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Cervantes Vallejo, Francisco Javier - One of the best experts on this subject based on the ideXlab platform.
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Optimization of the heating system by electrical resistances in a rapid thermal response mold based on MSR-PSO-FEM
2019Co-Authors: Cervantes Vallejo, Francisco Javier, Gómez Karla, Soto Gerardo, Navarro Carolina, Mendoza HoracioAbstract:The aim of this work to optimization of the heating system by electrical resistances for a rapid thermal response mold (MRTR), using the response surface methodology (MSR). Applying the design technique of the Box-Behnken experiments, a matrix of experiments with four factors and three levels was designed. The design variables that are used to describe the design and shape of the heating system are the heat flux per unit area of the electrical resistance, the distances from the center of the heaters to the surface of the Cavity, the distance between the adjacent electrical resistors and the thickness of the heating plate. The heating time, the variation of the temperature in the Cavity and the Von-Mises stress were considered as the variables of the model. Thermal and thermal-structural resistance analyzes of the model based on finite element method (FEM) are performed to acquire the objective variables. Mathematical response surface models are developed using the mixed regression model and the response surface model and the variance analysis method (ANOVA) is used to verify the accuracy of these mathematical models. With the obtained models, the position of the electric resistances is optimized and the ratio between mass and volume of the Cavity Insert is reduced to minimize the heating time within a reasonable temperature distribution and structural strength, coupling the surface models of response developed with the method of particle swarm optimization (PSO). The results obtained indicate that the required heating time on the surface of the Cavity can be significantly reduced in the molding cycle, demonstrating with these the effectiveness of the heating system
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Optimization of the heating system by electrical resistances in a rapid thermal response mold based on MSR-PSO-FEM
Universitat Politècnica de Catalunya. CIMNE, 2019Co-Authors: Cervantes Vallejo, Francisco Javier, Camarillo Gómez, Karla Anhel, Pérez Soto, Gerardo Israel, Hernández Navarro Carolina, Orozco Mendoza HoracioAbstract:En el presente trabajo se presenta la optimización del sistema de calentamiento por resistencias eléctricas para un molde de respuesta térmica rápida (MRTR), usando la metodología de superficie de respuesta (MSR) así como una técnica de optimización. Aplicando la técnica de diseño de experimentos Box-Behnken, se diseñó una matriz de experimentos con cuatro factores y tres niveles. Las variables de diseño que se emplean para describir el diseño y la forma del sistema de calentamiento, son el flujo de calor por unidad de área de la resistencia eléctrica, las distancias desde el centro de los calentadores a la superficie de la cavidad, la distancia entre las resistencias eléctricas adyacentes y el espesor de la placa de calentamiento. El tiempo de calentamiento, la variación de la temperatura en la cavidad y los esfuerzos de Von-Mises fueron considerados como las variables del modelo. Se realizan análisis térmicos y de resistencia térmico-estructural del modelo basado en método de elemento finito (FEM por sus siglas en inglés) para adquirir las variables objetivas. Además, se desarrollan modelos matemáticos de superficie de respuesta mediante el modelo de regresión mixta y el modelo de superficie de respuesta y se emplea el método de análisis de varianza (ANOVA por sus siglas en inglés), para comprobar la exactitud de dichos modelos matemáticos. Con los modelos obtenidos, se optimiza la posición de las resistencias eléctricas y se reduce la relación entre masa y el volumen del Inserto de la cavidad para minimizar el tiempo de calentamiento dentro de una distribución de temperatura y resistencia estructural razonables, acoplando los modelos de superficie de respuesta desarrollados con el método de optimización de enjambre de partículas (PSO por sus siglas en inglés). Los resultados obtenidos muestran que el tiempo de calentamiento requerido en la superficie de la cavidad se puede reducir significativamente en el ciclo de moldeo, demostrando con estos la efectividad del sistema de calentamiento.The aim of this work to optimization of the heating system by electrical resistances for a rapid thermal response mold (MRTR), using the response surface methodology (MSR). Applying the design technique of the Box-Behnken experiments, a matrix of experiments with four factors and three levels was designed. The design variables that are used to describe the design and shape of the heating system are the heat flux per unit area of the electrical resistance, the distances from the center of the heaters to the surface of the Cavity, the distance between the adjacent electrical resistors and the thickness of the heating plate. The heating time, the variation of the temperature in the Cavity and the Von-Mises stress were considered as the variables of the model. Thermal and thermal-structural resistance analyzes of the model based on finite element method (FEM) are performed to acquire the objective variables. Mathematical response surface models are developed using the mixed regression model and the response surface model and the variance analysis method (ANOVA) is used to verify the accuracy of these mathematical models. With the obtained models, the position of the electric resistances is optimized and the ratio between mass and volume of the Cavity Insert is reduced to minimize the heating time within a reasonable temperature distribution and structural strength, coupling the surface models of response developed with the method of particle swarm optimization (PSO). The results obtained indicate that the required heating time on the surface of the Cavity can be significantly reduced in the molding cycle, demonstrating with these the effectiveness of the heating system.Peer Reviewe
Mendoza Horacio - One of the best experts on this subject based on the ideXlab platform.
