bluuebunny/crossref_metadata_2025 huggingface dataset:
Durability of Earth Stabilized Material
Authors: Bahar Ramdane , Benazzoug Mouloud , Kenai Said
Published: March 2014

This paper presents the results of an experimental study on the durability of stabilized soil. The effect of the addition of chemical stabilizers such as cement, lime, filler and their combination on the durability of clay was examined. The durability of stabilized material was evaluated by conducting series of cyclic wetting-drying and weight loss tests. The study shows that the durability of earth material can be improved by cement and lime stabilizers. These stabilizers provide interesting properties of clays and the durability of stabilized material is greatly enhanced by a combination of these stabilizers.
Structural Integrity Assessment of Precast Concrete Slabs Employing Conventional and Recycled Coarse Aggregates via Vibration Tests
Authors: Pimentel Roberto Leal , Torres Sandro Marden , Ferreira Enildo Tales , de Melo Aluísio Braz
Published: March 2014

Precast slabs were tested, consisting of ceramic blocks supported by concrete ribs and with a concrete topping a few centimeters thick. These structures are very common in Brazil, being employed for the construction of houses and small buildings. In one of the tested slabs, recycled coarse aggregate was employed while conventional aggregate (granite gravels and quartz sand) was employed in the other tested slab. This study is part of a broader experimental programme which was designed to assess the applicability of concrete containing recycled aggregates as conventional aggregate replacement. In order to get insight into the structural behavior of slabs with recycled aggregates, the main focus of this paper is to assess the effect of structural load level on vibration parameters (Resonance Frequency, Damping Ratio and Transit Time). Full scale slab structural integrity was assessed by following changes in these parameters via a vibration (modal) test employing impact excitation. The structures were tested for several static load ratios (load to ultimate loading ratios (55%, 82% and 98%)). Visual inspection of induced cracking was also performed. The results obtained indicate a reduction of stiffness in both slabs up to 50% of the stiffness of the respective uncracked structure, which followed a similar trend despite the aggregate types. As for the damping ratios, the recycled aggregate containing slab showed lower values in comparison to the control slab with conventional aggregate. Whereas the former results might indicate similar load capacity, the latter, in principle, may have implications for the vibration serviceability limit state of structures. However, although structures with lower damping ratio can potentially present vibration problems, these studied elements are not often subjected to excessive vibration in its service life.
Development and Experimental Analysis of Ceramic Bricks Panels for Structural Masonry Construction Systems
Authors: Delgado Luiz Roberto , Moita Gray Farias
Published: March 2014

The purpose of this work is to develop a modular construction system for housing using structural masonry. As part of the investigation, ceramic brick panels were fabricated and had their structural behavior under compression and bending experimentally evaluated. The connections between the panels were made longitudinally and in the corners, using grouted metallic clips. The panels connected by clips were submitted to impact tests to assess the effectiveness of these joints when subjected to conditions of use in houses. Additionally, the research took into consideration the constructive process of prefabricated buildings, regarding the transportation and assembly of ceramic panels, by means of qualitative analysis. Based upon the results, it could be concluded that the behavior of structural ceramic panels and their connections were suitable for use in houses. The possibility of their use in industrialized prefabricates was also observed. The study indicates some aspects that must be evaluated and improved to confirm the viability of using these ceramic panels in the manufacture of structural masonry housing units, thus becoming an important mechanism for reducing the housing deficit in Brazil.
Characterization of Physical, Mechanical and Fire Properties of Fiber Glass Composite due to Weight Fraction
Authors: Hasan Ebtisam H. , Helal Magdy A. , Nour Mohamed A. , Shokry Khaled M.
Published: March 2014

Glass-fiber reinforced plastics marketed are predominately based on one type of glass-fiber but with a wide variety of fiber formats, resin types, fillers and a wide range of process techniques. These choices result in materials with a wide range of behaviors in different applications. The aim of this work is to study the effect of different weight fraction for two types of polymeric composites for construction use. The properties of the two types of composites are characterized using conventional techniques.. The study revealed that weight fraction of 30 40 % for reinforcing glass fiber/polyester composite would achieve better characteristics. The addition of short fibers to a polymeric matrix will reduce its coefficient of thermal expansion.
Mechanical Behavior of Glued Laminated Pressed Bamboo Guadua Using Different Adhesives and Environmental Conditions
Authors: Luna Patricia , Takeuchi Caori , Cordón Edwar
Published: March 2014

This paper presents the mechanical properties measured on glued laminated pressed guadua samples. Experimental tests like shear parallel to fiber, tensile and shear perpendicular to fiber and flexural tests were carried out using three different types of adhesives: European Melamine Urea Formaldehyde, Colombian Melamine Urea Formaldehyde, and Polivinil Acetate humidity resistant. In order to study the behavior of the material in aggressive environmental conditions, half of the samples used in the mechanical tests were introduced in a temperature and humidity chamber for 45 days set to 45°C of temperature and 95% of relative humidity, usual environmental conditions in Chocó Colombia.The results showed that the highest values of mechanical strength were obtained for samples made with European Melamine Urea Formaldehyde. In addition, it was found that this adhesive was the one with better behavior under the aggressive environmental conditions simulated.
Experimental Study of Granular Rubber Waste Tire Reinforced Soil for Geotechnical Applications
Authors: Ramirez Gary G.D. , Casagrande Michéle D.T.
Published: March 2014

