. The composite will have a denser structure by adopting bigger particle and higher loading of UF matrix. The Sago/UF composite only endures a single stage of decomposition. Thermal stability results indicate that particle size, particle/matrix interface adhesion, and particle loading have great influence on the thermal properties of the composites. Tay Chen Chiang, Sinin Hamdan, and Mohd Shahril Osman Copyright © 2016 Tay Chen Chiang et al. All rights reserved. Adsorption of Saliva Related Protein on Denture Materials: An X-Ray Photoelectron Spectroscopy and Quartz Crystal Microbalance Study Mon, 04 Jan 2016 13:10:47 +0000 The aim of this study was to evaluate the difference in the adsorption behavior of different types of bovine salivary proteins on the PMMA and Ti QCM sensors are fabricated by spin-coating and sputtering onto bare QCM sensors by using QCM and X-ray photoelectron spectroscopy (XPS). SPM, XPS, and contact angle investigations were carried out to determine the chemical composition and surface wettability of the QCM surface. We discuss the quality of each sensor and evaluate the potential of the high-frequency QCM sensors by investigating the binding between the QCM sensor and the proteins albumin and mucin (a salivary-related protein). The SPM image showed a relatively homogeneous surface with nano-order roughness. The XPS survey spectra of the thin films coated on the sensors were similar to the binding energy of the characteristic spectra of PMMA and Ti. Additionally, the amount of salivary-related protein on the PMMA QCM sensor was higher than those on the Ti and Au QCM sensors. The difference of protein adsorption is proposed to be related to the wettability of each material. The PMMA and Ti QCM sensors are useful tools to study the adsorption and desorption of albumin and mucin on denture surfaces. Akiko Miyake, Satoshi Komasa, Yoshiya Hashimoto, Yutaka Komasa, and Joji Okazaki Copyright © 2016 Akiko Miyake et al. All rights reserved. Effects of Magnetite Aggregate and Steel Powder on Thermal Conductivity and Porosity in Concrete for Nuclear Power Plant Sun, 03 Jan 2016 13:23:26 +0000 Among many engineering advantages in concrete, low thermal conductivity is an attractive property. Concrete has been widely used for nuclear vessels and plant facilities for its excellent radiation shielding. The heat isolation through low thermal conductivity is actually positive for nuclear power plant concrete; however the property may cause adverse effect when fires and melt-down occur in nuclear vessel since cooling down from outer surface is almost impossible due to very low thermal conductivity. If concrete containing atomic reactor has higher thermal conductivity, the explosion risk of conductive may be partially reduced. This paper presents high thermally conductive concrete development. For the work, magnetite with varying replacements of normal aggregates and steel powder of 1.5% of volume are considered, and the equivalent thermal conductivity is evaluated. Only when the replacement ratio goes up to 30%, thermal conductivity increases rapidly to 2.5 times. Addition of steel powder is evaluated to be effective by 1.08~1.15 times. In order to evaluate the improvement of thermal conductivity, several models like ACI, DEMM, and MEM are studied, and their results are compared with test results. In the present work, the effects of steel powder and magnetite aggregate are studied not only for strength development but also for thermal behavior based on porosity. Han-Seung Lee and Seung-Jun Kwon Copyright © 2016 Han-Seung Lee and Seung-Jun Kwon. All rights reserved.