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Material Selection (material + selection)
Selected AbstractsMulti-Criteria Material Selection of Monolithic and Multi-Materials in Engineering DesignADVANCED ENGINEERING MATERIALS, Issue 1-2 2006P. Sirisalee Multi-materials are combinations of monolithic materials in a chosen configuration and scale. They can help populate the material property space and fill areas monolithic materials cannot reach. This paper presents a novel approach to compare the performance of monolithic materials and multi-materials in multi-criteria design problems, with the results being visualised through exchange constant charts. In this paper, a particular type of multi-materials, sandwich panels, is selected to demonstrate the approach. [source] Multi-Criteria Material Selection in Engineering Design,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2004P. Sirisalee Material selection in real-world problems normally entails considering several, usually conflicting, design criteria/objectives. Thus, a designer has to strike a balance between these objectives to find the best compromise solution for the particular application. A novel design support tool, the exchange constant chart, has been developed in order to assist designers selecting materials in such multi-criteria situations. Two case studies are presented to illustrate the use of this tool. [source] Materials Selection for Optimal Design of a Porous Radiant Burner for Environmentally Driven Requirements,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Jaona Randrianalisoa Combustion supports which optimize a porous radiant burner are identified using a material selection approach. The optimization requirements account for the environmental aspect such as lower pollution. It was shown that high porosity metallic materials such as FeCrAlY foam, is always preferable in terms of pollution. From the viewpoint of thermal efficiency, metallic foams are better at high in-flux while Mullite foam takes over at low in-flux. [source] Advanced Experimental and Simulation Approaches to Meet Reliability Challenges of New Electronics SystemsADVANCED ENGINEERING MATERIALS, Issue 4 2009Dietmar Vogel Abstract This paper focuses on some advanced aspects of physics of failure approaches. Tracing of failure modes under realistic loading is a key issue to separate relevant failure sites to be studied in more detail. In the past design of experiment (DoE) tools have been developed to handle this problem. They allow to optimize design and/or material selection with respect to different failure mechanisms and sites. The application of these methods is demonstrated by optimizations performed for fracture problems. Interface fracture has been chosen as one of the most important failure mechanisms. Finally, local stress and strain measurement tools developed over the past years are presented at the end of the paper. They are tools to validate simulation results and therefore the underlying mechanical modeling. Namely, local stress measurement tools under development are needed to make realistic assumptions of loading conditions and to provide residual stress data for FEA. [source] Strength estimation of ceramic,metal joints with various interlayer thicknessFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2003M. TAKAHASHI ABSTRACT Residual stresses generated by the mismatch of thermal expansion coefficients of ceramics and metals affect the strength of ceramic,metal joints. An interlayer metal can be inserted between the ceramic and metal in order to relax this stress. An analysis was carried out of the residual stresses produced during joint-cooling and in 4-point bending tests. The effects of interlayer thickness on ceramic,metal joint strength were then studied by considering a superimposed stress distribution of the residual stress and the bending stress. Finally, joint strength was estimated from fracture mechanics and strength probability analysis by considering the residual stress distribution, defect size and position of pre-existing defects in the ceramic parts. As a result of this study, we suggest an optimum material selection and interlayer thickness for ceramic,metal joint structures. This approach is generally suitable for the design of electrical and mechanical structures. [source] Soil parent materials and the pottery of Roman Galilee: A comparative studyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2002Moshe Wieder The paper presents a comparative micromorphological analysis of the range of soil materials used to make the pottery of the hilly Galilee during the Roman period, and the ceramic products made from these materials. The four soil units that served as raw material for most of the pottery made in this period and region are examined along with pottery derived from each of them. For each soil unit, the soil characteristics and processes are described, followed by a presentation of the micromorphological characteristics of the soil material and those of the pottery made from that material. The contribution of the aeolian dust component to the soil materials is discussed as well as the identification of the tempering materials (nonplastics or other soil materials) added to the pottery paste. The study demonstrates the close correlation in microfabric between the pottery and original soil materials, sheds light on the raw material selection and modification practices of the potters of Roman Galilee, and has significant