Large quantities of waste tires are released to the environment in an undesirable way. The amount of this scrap is increasing every year. The potential use of this waste material in geotechnical applications can contribute to reducing the tire disposal problem and to improve strength and deformation characteristics of soils. This paper presents a laboratory study on the effect of granular rubber waste tire on the physical properties of a clayey soil. Clayey soil was mixed with 10% of granular rubber by dry weight. Grain size, Atterberg limits analyses and compaction tests using standard effort were performed on the clayey soil. Consolidated-drained triaxial tests at confining stresses of 50, 100, 200 and 400 kPa were run on soil and mixture. The results conveyed that the geotechnical characteristics are influenced by the addition of grained tire, improving the cohesion and the angle of internal friction the clayey soil-granular rubber mixture. This improvement depends on the level of confining stress. The compaction test results indicated that the dry unit weights and the optimum moisture for the mixture decreased in relation to clayey soil. Therefore, this mixture can be used as lightweight fill material due to its low specific weight, solving low bearing capacity and high settlement problems of embankments on soft compressible soils.
Improvement of Residual Sugar Cane Bagasse Ash by Mechanical Grinding
Authors: Filho Primo Fernandes , Torres Sandro Marden , Perazzo Barbosa Normando , Vivian Maria de Arruda Magalhães , de Araújo Porto Vieira Andressa
Published: March 2014

This study investigated the effect of mechanical grinding of the residual sugar cane bagasse ash on its theoretical reactive capacity. The independent variables were: type of ball mill (rotary and centrifugal crusher), and milling time. The analyzed dependent variables were: specific surface, by Blaine equipment; and mineralogy, assessed by X-ray diffraction and infrared. The results indicate that the specific surface of the ball mill type centrifugal crusher was more efficient than the rotary, achieving an increase of 500% for an optimal grinding time of 60 min. The diffraction spectra X-ray and infrared were not altered due to the grinding process. Despite the degree of finess increase, it can be concluded that the used milling conditions were not able to modify their mineralogical characteristics. Both refinement processes were capable of enhancing the material reactivity while provided a significant increase in its specific surface. Longer milling times becomes unnecessary, because would cause little change in size distribution curve, at a high energy cost.
An Opportunity for Environmental Conservation: Evaluation of Test Material for Construction of Artificial Reefs Modules Trainers Made of Ecological Concrete
Authors: Bedoya Monica Andrea , Tobón Jorge Iván , Correa Herrera Tatiana , Correa Rendón Juan Diego
Published: March 2014

As a result of the degradation of coral reefs around the world and given that conservation efforts alone are not enough, artificial reefs have been proposed as a tool for the conservation of these ecosystems and recovery. As part of an initiative to develop modules forming artificial reefs made of concrete to promote the ecological conservation of the biodiversity of the Colombian Caribbean, this work constitutes a starting point. During eight months two trapezoidal plates were submerged in the waters surrounding the Bajo Grande (Isla Palma) archipelago de San Bernardo in the Colombian Caribbean; the plates were fabricated in concrete with Portland cement and waste ceramic. Seeking a more ecological product, aggregates were replaced entirely by ceramic waste. After making biological and physicochemical evaluations of the material exposed to the marine environment it was concluded that this is a favorable substrate for the development of coral reefs; and the plates were colonized on more than 30% of its surface by marine organisms, their structure was found internally stable and there were no adverse effects on marine biota near the test site.
Characterization of Ash Sludge from Wastewater Treatment Plants: Assessment for Construction Purposes
Authors: da Silveira Thiago Rosa Cristiane Maria , Melges José Luiz Pinheiro , Payá Jordi , Akasaki Jorge Luís , Marinho Jean Richard Dasnoy , Oliveira Douglas Santos
Published: March 2014

Considering that the human being is in a universe where the population demand for consumer goods is rapidly growing, the United Nations (UN) concluded that the effective implementation of the use of renewable resources has a nearing deadline. As a result of population growth, a massive waste is generated, especially sewage, requiring adjustments in its disposal, treatment and final disposal. Based on this information, it must be highlighted that the generation of municipal waste due to the sewer, with a significant production of biogas and of sludge, presents major environmental problem due to their volume, size and features. This work points out that the ash of the wastewater sludge can have a more productive destination if used as an alternative material of construction. The research was divided into three stages. In the first stage, it was sample preparation sludge performed; in the second one, burning procedures were designed, and, in the third one, physical-chemical and mineralogical tests for the sewage sludge ash were made, seeking to assess the feasibility of using this residue in mortar and in concrete. According to the conducted studies, it was observed that there is a potential pozzolanic reactivity when using this material as a mineral admixture for Portland cement replacement.
Cement Artifact Produced with the Construction and Demolition Waste-CDW
Authors: Santos Marina H.S. , Albuquerque Albéria C. , Costa Juzélia S.
Published: March 2014

