The Experts below are selected from a list of 108 Experts worldwide ranked by ideXlab platform
P J Herrerafranco - One of the best experts on this subject based on the ideXlab platform.
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effect of fiber surface treatment on the fiber matrix bond strength of natural fiber reinforced composites
Composites Part B-engineering, 1999Co-Authors: A Valadezgonzalez, J M Cervantesuc, R Olayo, P J HerrerafrancoAbstract:Abstract The interfacial shear strength (IFSS) between natural fibers and a thermoplastic matrix has been improved by the morphological and silane chemical modification of the fiber surface. An alkaline treatment was used to enhance both the matrix fiber wetting and the chemical surface modification in order to improve the physicochemical interactions at the fiber–matrix interphase. For characterization of the mechanical properties of such interphase, a modification of the micromechanical techniques commonly used in the characterization of the IFSS for circular-cross-section smooth fibers is proposed. The relationships developed for circular fibers were modified to incorporate the natural fiber perimeter instead of an equivalent fiber diameter. From the micromechanical test's results it was found that both surface modifications, preimpregnation and chemical, improves the fiber–matrix IFSS. Finally, the results obtained from the single fiber fragmentation test seem to better agree with the effective mechanical properties measured for the Laminated Material than those obtained with the pull out test.
Dong Wei - One of the best experts on this subject based on the ideXlab platform.
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epoxy resin composition preparation method thereof Laminated Material and copper clad Laminated board manufactured by adopting epoxy resin composition
2012Co-Authors: Kehong Fang, Dong WeiAbstract:The invention relates to an epoxy resin composition, a preparation method thereof, a Laminated Material and a copper-clad Laminated board manufactured by adopting the epoxy resin composition. The epoxy resin composition comprises the following components in part by mass: 30 to 80 parts of epoxy resin, 20 to 50 parts of polyphenyl ether resin with a novel structure, 0 to 50 parts of filler and 1 to 20 parts of assistant, wherein the polyphenyl ether resin is obtained through redistribution reaction of polyphenyl ether and phenolic resin in the presence of a reaction initiator, and the number-average molecular weight of the polyphenyl ether resin is 1,000 to 5,000. The epoxy resin composition provided by the invention not only has good heat resistance and dielectric property, but also has simple and convenient preparation process and is favorable for industrialized large-scale production; and in addition, the Laminated Material and the copper-clad Laminated board manufactured by using the epoxy resin composition are applied to a printed circuit board, have good heat resistance, dielectric property and machining property, and are favorable for signal transmission of a high-frequency circuit board.
Fausto A Garcia - One of the best experts on this subject based on the ideXlab platform.
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study of dynamic behavior of a composite Laminated Material manufactured of the bark of lata s palm bactris guineensis
Composite Structures, 2018Co-Authors: A Pertuz, German Diaz, Daniel G Chavez, Fausto A GarciaAbstract:Abstract The use of alternative lignocellulosic raw Materials for development of new engineering composite Materials is researched. The study is based on the Lata’s palm “Bactris Guineensis” bark as the main constituent for glued Laminated composite Material manufacturing. Static mechanical properties as well as fatigue behaviors were studied, since in these types of loads a wide range of engineering dynamic applications can be envisaged. Tensile and hardness testing were performed for the characterization of static and mechanical properties. Additionally, fatigue testing was used to analyze the durability behavior of the composite Materials obtained and the fracture surface was analyzed by SEM microscopy. Vickers hardness and tensile resistance at the exterior bark demonstrated that it is the hardest and most resistant zone with 27,5 Vickers and 354 MPa values respectively. During fatigue testing, the temporary life zone was obtained from the stress vs. number of cycles curve (S vs Nf). The Basquin’s equation parameters were found ( S = A Â · N f b ), with: A = 321 MPa. and b = −0,060. Finally, in order to evaluate the potential use of glued Laminated Lata’s Palm as a composite Material constituent its mechanical characterization was performed.
Georges Marc - One of the best experts on this subject based on the ideXlab platform.