implications for provenance studies, using chemical analysis, on the pottery of this period and region. © 2002 Wiley Periodicals, Inc. [source] Influence of novel cycle concepts on the high-temperature corrosion of power plantsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 5 2008Bettina BordenetArticle first published online: 29 MAY 200 Abstract The aim to reduce CO2 emissions has triggered the evaluation of new cycle concepts for power plants. CO2 -capture concepts are also evaluated to add on new and existing power plants. For combined cycle power plants (CCPP), different cycles are investigated such as integrated gasification (IGCC) or oxy-fuel firing. Besides the difference in combustion compared to a conventional CCPP, the environmental boundary conditions are changed and will affect the oxidation and corrosion life of the materials in the hot-gas path of the gas turbine and the heat-recovery steam generator. For the circulating fluidised bed power plants, the biomass co-firing and the oxy-fuel firing are also foreseen for CO2 -emission reduction. The fireside corrosion of the water walls will be influenced by these concepts and the changed fuel. The corrosion risk has been evaluated for two new power plant concepts: combined cycle with exhaust gas recirculation and pulverised coal-fired boiler with oxy-fuel firing. Based on this evaluation, the consequences for the testing conditions and the material selection have been discussed in detail. [source] Optimizing periodic inspections in chemical plants by corrosion monitoringMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2007M. Winkelmans An efficient industrial corrosion monitoring system would give information about the corrosion activity and corrosion damage of critical components within a chemical plant in real time. A research project to develop an industrial tool for the simultaneous monitoring of general and localized corrosion was initiated. General and localized corrosion can be monitored by combining several non-destructive techniques. An industrial probe for corrosion monitoring is an excellent tool for an intelligent material selection, to identify critical process conditions or to optimize the use of corrosion inhibitors. The highest added value of an industrial tool for corrosion monitoring is its capacity to optimize periodic inspections. [source] A systematic investigation on the influence of the chemical treatment of natural fibers on the properties of their polymer matrix compositesPOLYMER COMPOSITES, Issue 5 2004Jerico Biagiotti This paper reports a systematic study of the effects on composite properties of different chemical treatments on natural fibers. Both short flax fibers and flax cellulose pulp in a polypropylene matrix have been investigated. The influence of treatments on fiber properties was investigated by means of spectroscopic, thermal and mechanical tests. Moreover, the effects of fiber treatment on the crystallinity of the matrix were analyzed using differential scanning calorimetry and optical microscopy. The mechanical properties of the composites obtained were studied using tensile and bending tests. It is shown that most of the main properties of the composites can be improved by adequately treating the fibers. The results of this study provide a database mainly devoted to material selection for the automotive industry. This research has been performed as a part of the ECOFINA project in the framework of the 5th European Research Program of the European Community. Polym. Compos. 25:470,479, 2004. © 2004 Society of Plastics Engineers. [source] Impact behavior of a short glass fiber reinforced thermoplastic polyurethanePOLYMER COMPOSITES, Issue 3 2000J. Jancar The temperature dependence of critical strain energy release rate (Gc,) and standardized Charpy notched impact strength (CNIS) were measured for a thermoplastic polyurethane (TPUR) reinforced with 30 wt% of short glass fibers (SGF) over a temperature interval ranging from ,150°C 23°C (RT) at two strain rates, 70 and 150 s,1, respectively. Fractographic observation of fracture planes was used to qualitatively assess the fracture modes and mechanisms. Adhesion between the reinforcement and the matrix was excellent and the integrity of the fiber-matrix interfacial contact was relatively insensitive to exposure to hydrolysis during the immersion in boiling water for 100 hours. At temperatures above ,30°C, there was a large extent of plastic deformation in the vicinity of crack planes while at temperatures below ,50°C, the extent of plastic deformation was substantially reduced. This resulted in a change in the major energy dissipation mechanism and led to a decrease of both CNIS and Gc, values for SGF/TPUR composites. It was suggested that the plastic deformation of TPUR matrix in the immediate vicinity of glass fibers was the primary source of energy dissipation at temperatures above ,30°C, while the friction and fiber pull-out was the main dissipative process below ,50°C. Over the whole temperature interval investigated, greater Gc, values were obtained at higher strain rate of 150 s,1, without any significant change in the fractographic patterns observed on the fracture planes. The CNIS/Gc, ratio, used to assess suitability of CNIS for comparison of materials, changed with temperature substantially suggesting that the functional dependences of CNIS and Gc, on temperature differ substantially. Hence, CNIS data do not provide a reliable base for material