The project aims to use waste generated in the building construction industry as aggregate for use in artificial artifact of cement, replacing natural aggregate. We investigated the development of mechanical strength of bricks made ​​from construction waste, compared to a reference sample without residue. In this investigation were used mechanical, physical and chemical tests contained in current technical standards. The results demonstrated the viability of this product for masonry sealing. The feasibility of the product, reducing the cost and environmental impact justifies the relevance of the project.
Particleboards with Agricultural Wastes: Sugar Cane Bagasse and Reforestation Wood
Authors: de Castro Junior Sergio Luis , Garzón Nubia , Williams Daniel , Guesso Flávio Luís , Savastano Junior Holmer , Rossignolo João Adriano , Fiorelli Juliano
Published: March 2014

In this paper, it was consider the study of the use of sugarcane bagasse and wood particles, residues from the agricultural and the furniture industry, in order to add value to such materials. To add value to these materials it will be utilized in the manufacturing of hybrid panels consisting of wood particles and sugarcane bagasse in certain proportions (20%, 40% and 60%). For the production it was used the bi-component polyurethane resin based on castor oil. Analysis of the products was established based on the physical-mechanical standard NBR 14.810:2006. The hybrid panels were analyzed according to the data obtained in relation to the American standard ANSI A208.1-1999, in order to determine the best treatment for the possible use as a lining in agricultural buildings. Moreover, the hybrid panels were contrasted with panels of other formulations, with similar density. It was evident that the treatment constituting of 40% of sugar cane bagasse and 60% of wood particles had the best physical-mechanical, and showed a potential for the use in non-structural applications.
New Approaches to Bond between Bamboo and Concrete
Authors: Azadeh Arash , Kazemi Hassan Haji
Published: March 2014

Increasing bond between bamboo and concrete is one of the important concerns in using bamboo as reinforcement. Concrete cover rupture and bond failure between bamboo and concrete could be considered as two important causes of element rupture.In this paper, bamboo corrugation as a new method has been proposed. Bamboo corrugation is suggested as a mechanism to interlock bamboo and concrete in order to assist the cohesion and skin friction and increase the total bond. Because of remarkable difference between steel shear strength and longitudinal shear strength of bamboo, the interlock mechanism is different. First, the relation between parameters like bamboo longitudinal shear strength, concrete shear strength and the kind of coating or treating of bamboo has been investigated. Then, the proper shape of bamboo corrugation (relation between size, depth and space between dents) will obtain. Using corrugated bamboo strip can improve bond between these two materials even if bamboo strips have not been treated.
Reuse of Waste Water-Based Paint
Authors: de Souza Tavares Elcio Correia , Barbosa Tassyla Talyne Nunes , Filho Jose Narbal de Oliveira , Meneses Carla Gracy Ribeiro
Published: March 2014

Brazil is among the five largest world paint producers. According to the Brazilian Association of paint manufacturers, this sector has achieved in 2011 revenues of US$ 3.90 billion and produced 1.359 billion liters of paint. Today, construction sector absorbs about 65% of solid paint in that country. However, all that industrial process increases levels of paint waste, which are so many times disposed without proper treatment producing environmental contamination. Such waste when improperly managed can seriously harm human health as well as the environment. So, currently industries are seeking to minimize the waste at source and reuse them. In the state of Rio Grande do Norte, faced with need to implement environmental guidelines and to reduce environmental impacts caused by waste originating from manufacturing process,. Water-based paint manufacturers use an effluent treatment system through settling tanks and filtration of waste. Such residues can be used utilized in soil-cement bricks making. In this work manufactured soil-cement bricks using water-based paint waste as a fine aggregator. Recycled bricks were characterized by a fine water absorption and compressive strength according ABNT requirements. Results have also shown that these bricks can be used in building industry as a brick sealer.
A Technological Analysis Applied to Existing Building Insulated with Straw
Authors: Bertorello Anna Rita
Published: March 2014

The current building culture requires a more careful and sensitive attention to environmental problems and the necessity to reduce the building energy requirement using sustainable products and solutions (eg. re-use of agricultural by-products). This research concerns the study of insulating existing buildings with straw (internal and external insulation) realized in Europe and in New Mexico. The case studies are analyzed with a technological point of view through the dissection of the insulation build-up to understand the construction phases during its insulation. The analysis of each case regards three building parts: the upper enclosure, the vertical enclosure and the attachment between the vertical enclosure and the ground. The application of this working method allows the analysis and understanding of how different elements are connected to each other, the possible finishing solutions and the relationship between the straw insulation and the existing building. This research analyzes different examples in order to develop a possible improved solution through the critical analysis of different construction methods used in the buildings. It is possible to achieve a classification methods of straw insulation found in the study cases and analyze every single part in the insulation system.
Blocks for Performance of Masonry Using PET Bottle Seal: Thermal, Acoustic, and Mechanical and Evaluation
Authors: Viegas Leila Soares , Bezerra Ulisses Targino , Barbosa Normando Perazzo
Published: March 2014