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Holographic Interferometry: From History to Modern Applications
2020Co-Authors: Georges MarcAbstract:In Chapter 6, Marc Georges presents the holographic interferometry technique. This technique allows the measurement of the phase of an object or a scene, which evolves over time, and is used to detect defects in Laminated Material. It can also be used for measuring the vibration modes of industrial components such as turbine blades. After defining the characteristics of an ideal system, Georges reviews the different implementations that have been proposed, moving from analog systems to the more modern electronic speckle pattern interferometry. Because the sensor resolution keeps improving, it is now possible to detect the interference fringes directly, which leads to the most recent digital holographic interferometry techniques, which are described at the end of the chapter.Peer reviewe
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Holographic Interferometry: From History to Modern Applications
'Elsevier BV', 2020Co-Authors: Georges MarcAbstract:peer reviewedaudience: researcher, professional, studentIn Chapter 6, Marc Georges presents the holographic interferometry technique. This technique allows the measurement of the phase of an object or a scene, which evolves over time, and is used to detect defects in Laminated Material. It can also be used for measuring the vibration modes of industrial components such as turbine blades. After defining the characteristics of an ideal system, Georges reviews the different implementations that have been proposed, moving from analog systems to the more modern electronic speckle pattern interferometry. Because the sensor resolution keeps improving, it is now possible to detect the interference fringes directly, which leads to the most recent digital holographic interferometry techniques, which are described at the end of the chapter
Marcelo Clécio Vargas Vega - One of the best experts on this subject based on the ideXlab platform.
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The influence of analysis of deformation by shear-equal channel angular extrusion and asimetric rolling on the mechanical properties of an aluminium AA1050
Universidade Federal de São Carlos, 2014Co-Authors: Marcelo Clécio Vargas VegaAbstract:Sabe-se que a estampabilidade em ligas de alumínio AA1050 não é favorecida quando as chapas são produzidas por laminação convencional devido ao surgimento de uma textura do tipo cubo {100} de forte intensidade após tratamentos térmicos de recristalização. O objetivo do trabalho foi investigar se processos com componentes de cisalhamento podem melhorar esta propriedade. Para este trabalho foram selecionados dois processos de deformação plástica que introduzem tensões de cisalhamento: Extrusão em canal angular (ECA) e Laminação assimétrica (LA); esses processos foram comparados à laminação convencional. Na laminação convencional a deformação resulta principalmente de esforços de compressão. No processo ECA o cisalhamento é imposto na intersecção de dois canais de mesma geometria que se interceptam formado um ângulo . Na laminação assimétrica o esforço de cisalhamento é introduzido devido à variação de velocidade entre os cilindros de laminação. Partiu-se de chapas de alumínio AA1050 produzidas pelo processo Caster. As deformações foram executadas basicamente em 4 esquemas: i) Laminação convencional com 70% de redução; ii) ECA rota A de 1 a 8 passes; iii) ECA rota A de 1 a 4 passes seguido por laminação convencional com redução de 70% e iv) LA com reduções variando de 30 a 50%. Foi realizada a caracterização mecânica e microestrutural do estado deformado e foi estudada a conformabilidade após tratamento térmico de recozimento. Na deformação por ECA foi observado a redução do tamanho de grão, que medido por EBSD e por microscopia eletrônica de transmissão foi de cerca de 1 μm. A evolução da deformação equivalente comparada com o aumento da dureza indicou uma estabilização do tamanho de grão/célula a partir de 4 passes. Após 8 passes a fração de contornos de alto ângulo ultrapassou a de contornos de baixo ângulo, ou seja, ocorreu recristalização dinâmica durante a deformação. A textura após um passe de ECA se aproximou da textura ideal para matriz ECA de 120. Mas para deformações com quatro e oito passes, a textura evoluiu para uma dispersão das orientações contendo os {111} paralelos à superfície da chapa (fibra ), o aparecimento de orientações do tipo cubo rodado (100) e de Goss rodado {110} . A laminação convencional após ECA provocou o retorno às orientações típicas de laminação: latão, cobre e Goss. A deformação por laminação assimétrica com uma diferença de velocidade tangencial de 1,2 impôs esforços de cisalhamento, porém foi necessário diminuir a redução por passes de 10% para 5% para que o cisalhamento adicional modificasse sensivelmente a textura. Comparando a estampabilidade dos materiais deformados, observou-se que a deformação ECA aumentou a profundidade da penetração no ensaio Erichsen, enquanto que a laminação diminuiu o índice Erichsen. A laminação assimétrica