selection and for design purposes in this case. [source] Mixed matrix membrane materials with glassy polymers.POLYMER ENGINEERING & SCIENCE, Issue 7 2002Part Mixed matrix materials comprising molecular sieve entities embedded in a polymer matrix can economically increase membrane permselectivity, thereby addressing a key challenge hindering the widespread use of membrane-based gas separations. Prior work has clarified the importance of proper selection of the dispersed sieve phase and the continuous matrix phase based on their intrinsic transport properties. Proper material selection for the two components, while necessary, is not sufficient since the interfacial contact zone appears to be equally important to achieve optimum transport properties. Specifically, it was found that chemical coupling of the sieve to the polymer can lead to better macroscopic adhesion but to even poorer transport properties than in the absence of the adhesion promoter. This counterintuitive behavior may be attributed to a nanometric region of disturbed packing at the polymer sieve interphase. The poor properties are believed to result from "leakage" of gas molecules along this nanometric interface. The Maxwell model was modified to take into account these complexities and to provide a first order quantification of the nanometric interphase. The analysis indicates that optimization of the transport properties of the interfacial region is key to the formation of ideal mixed matrix materials. This approach is used in the second part of this paper to form successful mixed matrix membrane materials. [source] Determination of Materials Selection Performance Indices Through the Combination of Numerical Modeling and Optimization MethodsADVANCED ENGINEERING MATERIALS, Issue 11 2009German Castillo After translation, the first stages traditionally involved in the materials selection are filtration and classification, which require formulation of criteria (constraints or objectives) deduced from information written in the set of material requirements. These criteria, which are representative of the behavior of the material and the studied structure, must be formulated analytically in order to be used during selection stage. However, for complex behavior, analytical processing of models is no longer possible and it can be replaced by a combination of numerical resolution methods and an optimization method which make it possible to obtain approximate formal expressions of the criteria. In this paper, a complete selection method is proposed. The method is applied to the constraints as well as the objectives, in order to carry out the filtration and classification stages at the same time. The study of the thermomechanical behavior of a machine tool frame has been used to demonstrate the validity of the proposed method. [source] The Critical Role of the Underlayer Material and Thickness in Growing Vertically Aligned Carbon Nanotubes and Nanofibers on Metallic Substrates by Chemical Vapor DepositionADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Gilbert D. Nessim Abstract Vertically aligned carbon nanotubes and nanofibers are grown on metallic Ta and Pd underlayers at temperatures below 500,°C. Controlling the size of the grains of the underlayer film is critical because this leads to a more uniform distribution of catalyst dots, which in turn results in vertical alignment of the carbon nanostructures. Rapid and limited heating and appropriate materials selection can also be used to limit catalyst/underlayer reactions that hinder or suppress carbon nanostructure growth or that lead to entangled growth. Control of catalyst reactivity with metallic underlayers is significant because growth on conductive substrates is notoriously difficult, but needed for many applications such as the use of carbon nanostructures in microelectronic circuits. [source] Electrical Response to Organic Vapor of Conductive Composites from Amorphous Polymer/Carbon Black Prepared by Polymerization FillingMACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2003Jun Rong Li Abstract In recent years, conductive polymer composites have found applications as gas sensors because of their sudden change in electric resistance of several orders of magnitude when the materials are exposed to certain solvent vapors. However, the composites having this function reported so far are mostly based on crystalline polymeric matrices, which factually sets a limit to materials selection. The present work prepares polystyrene/carbon black composites through polymerization filling and proves that the amorphous polymer composites can also serve as gas sensing materials. The composites' percolation threshold is much lower than that of the composites produced by dispersive mixing. In addition, high responsivity to some organic vapors coupled with sufficient reproducibility is acquired. The experimental data show that molecular weight and molecular weight distribution of the matrix polymer and conducting filler content exert great influence on the electrical response behavior of the composites. As a result, composites performance can be purposely tailored accordingly. Compared with the approaches of melt-blending and solution-blending, the current technique is characterized by many advantages, such as simplicity, low cost, and easy to be controlled. Effect of different organic solvent vapors on the electric resistance of PS/CB composites (CB content,=,10.35 vol.-%). [source] | ||||||||||||||||||||||