Recycling and reuse of materials is seen as the most evident solution for sustainable development. One aspect relevant to this development refers to integration of engineering to devise ways that enable the reuse of materials considered as waste, but with great potential of applicability in the building industry itself, through the generation of appropriate technologies and products that can be an alternative to social housing. So, this research aims to propose the use of PET bottles incorporated in blocks for the implementation of masonry that provides a thermal insulation in social housing. For the execution of the blocks, the PET bottles were inserted and centered in wooden molds easily made, which were subsequently filled with mortar. Three walls were executed in masonry with conventional ceramic brick, and three walls with blocks of PET for comparison of performance in thermal, acoustic, and mechanical behavior, varying the mix proportion of mortar. The thermal test consisted of preparing panels having a height of 1.20 m and a width of 1.00 m, instrumented with five thermo pair in both sides, measuring the temperatures at the surface of incidence of the heat source and on the opposite side. The acoustic performance test was done in two ways, a pure and a more complex method, using a reverberating chamber, always placing a sound source on one side and measuring the sound pressure after the wave crossed the walls already thermally tested. To obtain the mechanical performance, measurements, the same panels were tested with compression in a structures laboratory. The masonry made with PET blocks showed in thermal tests, performance similar behavior to those obtained in conventional masonry. In the acoustic tests, masonry blocks made with PET were superior to masonry with ceramic blocks. In tests concerning the mechanical performance, all three PET block walls reached greater tensile strength than those with ceramic bricks. Therefore the blocks with PET can be used as sealing bricks. Their manufacturing process is simple and could be applied for use with poor populations with the support of an institution to produce that element of construction, generating employment and income.
Re-Start from Straw
Authors: Restagno Matteo , Ricci Gian Nicola , Bocco Guarneri Andrea
Published: March 2014

This paper describes the concept and realization of an earthquake-proof prototype to verify the appropriateness of an orphanage to be built in Haiti. The construction system utilizes mainly natural and local materials like rice straw bales and bamboo. This work is the result of a master thesis in Architecture at the Politecnico di Torino. It originates from the collaboration with Architettura senza frontiere Piemonte, an Italian NGO. The wider scope of the project is to contribute to returning to rice farming and to recognizing rice straw as an appropriate building material for Haiti. Both goals would constitute a step towards establishing an integrated social, economic, environmental, agricultural, and architectural process.
The Importance of Shear in the Deflection of Bamboo Beams
Authors: García-Aladín María Fernanda , García Humberto , Mosquera Juan Manuel , García José Jaime
Published: March 2014

According to the traditional theory of elasticity, the total deflection of a beam occurs due to the combined effect of both the bending moment and the shear force. In isotropic materials such as steel and concrete, the deflection due to shear is usually not taken into account since it represents only 1% of the total deformation approximately. However, in anisotropic materials such as bamboo, the deflection due to shear should be taken into account because it may represent more than 20% of the total deformation of the beam. To better predict the influence of the shear effect on the deflection of bamboo beams, the longitudinal Young ́s modulus and the shear modulus of Guadua angustifolia were determined through the application of repeated three-point bending tests of whole culms and small prismatic elements while aligning their length along the axial direction of the culm. In order to determine the value of the shear modulus, each test was carried out using four different spans. The end results for the culms were: the longitudinal modulus of elasticity E equal to 23525 MPa, and the shear modulus G equal to 298 MPa. Thus, the substantial difference between the Young ́s modulus and the shear modulus confirms the high anisotropy of bamboo, and results indicate that shear deformation should always be included for the calculation of deflections of bamboo structures. Furthermore, the significant differences between these values and those obtained with the small prismatic elements may be attributed to the anisotropy and heterogeneity of the material. However, more tests have to be accomplished to further corroborate these results and find other anisotropic elastic properties of the material.
Analysis of Wood Laminated Beams Reinforced with Sisal Fibres
Authors: Mascia Nilson Tadeu , Mayer Raul Martini , Moraes Reinaldo Washington
Published: March 2014

Natural fibres have recently raised attention for presenting adequate mechanical characteristics for the reinforcement of wood structural elements. The use of both natural fibres, in laminated beams and wood from reforestation, is in accordance with the current economic interest and sustainable appeal. This paper focuses on the analysis the viability of sisal fibre use, in wood laminated structures as a reinforcing material, taking three methods into consideration: Stress functions, Classical lamination theory and Transformed section method. The laminated beams were reinforced by sisal strips with a thickness of 2 mm and constituted by the species of wood: Pinus (Pinus sp). Each lamina has the following dimensions: width of 5 cm, height of 10 cm and length of 150 cm. It was noted that the differences between the results from the classical lamination theory and transformed section method were, in an average of 14 % and 16 % for normal and shear stresses respectively. The difference of 12 % for displacements is a normal result taking into account that the span used is considered high for this wood species. In relation to the stress function method, the differences are minimal, around less than 1% for all analyses. It was also noted that the beam with reinforcement presented a decrease of the values of normal and shear stresses and displacements in relation a beam without reinforcing fibres. This decrease was of the order of 8% for the normal and 5% for the shear stresses and 12 % for the displacements In general, the strengthening of wood laminated beams with sisal fibres is more effective for structures that are used only in wood structural elements, in which the elastic modulus is at least equal to these fibres.
Creep Behaviour of a Thermoresistant Steel Working under Thermal Loads
Authors: Hluscu Mihai , Tripa Pavel
Published: March 2014

