This study aimed at dissimilar metal butt friction stir welding in various types of processing conditions on the welding product hardness, tensile strength, etc. At first, using the AA-5052 as the similar material in FSW(friction stir welding) process. Compare the affected in different working parameter such like tool rotation speed, tool feed rate, etc. During FSW process, using the K-type thermal couple to monitoring the temperature history at different position in the specimen. According the result and finding the best working parameter. As the result shown, the high speed rotating rate or the low feeding rate will cause more heat energy in the specimen. In completed FSW condition, the range of rotating rate is 600-900rpm, the feeding rate is 40-80mm/min, the preheating temperature is suitable in 350¢J. For the aluminum alloy and copper alloy of the dissimilar metal friction stir welding, specimen¡¦s surface has holes and large chip by lacking heat during using the tool diameter of 12mm to weld, use the tool diameter of 15mm to weld can enhance the heat during the welding process and improve the production of surface.

O elevado fluxo de calor envolvido no processo de soldagem de componentes favorece o aparecimento de tensões residuais, cujo alívio propicia o surgimento das distorções. Uma vez que essas distorções podem comprometer a utilização dos componentes, tornam-se relevantes pesquisas a respeito dos parâmetros, mensuração e previsão das distorções. Este trabalho tem como objetivo analisar as distorções na soldagem GMAW de uma junta tipo T, através do estudo termoestrutural em um modelo numérico pelo método dos elementos finitos com validação experimental. Para isso, o trabalho foi dividido em duas etapas sequenciais, sendo a primeira destinada à validação do modelo numérico e a segunda à elaboração de casos numéricos para análise. O modelo numérico utiliza elementos finitos tridimensionais para a obtenção do campo de temperaturas e distorções. Para a aplicação do fluxo de calor à peça utilizou-se a equação de Goldak como modelo de aporte de calor na análise térmica transiente. A dependência da temperatura na variação das propriedades físicas e mecânicas dos materiais foi considerada. A parte experimental da primeira etapa permitiu definir duas velocidades de soldagem mantendo a mesma energia do processo, originando dois conjuntos de parâmetros denominados como principais e alternativos. Na segunda etapa foram analisados oito casos, definidos através da combinação de três variáveis: variação da velocidade, sequência de soldagem e tempo de resfriamento entre filetes. O campo de temperaturas transiente é verificado pela medição de temperaturas em oito pontos, enquanto o campo de distorções é verificado utilizando um sistema de medição por coordenadas. Dentre os casos analisados, a menor distorção foi observada no caso 6 (velocidade mais rápida, sequência “vai-volta” e com intervalo de resfriamento) onde a distorção máxima foi de 4,31 mm, enquanto a maior distorção foi apresentada pelo caso 4 (velocidade mais lenta, sequência “vai-vai” e com intervalo de resfriamento) com distorção máxima de 6,41 mm. / The high heat flow involved in the component’s welding process favors the appearance of residual stress, which alleviation provides the appearance of distortions. Once these distortions can impair the use of the components, become relevant searches about the parameters, measurement and prediction of distortions. This work aims to analyze the distortions in GMAW welding of a T-type joint, through thermo-structural study in a numerical model by finite element method with experimental validation. For this, the work was divided in two sequential stages, the first aimed to the numerical model’s validation and the second to the development of numerical cases to analysis. The numerical model uses three-dimensional finite elements for obtainment the temperature field and distortions. For the application of heat flow to the part was used the Goldak’s equation as a model of heat input in transient thermal analysis. The temperature dependence in the variation of physical and mechanical properties of the materials was considered. The experimental part of the first stage allowed to define two welding speeds while keeping the same process energy, originating two sets of parameters called principal and alternative. In the second stage, eight cases were analyzed, defined by the combination of three variables: speed variation, sequence of welding and cooling time between fillets. The transient temperature field is checked by measuring temperatures in eight points, while the distortion field is checked using a coordinate measuring system. Among all cases analyzed, the lowest distortion was observed in case 6 (fastest speed, "going-back" sequence and cooling interval) in which the maximum distortion was 4.31 mm, while the largest distortion was presented by the case 4 (slower speed, "go-go" sequence and cooling interval) with maximum distortion of 6.41 mm.