reduziu a intensidade de textura e destruiu a simetria das orientações cristalográficas. Esta amostra encruada apresentou estampabilidade superior à das amostras laminadas. Após o recozimento, as amostras de laminação convencional, com ou sem pré-deformação ECA apresentaram texturas típicas de Material laminado recozido com alto índice de textura tipo cubo. Nas amostras ECA a fibra não ficou estável e teve sua intensidade reduzida. Embora a intensidade de textura total tenha permanecido baixa, o aumento de deformação ECA antes do tratamento térmico reforçou a orientação Goss {110}. Já a amostra de laminação assimétrica houve dispersão das orientações na fibra //ND e tanto orientações cubo como cubo rodado estavam presentes. O menor índice de anisotropia planar foi obtido na amostra de 4 passes ECA recozida (representando uma menor tendência ao orelhamento) e um índice de penetração no ensaio Erichsen da mesma ordem de chapas laminadas convencionalmente. Demostrou-se que tanto a deformação ECA quanto a laminação assimétrica podem modificar significantemente a textura de deformação e de recozimento e melhorar as características de conformabilidade da liga de alumínio 1050. Esta etapa de processamento deve estar localizada no final do processo de conformação mecânica, antes do recozimento final.It is known that the formability of aluminum alloy AA1050 is not favored when sheets are produced by conventional rolling due to the appearance of intense cube texture {100} after recrystallization heat treatment. The objective of this study was to investigate whether components of shear processes can improve this property. For this work two processes of plastic deformation introducing shear stresses were selected: Equal channel angular extrusion (ECAE) and asymmetric rolling; these processes were compared to conventional rolling. In conventional rolling deformation results mainly compressive stresses. In the ECAE process shear is induced in the intersection of two channels of the same geometry that intersect by an angle In the asymmetric rolling the shear stress is basically increased due to the speed variation between the rolls. An AA1050 aluminum sheet produced by the twin roll casting process was used in this study. The deformations were performed basically in 4 paths: i) conventional rolling, 70% reduction, ii) ECAE 1-8 passes, iii) ECAE 1-4 passes followed by conventional rolling with reduction of 70% and iv) Asymetric Rolling with reductions 30-50%. The mechanical and microstructural characterization of the deformed state was performed and the formability after annealing heat treatment was studied. ECAE deformation reduced the grain size, which measured by EBSD and transmission electron microscopy yield 1 micrometer. The evolution of equivalent strain compared with the increase of the hardness indicated a grain size stabilization of the grain/cell after four ECAE extrusion passes. After 8 passes the fraction of high angle boundaries exceeded the low-angle boundaries, ie dynamic recrystallization occurred during deformation. The texture after one pass ECAE approached the ideal texture for a 120 ECAE die. For deformations with 4 - 8 ECAE passes, the texture evolved into scattering the orientations having the {111} plane parallel to the surface ( fiber), and into the formation of rotated cube {100} and rotated Goss {110} orientations. The conventional rolling after ECAE returned the orientations to typical rolling textures: brass, copper and Goss. Deformation by asymmetric rolling with a difference of tangential velocity of 1.2 imposed shear stress, but it was necessary to decrease the reduction rate from 10% to 5% per pass in order to appreciably modify the texture. Comparing the formability of the deformed Material, it was observed that ECAE increased the penetration depth in the Erichsen test, while rolling decreased the Erichsen index. Asymmetric rolling reduced the intensity of texture and destroyed the symmetry of the crystallographic orientations. The asymmetric rolled sample presented better formability than the rolled samples. After annealing, the samples of conventional rolling, with or without ECAE pre - strain, showed typical textures of annealed Laminated Material with high cube texture type. The fiber was not stable in the ECAE annealed samples. Although the overall texture intensity remained low, increasing ECAE deformation before heat treatment strengthened the Goss {110} orientation. For the asymmetric rolling the fiber orientations // ND was scattered and both rotated cube and cube orientations were present. The lowest index of planar anisotropy was obtained in the sample annealed after four ECAE passes, representing a lower tendency to fail, This sample also presented an index of penetration in Erichsen testing of the same order of conventionally rolled sheets. It has been shown that both ECA as the asymmetric rolling deformation can significantly modify the texture of deformation and annealing, and improve the characteristics of formability of aluminum alloy 1050. This processing step should be located at the end of mechanical forming process before final annealing