The estimation of the lifetime for equipments and installations working at high temperatures represent an actual problem. In the last years, there have been proposed a lot of methods in order to evaluate the lifetime for the equipments working under creep conditions. In the frameworks of the paper, some results regarding the behavior of pipes belonging to a methane gas cracking reactor are presented. Pipes worked on about 160.000 hours under a pressure of 14 at and a temperature of 800°C. The behavior of the pipes under above mentioned pressure has been calculated and plotted. Creep tests were performed at 650 and 800°C, and on these bases was evaluated the creep strength of the material. With Larson-Miller method the results were prolonged for spans shorter than 10.000 hours. The creep strength variation curves, drawn for 1000 and 100000 hours can be used for predictions about the lifetime at different.
The Effect of the Secondary Bending Moment on the Fracture Strength Evaluation of the Laser Welded Joints from a Web Core Sandwich Structure
Authors: Cernescu Anghel , Romanoff Jani , Remes Heikki
Published: March 2014

During the last period the interest on the sandwich structures has became more favorable due to the strength to weight ratio. In the same manner, in ship building field the lightweight structures became more and more attractive. With increasing the usage fields has increased the need to study the behavior of these structures. In general all the sandwich structures loaded in bending shows an effect of the secondary bending moment. In the case of web core sandwich panels used in ship structures has been observed a pronounced effect of the secondary bending moment on laser welded joints. Considering this, the paper presents an analysis of the fracture strength of laser welded joints of a web core sandwich structure, due to the effect of secondary bending moment. In the first part, the paper analytical formulation of the secondary bending moments and their effect on welded joints. This effect is explained on the basis of angle α defined in the paper and which depends on the thickness of the face plate, the thickness of the web plate and respectively the height. The paper continues with a numerical analysis of the stress and strain state from a web core sandwich beam and where also it is analyzed the effect of the secondary bending moment on the fracture strength of laser welded joints. Based on the carried out study it was observed that for high thickness of the web plate the effect of secondary bending moments is the overloading of the welded joints, instead for small thickness of the web plate the effect of the secondary bending moments can be of the unloading the welded joints. However, a small thickness of the web plate can affect the rigidity of the structure. Therefore, based on this study was proposed a solution to reduce the secondary bending moment without reducing the stiffness of the sandwich panel. The analysis conducted in this paper can be a design criterion for the web core sandwich structures.
Considerations on the Necessity of Determining Principal Stresses and Directions for Analysis of Material Durability under Multiaxial Fatigue
Authors: Dumitru Ion , Kun Lorand , Sava Marcela , Hluscu Mihai
Published: March 2014

A special situation arises when multiaxial fatigue loadings are present, given not only the time-dependency of extreme principal stress values, but also the fact that principal plane positions change during one load cycle (non-proportional loading). Thus, the analysis of principal stress and principal direction variation becomes a very important step, necessary to be carried out before starting any multiaxial fatigue testing. Based on the above, the authors present a generalized method for computing principal stresses and determining principal plane positions, applicable for cyclic tension-torsion loadings with zero mean stresses but with different phase shifts and amplitude ratios. Based on original experimental data and data collected from the literature, the authors point out in the final part of the paper that the maximum principal shear stress can be considered as the main parameter for plotting Wöhler curves.
Troughing after Scarf Osteotomy Leads to Minimal Gait Alterations
Authors: Hărăgus Horia , Prejbeanu Radu , Vermesan Dinu , Bogdan Ciprian , Toth-Taşcău Mirela
Published: March 2014

We aimed to investigate whether troughing during scarf osteotomy for hallux valgus can be determined using plantar pressure analysis. In order to quantify the foot print area of a patient at 7 and 12 weeks after the surgery, the raw pressure data were exported to two matrixes. Each matrix has the size of the force distribution platform and contains the plantar force data of the patient in gait movement. These large matrixes containing both left and right pressure data were divided in small size matrixes and averaged. The computation was done in Matlab. The matrixes were flipped up in order to have the natural position of the footprint. The two were plotted as contours in Z axis but kept the external contours only. This difference was measured by subtracting the areas of the two contours. The results are typical footprints for left and right legs, at predetermined follow-up points.
Bending Performance of Concrete Beams Strengthened with Textile Reinforced Mortar TRM
Authors: Gil Lluis , Escrig Christian , Bernat-Maso Ernest
Published: March 2014