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Optimization of the heating system by electrical resistances in a rapid thermal response mold based on MSR-PSO-FEM
2019Co-Authors: Cervantes Vallejo, Francisco Javier, Gómez Karla, Soto Gerardo, Navarro Carolina, Mendoza HoracioAbstract:The aim of this work to optimization of the heating system by electrical resistances for a rapid thermal response mold (MRTR), using the response surface methodology (MSR). Applying the design technique of the Box-Behnken experiments, a matrix of experiments with four factors and three levels was designed. The design variables that are used to describe the design and shape of the heating system are the heat flux per unit area of the electrical resistance, the distances from the center of the heaters to the surface of the Cavity, the distance between the adjacent electrical resistors and the thickness of the heating plate. The heating time, the variation of the temperature in the Cavity and the Von-Mises stress were considered as the variables of the model. Thermal and thermal-structural resistance analyzes of the model based on finite element method (FEM) are performed to acquire the objective variables. Mathematical response surface models are developed using the mixed regression model and the response surface model and the variance analysis method (ANOVA) is used to verify the accuracy of these mathematical models. With the obtained models, the position of the electric resistances is optimized and the ratio between mass and volume of the Cavity Insert is reduced to minimize the heating time within a reasonable temperature distribution and structural strength, coupling the surface models of response developed with the method of particle swarm optimization (PSO). The results obtained indicate that the required heating time on the surface of the Cavity can be significantly reduced in the molding cycle, demonstrating with these the effectiveness of the heating system
Jens Bergstrom - One of the best experts on this subject based on the ideXlab platform.
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simulation and evaluation of thermal fatigue cracking of hot work tool steels
International Journal of Fatigue, 2004Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Die casting is a very cost-efficient method of forming thin-walled and complex near net-shaped products with close geometric tolerances and good surface finish. A permanent die tool is used to make large quantities of identical products. The performance and tool life are limited by several mechanisms, e.g. thermal fatigue cracking, erosion, and corrosion. To develop new and more resistant tool materials for die casting detailed knowledge of the actual casting conditions and the tool failure mechanisms are essential. This thesis contributes to an increased knowledge of tool failure in die casting by investigating and simulating actual casting conditions and tool failure mechanisms.A method to record the temperature fluctuations in a Cavity Insert during actual brass die casting was developed, and details of the temperature conditions were obtained. Also, a test method based on cyclic induction heating and internal cooling of hollow cylindrical test rods was developed, where the surface strain during thermal cycling could be measured. This method reproduced the characteristic type of surface cracking observed on die casting tools, and proved to give information of the strains and stresses behind the fatigue failure.In actual die casting, the dominant tool failure mechanism is thermal fatigue cracking. The formation of the cracks is associated to accumulation of the local plastic strain that occurs during each casting cycle. Initial crack growth is facilitated by oxidation of the crack surfaces, and proceeded growth is facilitated by this oxidation in combination with crack filling of cast material, and by softening of the tool material. In addition, local enrichment of Pb at the crack front from the cast alloy melt was also observed to promote the crack growth in die casting of brass.In an investigation of thermal fatigue of two hot work tool steels, quenched and tempered to different conditions, it was found that low-cycle fatigue occurs, although the estimated tensile stress never exceed the initial yield strength of the steel. The reason is a gradual softening of the steel during the thermal cycling, and the presence of stress raising defects. The resistance against thermal cracking improves with initial tool steel hardness, because any initial ranking in hardness among the steels is unaffected by the thermal cycling.Another investigation on a selection of surface engineered tool steels, including common diffusion treatments, PVD coatings and combinations of these, showed that surface engineering generally reduce the resistance against thermal cracking as compared to untreated references, since the engineering processes influence negatively on the mechanical properties of the hot work tool steels.Finally, corrosion tests of CrN PVD-coated tool steels by exposing them to molten aluminium revealed the mechanisms of initiation and progress of liquid metal corrosion of this material combination, and that the corrosion resistance improves with the CrN coating thickness.
David D Thomas - One of the best experts on this subject based on the ideXlab platform.