O elevado fluxo de calor envolvido no processo de soldagem de componentes favorece o aparecimento de tensões residuais, cujo alívio propicia o surgimento das distorções. Uma vez que essas distorções podem comprometer a utilização dos componentes, tornam-se relevantes pesquisas a respeito dos parâmetros, mensuração e previsão das distorções. Este trabalho tem como objetivo analisar as distorções na soldagem GMAW de uma junta tipo T, através do estudo termoestrutural em um modelo numérico pelo método dos elementos finitos com validação experimental. Para isso, o trabalho foi dividido em duas etapas sequenciais, sendo a primeira destinada à validação do modelo numérico e a segunda à elaboração de casos numéricos para análise. O modelo numérico utiliza elementos finitos tridimensionais para a obtenção do campo de temperaturas e distorções. Para a aplicação do fluxo de calor à peça utilizou-se a equação de Goldak como modelo de aporte de calor na análise térmica transiente. A dependência da temperatura na variação das propriedades físicas e mecânicas dos materiais foi considerada. A parte experimental da primeira etapa permitiu definir duas velocidades de soldagem mantendo a mesma energia do processo, originando dois conjuntos de parâmetros denominados como principais e alternativos. Na segunda etapa foram analisados oito casos, definidos através da combinação de três variáveis: variação da velocidade, sequência de soldagem e tempo de resfriamento entre filetes. O campo de temperaturas transiente é verificado pela medição de temperaturas em oito pontos, enquanto o campo de distorções é verificado utilizando um sistema de medição por coordenadas. Dentre os casos analisados, a menor distorção foi observada no caso 6 (velocidade mais rápida, sequência “vai-volta” e com intervalo de resfriamento) onde a distorção máxima foi de 4,31 mm, enquanto a maior distorção foi apresentada pelo caso 4 (velocidade mais lenta, sequência “vai-vai” e com intervalo de resfriamento) com distorção máxima de 6,41 mm. / The high heat flow involved in the component’s welding process favors the appearance of residual stress, which alleviation provides the appearance of distortions. Once these distortions can impair the use of the components, become relevant searches about the parameters, measurement and prediction of distortions. This work aims to analyze the distortions in GMAW welding of a T-type joint, through thermo-structural study in a numerical model by finite element method with experimental validation. For this, the work was divided in two sequential stages, the first aimed to the numerical model’s validation and the second to the development of numerical cases to analysis. The numerical model uses three-dimensional finite elements for obtainment the temperature field and distortions. For the application of heat flow to the part was used the Goldak’s equation as a model of heat input in transient thermal analysis. The temperature dependence in the variation of physical and mechanical properties of the materials was considered. The experimental part of the first stage allowed to define two welding speeds while keeping the same process energy, originating two sets of parameters called principal and alternative. In the second stage, eight cases were analyzed, defined by the combination of three variables: speed variation, sequence of welding and cooling time between fillets. The transient temperature field is checked by measuring temperatures in eight points, while the distortion field is checked using a coordinate measuring system. Among all cases analyzed, the lowest distortion was observed in case 6 (fastest speed, "going-back" sequence and cooling interval) in which the maximum distortion was 4.31 mm, while the largest distortion was presented by the case 4 (slower speed, "go-go" sequence and cooling interval) with maximum distortion of 6.41 mm.