This work presents a method of strengthening concrete structures based on textiles of high strength and mortars. The combination of textiles and mortars produces a new composite material with cementitious matrix. This material can be used for the reinforcement of concrete beams under bending loads. We tested several combinations of fibers: glass, Poliparafenil Benzobisoxazol (PBO), steel and carbon fibers with mortar and we used them to reinforce precast concrete beams. All the specimens were tested with a four-point load test. We discuss the performance of the specimens and we compare the ultimate results with the formulae from FRP codes.
Calibration of a Wooden Floor Calculation Model Based on the Experimentally Determined Dynamic Characteristics
Authors: Gavriloaia Constantin , Corduban Calin , Isopescu Dorina , Ţăranu Nicolae , Budescu Mihai
Published: March 2014

This paper aims to investigate a methodology to determine the elastic parameters of a wood-steel composite floor using the dynamic characteristics determined experimentally. Analytical and experimental dynamic analyses of the wooden floor are performed and the results are presented. Test results showed that the natural frequency values coming from the experiments differ considerably from those coming from the analytical studies due to the material characteristic values taken into consideration. An automatic comparison of vibration mode shapes obtained by finite element analysis and experimentally is made in order to calibrate de FEM model. By calibrating the FEM model using results from the vibration modal identification, an assessment of the structural system parameters can be obtained. The automatic model updating procedure highlighted the real elasticity modulus of the wood used, identified by testing wood specimens.
Energy - Absorption and Efficiency Diagrams of Rigid PUR Foams
Authors: Linul Emanoil , Serban Dan Andrei , Voiconi Tudor , Marsavina Liviu , Sadowski Tomasz
Published: March 2014

Polyurethane (PUR) foam materials represent a class of materials widely used for impact protection and energy absorption. This paper presents a characterization of different rigid PUR foams under compressive impact loading by means of energy absorption and efficiency diagrams. Compressive properties were investigated on cubic specimens on the foams’ rise direction at room temperature with a loading rate of 3.09 m/s for three different closed-cell foams with densities of 100 kg/m3, 160 kg/m3 and 300 kg/m3 respectively. Experimental results show that the compression modulus, yield stress and plateau stress increase with density. Most of the energy is absorbed in the plateau region because of the cell deformation associated with this phenomenon, allowing greater absorption of impact energy at nearly constant load. Authors have found that both the energy absorption and efficiency diagrams are consistent and present similar results for studied foams.
Apparatus for Measuring Dynamic Bulk Compliance of Time-Dependant Materials
Authors: Oseli Alen , Emri Igor
Published: March 2014

This paper describes a novel apparatus for measuring dynamic bulk compliance B*(ω) of time-dependant materials. System can measure dynamic bulk compliance at room temperature, at pressures up to 100 ± 1,5 bar and frequencies from 100 Hz to 1000 Hz. Functionality of the apparatus is demonstrated by performing measurements of dynamic bulk compliance for two different materials, i.e., polyvinyl acetate (PVAc) and thermoplastic polyurethane (TPU). Measurements were conducted at room temperature, atmospheric pressure and frequencies from 100 Hz to 1000 Hz.
State of Stress Determination in a Water Drinker by Numerical and Experimental Methods
Authors: Cherecheș Ioan Aurel , Dudescu Cristian , Lakatos Gheorghe Daniel , Vidican Ioan , Bejan Mircea
Published: March 2014

This paper presents the evaluation of residual stresses and stresses induced by external loads in a water drinker by numerical and experimental methods. The part, used in animal husbandry, is made of grey cast iron (EN GJL 200).
Numerical simulations were based on the finite element method, using ANSYS Workbench software to determine the stresses produced by external loads and finite volume method, using NovaFlow software, to determine residual stresses. The results obtained by numerical methods, were validated by experimental methods. Applied experimental methods consist of electrical resistive strain gauge technique to determine the state of stress in various loading conditions and the blind hole method to determine residual stresses, respectively.
Estimation of Thermal Stress Intensity Factor in a Strip with Various Property Gradations Subjected to Thermal Shock
Authors: Sadowski Tomasz , Pietras Daniel , Ivanov Ivelin
Published: March 2014

A numerical procedure of assessment of Thermal Stress Intensity Factors (TSIFs) of an edge crack in a strip made of Functionally Graded Material (FGM) subjected to thermal cooling process was elaborated. In order to perform it own subroutines in ABAQUS code were created. The analyzed ZrO2+Ti6AlV material in the form of the FGM is applied as cylinder liners (Thermal Barrier Coatings TBC) of aircrafts engines and is subjected to extremely quick temperature changes during the engine work. Therefore estimation of the TSIF to determine fracture process in the ZrO2+Ti6AlV material is important for designing of the structural element thermal protection and further safety of aircrafts passengers.
A Strength Calculation of a Nozzle Using Comparative Methods
Authors: Vasilescu Serban , Ilinca Costin
Published: March 2014