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enhanced epr sensitivity from a ferroelectric Cavity Insert
Journal of Magnetic Resonance, 2001Co-Authors: Yuri E Nesmelov, Jack T Surek, David D ThomasAbstract:Abstract We report the development of a simple ferroelectric Cavity Insert that increases the electron paramagnetic resonance (EPR) sensitivity by an order of magnitude when a sample is placed within it. The Insert is a hollow cylinder (length 4.8 mm, outside diameter 1.7 mm, inside diameter 0.6 mm) made from a single crystal of KTaO 3 , which has a dielectric constant of 230 at X-band (9.5 GHz). Its outside dimensions were chosen to produce a resonant frequency in the X-band range, based on electromagnetic field modeling calculations. The Insert increases the microwave magnetic field ( H 1 ) at the center of the Insert by a factor of 7.4 when placed in an X-band TM 110 Cavity. This increases the EPR signal for a small (volume 0.13 μL) unsaturated nitroxide spin label sample by a factor of 64 at constant microwave power, and by a factor of 9.8 at constant H 1 . The Insert does not significantly affect the Cavity quality factor Q , indicating that this device simply redistributes the microwave fields within the Cavity, focusing H 1 onto the sample inside the Insert, thus increasing the filling factor. A similar signal enhancement is obtained in the TM 110 and TE 102 cavities, and when the Insert is oriented either vertically (parallel to the microwave field) or horizontally (parallel to the DC magnetic field) in the TM 110 Cavity. This order-of-magnitude sensitivity enhancement allows EPR spectroscopy to be performed in conventional high- Q cavities on small EPR samples previously only measurable in loop–gap or dielectric resonators. This is of particular importance for small samples of spin-labeled biomolecules.
Orozco Mendoza Horacio - One of the best experts on this subject based on the ideXlab platform.
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Optimization of the heating system by electrical resistances in a rapid thermal response mold based on MSR-PSO-FEM
Universitat Politècnica de Catalunya. CIMNE, 2019Co-Authors: Cervantes Vallejo, Francisco Javier, Camarillo Gómez, Karla Anhel, Pérez Soto, Gerardo Israel, Hernández Navarro Carolina, Orozco Mendoza HoracioAbstract:En el presente trabajo se presenta la optimización del sistema de calentamiento por resistencias eléctricas para un molde de respuesta térmica rápida (MRTR), usando la metodología de superficie de respuesta (MSR) así como una técnica de optimización. Aplicando la técnica de diseño de experimentos Box-Behnken, se diseñó una matriz de experimentos con cuatro factores y tres niveles. Las variables de diseño que se emplean para describir el diseño y la forma del sistema de calentamiento, son el flujo de calor por unidad de área de la resistencia eléctrica, las distancias desde el centro de los calentadores a la superficie de la cavidad, la distancia entre las resistencias eléctricas adyacentes y el espesor de la placa de calentamiento. El tiempo de calentamiento, la variación de la temperatura en la cavidad y los esfuerzos de Von-Mises fueron considerados como las variables del modelo. Se realizan análisis térmicos y de resistencia térmico-estructural del modelo basado en método de elemento finito (FEM por sus siglas en inglés) para adquirir las variables objetivas. Además, se desarrollan modelos matemáticos de superficie de respuesta mediante el modelo de regresión mixta y el modelo de superficie de respuesta y se emplea el método de análisis de varianza (ANOVA por sus siglas en inglés), para comprobar la exactitud de dichos modelos matemáticos. Con los modelos obtenidos, se optimiza la posición de las resistencias eléctricas y se reduce la relación entre masa y el volumen del Inserto de la cavidad para minimizar el tiempo de calentamiento dentro de una distribución de temperatura y resistencia estructural razonables, acoplando los modelos de superficie de respuesta desarrollados con el método de optimización de enjambre de partículas (PSO por sus siglas en inglés). Los resultados obtenidos muestran que el tiempo de calentamiento requerido en la superficie de la cavidad se puede reducir significativamente en el ciclo de moldeo, demostrando con estos la efectividad del sistema de calentamiento.The aim of this work to optimization of the heating system by electrical resistances for a rapid thermal response mold (MRTR), using the response surface methodology (MSR). Applying the design technique of the Box-Behnken experiments, a matrix of experiments with four factors and three levels was designed. The design variables that are used to describe the design and shape of the heating system are the heat flux per unit area of the electrical resistance, the distances from the center of the heaters to the surface of the Cavity, the distance between the adjacent electrical resistors and the thickness of the heating plate. The heating time, the variation of the temperature in the Cavity and the Von-Mises stress were considered as the variables of the model. Thermal and thermal-structural resistance analyzes of the model based on finite element method (FEM) are performed to acquire the objective variables. Mathematical response surface models are developed using the mixed regression model and the response surface model and the variance analysis method (ANOVA) is used to verify the accuracy of these mathematical models. With the obtained models, the position of the electric resistances is optimized and the ratio between mass and volume of the Cavity Insert is reduced to minimize the heating time within a reasonable temperature distribution and structural strength, coupling the surface models of response developed with the method of particle swarm optimization (PSO). The results obtained indicate that the required heating time on the surface of the Cavity can be significantly reduced in the molding cycle, demonstrating with these the effectiveness of the heating system.Peer Reviewe