The stresses and deflections developed due to all piping loads produce some significant deformation in the nozzles of the pressure vessels. In this paper a spherical pressure vessel with two cylindrical nozzles are analyzed. The stresses in the nozzles are evaluated using two comparative methods: one of them represents the classical way of using the superposition of the axial, bending and torsional loads; the other one is based on the requirements of the ASME Boiler and Pressure Vessel Cod, Section VIII, Division 2 and is developed by a FE analysis. In order to obtain the loads (forces and moments) at the end of the nozzle a specialized finite element program has been used. This program (Coade Caesar 5.30) allows studying the strength and flexibility behavior of the pipes that connect the analyzed nozzle with the rest of the plant. The results obtained are compared in order to find when the using of the classical methods of strength of materials can be used as conservative approaches. The finite element method is applied in order to check the most important load cases that appear during the interaction between pipes and shell. In this respect the sustained (proper gravity loads), expansion (thermal loads) and occasional (wind and seismic loads) are combined in order to check all the requirements of ASME. This study contains also the effect of the pressure trust and the influence of the real geometry of the junction (nozzle-shell) in the peaks of the stresses.
Photoluminescence and Physical Properties of the Nano-Zn2SiO4:Mn Phosphor Powder under the Nitrogen Atmosphere
Authors: Yang Fann Wei , Cheng Chien Min , Chen Kai Huang
Published: March 2014

The subject of this work was to study the photoluminescence characteristics of nanoZnO and SiO2powders into Zn2SiO4phosphor, and to achieve better control on grain size and grain shape than traditional powder. The manganese elements were used to replace Zn2SiO4defects and to achieve better control on grain size and grain shape than traditional powder. With different sintering atmosphere conditions, the effect of the photoluminescence intensity due to sintering temperature and the concentration of activator were be discussed by the X-Ray diffraction, SEM and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles.
Co-Precipitation Synthesis and Photoluminescence Properties of Ce3+ Activated Terbium Aluminum Garnet (Tb1-xCex)3Al5O12 (0≤x≤0.05) Yellow Phosphors
Authors: Bi Jun , Li Ji Guang , Guan Wei Ming , Chen Jia Lin , Sun Xun Dong
Published: March 2014

Ce3+activated terbium aluminum garnet ((Tb1-xCex)3Al5O12, 0≤x≤0.05) phosphors have been converted from their precursors synthesized via co-precipitation from mixed solutions of aluminum and rare earth nitrates with ammonium hydrogen carbonate (AHC) as the precipitant. Detailed characterizations of the precursors and the phosphor oxides were performed by the combined techniques of X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), differential scanning calorimetry/thermogravimetry (DSC/TG), and photoluminescence spectroscopy. The co-precipitated precursors possess a general composition of (NH4)x(Tb,Ce)3Al5(CO3)y(OH)z·nH2O, and the particles, having diameters of about 50nm, are well dispersed. Calcining the precursors at 1000°C for 4 h in the air and then reducing in a hydrogen atmosphere at 1000°C for 2 h yielded a phase pure garnet solid-solution of (Tb1-xCex)3Al5O12. The cubic lattice of garnet allows the Ce3+activators to reside at the dodecahedral interstitial sites. The resultant garnet phosphors with various Ce3+contents exhibit nearly identical positions of the PLE/PE bands, but significantly different intensities. Upon blue-light excitation at 470nm, the garnet phosphors exhibit broad band emissions peaking at 560nm. The garnet phosphors show a luminescence quenching concentration of 1.5at% for Ce3+.
Fabrication and Characterization of AgCoO2 Delafossite by Cation Exchange Process
Authors: Feng Xiu Li , Liu Xiao Jiang , Yuan Yong Qiang
Published: March 2014

A new method to synthesize AgCoO2 delafossite powder with AgNO3 and LiCoO2 by the cation exchange solid state reaction at an atmospheric press has been presented. The effect factors such as moral ratio Ag/Li, reaction time, reaction temperature on the production were discussed systematically and the optimized preparation conditions were obtained. The crystal structure of AgCoO2 from XRD is monoclinic. SEM images showed that AgCoO2 is sheet in shape,single particle size is about 100nm and many single particles swam to form irregular polygon agglomerates.
Dispersion Behavior of Silicon Carbide Whisker
Authors: Zhang Li Li , Chen Yu Hong , Qi Li Min
Published: March 2014

The dispersion stability of silicon carbide whisker (SiCw) which is by-product of SiC was researched using distilled water as dispersing medium, polyethylene imine (PEI), tetramethylammonium hydroxide (TMAH), poly(meth)acrylamide (PMAM) as the dispersants. The sedimentation and optical microscope technology are used to observe whisker dispersion ，FTIR and ZETA electric potential are used to explore its dispersion mechanism . The results show that the order of dispersion capacity of the dispersant was PEI> TMAH> PMAM.When 1.25vol% PEI was used as dispersant, SiCw can be dispersed homogeneously at pH=9 and 10, in the meanwhile, if TMAH was used, the added amount would be 0.75vol% in which the pH is in range of 11-12.
Preparation and Properties of Aluminum Silicate Fiber Mat Impregnated Silica Sol
Authors: Sun Hao Ran , Zhang Shi Chao , Deng Zhi Wei , Wang Guang Hai , Chen Yu Feng , Fang Kai
Published: March 2014

Aluminum silicate/SiO2 sol composites are prepared by aluminum silicate fiber mats impregnated with different amount of silica sol. The effect of different impregnation process on impregnation amount of composites are compared, Thermal insulation performance and compression strength of composites are tested in this paper. The results show that: Samples prepared by vacuum impregnation process can get its highest impregnant amount, compressive strength of composites could achieve 241KPa.Thermal insulation performance of composites would be a liitle worse than aluminum silicate fiber products
Effects of pH on Preparation and Properties of CaTi2O4(OH)2 by Hydrothermal Method
Authors: Dong Wei Xia , Zhao Gao Ling , Gu Xing Yong , Song Bin , Han Gao Rong
Published: March 2014

A novel CaTi2O4(OH)2nanosheet was synthesized using anhydrous calcium chloride, lithium chloride and butyl titanate as the basic raw material by a template-free and surfactant-free hydrothermal method. The crystal structure, morphology and element synthesis were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) equipped with an EDS system. Effects of pH on the structure, morphology and electrochemical properties were investigated. The results showed that when pH was 6.7, CaTi2O5phase was obtained. When pH was 8.3, pure CaTi2O4(OH)2nanosheets were obtained. Further increasing pH to 8.6, CaTi2O4(OH)2was obtained, however, and CaTiO3phase also appeared. When pH was 8.3, the rate capacity of CaTi2O4(OH)2nanosheets was further higher than those of the samples prepared for pH=6.7 and pH=8.6. It indicated that CaTi2O4(OH)2nanosheets were helpful for lithium insertion and de-intercalation. The sample synthesized at pH=8.3 showed the best electrochemical performances, with first discharge specific capacity of 177.9 mAh/g at 0.1C rate. The CaTi2O4(OH)2nanosheets might represent an opportunity for the applications in lithium ion battery.
New Low-Toxic PEG(200)DMA/AM Gel System for 3YSZ Gel-Casting
Authors: Wu Hai Yan , Lu Heng , Liao Zhi Jie , Xia Feng , Xiao Jian Zhong
Published: March 2014

Gel-casting is promising in fabricating uniform and complex-shaped ceramic body, but it is confined in industrial application for the neurotoxic acrylamid (AM) gel system. Ether-contained oligomer poly(ethylene glycol)(200) dimethacrylate (PEG(200)DMA) with methacrylate end-group on either side of the long chain can act as cross-linking agent in free radical polymerization to form branchy gel network structure, which improves the green body strength. In this study, low-toxic PEG(200)DMA was chosen as the main binder and crosslinker and small dosage AM was applied to adjust the viscosity of the ceramic slurry to gel-cast 3YSZ (PEG(200)DMA: AM = 4:1, mass ratio). Influence of monomer concentration, dispersant concentration and solid loading on the rheological behavior of the slurry and the flexural strength of the green body were investigated using aqueous PEG(200)DMA/AM gel system to gel-cast 3YSZ. The results show that the flexural strength of green bodies notably increases with the increasing of monomer concentration and reaches high up to 14.4 MPa when gel-cast 3YSZ ceramics using PEG(200)DMA/AM gel system with appropriate amount of PAA-NH4, monomer and solid loading. This gel system obviously reduces the toxicity of the conventional AM system and, at the same time, ensures high flexural strength of green bodies.
Effect of Different Fluxing Agents on Basic Performance of Quartz Porous Ceramics for Molten Salt Infiltrating Spontaneously
Authors: Liu Tao , Li Yue Ming , Xie Zhi Xiang , Wang Zhu Mei , Hong Yan
Published: March 2014

Using quartz, feldspar as raw material, charcoal as pore-forming agent, adding CaSO4, Na2CO3, kaolin, KCl, LiF and NaF as fluxing agent respectively, quartz micro-porous ceramic matrices were prepared for inorganic salt/ceramic composite phase change energy storage materials. The effect of different fluxing agents on basic performance of porous ceramics and infiltration process were researched. The research shows that NaF can improve the strength of porous ceramics as fluxing agent, and have little impact on high temperature mechanical strength of Na2SO4/SiO2phase change energy storage materials. When the mass ratio of quartz, feldspar and charcoal is 7:2:1 and NaF is 1 wt% of them, the quartz porous ceramics have good performance as follows: the apparent porosity is 53.74%, the bulk density is 1.19 g/cm3, the compressive strength is 10.1 MPa, the average pore size is 12.53 μm, molten salt infiltration rate is 50.02 %, and the molten salt leakage rate is only 0.42 ‰ after 20 times of thermal loops.
Solvothermal Synthesis and Characterization of Lithium Tantalate Nanoparticles
Authors: Gao Lin Qiang , Chen Hai Yan , Wang Zhen , Zou Xin
Published: March 2014

Nanoscale LiTaO3 powders with perovskite structure were synthesized using the solvothermal technique with glycol as solvent at 240°C for 12h. The powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD was used to elucidate room temperature structures using Rietveld refinement. The powders were pure single pervoskite phase with high crystallinity. FESEM and TEM were used to determine particle size and morphology. The average LiTaO3 grain size was estimated to be < 200nm, and TEM images indicated that LiTaO3 particles had a brick-like morphology. In addition, the effect of the temperature on the LiTaO3 power characterisitics was also detailed studied.