O elevado fluxo de calor envolvido no processo de soldagem de componentes favorece o aparecimento de tensões residuais, cujo alívio propicia o surgimento das distorções. Uma vez que essas distorções podem comprometer a utilização dos componentes, tornam-se relevantes pesquisas a respeito dos parâmetros, mensuração e previsão das distorções. Este trabalho tem como objetivo analisar as distorções na soldagem GMAW de uma junta tipo T, através do estudo termoestrutural em um modelo numérico pelo método dos elementos finitos com validação experimental. Para isso, o trabalho foi dividido em duas etapas sequenciais, sendo a primeira destinada à validação do modelo numérico e a segunda à elaboração de casos numéricos para análise. O modelo numérico utiliza elementos finitos tridimensionais para a obtenção do campo de temperaturas e distorções. Para a aplicação do fluxo de calor à peça utilizou-se a equação de Goldak como modelo de aporte de calor na análise térmica transiente. A dependência da temperatura na variação das propriedades físicas e mecânicas dos materiais foi considerada. A parte experimental da primeira etapa permitiu definir duas velocidades de soldagem mantendo a mesma energia do processo, originando dois conjuntos de parâmetros denominados como principais e alternativos. Na segunda etapa foram analisados oito casos, definidos através da combinação de três variáveis: variação da velocidade, sequência de soldagem e tempo de resfriamento entre filetes. O campo de temperaturas transiente é verificado pela medição de temperaturas em oito pontos, enquanto o campo de distorções é verificado utilizando um sistema de medição por coordenadas. Dentre os casos analisados, a menor distorção foi observada no caso 6 (velocidade mais rápida, sequência “vai-volta” e com intervalo de resfriamento) onde a distorção máxima foi de 4,31 mm, enquanto a maior distorção foi apresentada pelo caso 4 (velocidade mais lenta, sequência “vai-vai” e com intervalo de resfriamento) com distorção máxima de 6,41 mm. / The high heat flow involved in the component’s welding process favors the appearance of residual stress, which alleviation provides the appearance of distortions. Once these distortions can impair the use of the components, become relevant searches about the parameters, measurement and prediction of distortions. This work aims to analyze the distortions in GMAW welding of a T-type joint, through thermo-structural study in a numerical model by finite element method with experimental validation. For this, the work was divided in two sequential stages, the first aimed to the numerical model’s validation and the second to the development of numerical cases to analysis. The numerical model uses three-dimensional finite elements for obtainment the temperature field and distortions. For the application of heat flow to the part was used the Goldak’s equation as a model of heat input in transient thermal analysis. The temperature dependence in the variation of physical and mechanical properties of the materials was considered. The experimental part of the first stage allowed to define two welding speeds while keeping the same process energy, originating two sets of parameters called principal and alternative. In the second stage, eight cases were analyzed, defined by the combination of three variables: speed variation, sequence of welding and cooling time between fillets. The transient temperature field is checked by measuring temperatures in eight points, while the distortion field is checked using a coordinate measuring system. Among all cases analyzed, the lowest distortion was observed in case 6 (fastest speed, "going-back" sequence and cooling interval) in which the maximum distortion was 4.31 mm, while the largest distortion was presented by the case 4 (slower speed, "go-go" sequence and cooling interval) with maximum distortion of 6.41 mm.

The Variscan orogeny occured during Devonian to Carboniferous convergence between peri- Gondwanan crustal segments and the northern European plate (Baltica). Due to the convergence, Bohemian Massif represents the easternmost and largest exposure in the European Variscan belt. In the southern part of the Bohemian Massif, the Moldanubian Zone consists of several crustal segments with different polyphase tectonometamorphic histories. Moldanubian Zone is considered to represent the Variscan orogenic root, being surrounded by rigid and less metamorphosed blocks to the NW and SE. Structurally highest unit of the Moldanubian Zone is the Gföhl Unit, which is built by heterogeneous assemblage of high-pressure crustal and upper-mantle rocks comprising granulites, peridotites, pyroxenites and eclogites exhumed during Variscan orogeny. The apatite samples studied in my diploma thesis come from different types of granulites from the Blanský les granulite massif (BLGM) located SW of the town of České Budějovice. BLGM is the largest granulite body of the southern Bohemian Massif, is an integral part of the Gföhl Unit. BLGM consists mainly of calc-alkaline high-pressure felsic garnet ± kyanite granulites, which enclose up to several kilometers long lenses of ultrabasic rocks, numerous boudins of mafic...

Utilizing Phase Change Materials (PCM) for Latent Thermal Energy Storage (LTES) applications have previously been extensively researched as a measure to reduce greenhouse gas emissions from energy consumption. In order to make use of the waste heat from industrial processes for LTES purposes, a new demand emerged for PCMs capable of phase change in mid-temperature ranges of 100 °C - 200 °C. This higher temperature requirement made most of the previously studied material inapplicable as they had much lower melting and solidification temperatures. With this in mind, a new generation of PCMs consisting of Sugar Alcohols (SA) has been proposed. Erythritol is seen as an especially promising SA with good thermophysical properties for LTES purposes. However, it has been shown to suffer from severe supercooling, which makes it unreliable in real applications. To eradicate this issue, two additives, Graphene Oxide (GO) and Polyvinylpyrrolidone (PVP) at varying mass fractions were mixed with pure erythritol to form a composite which was studied using the Temperature-history (T-history) method to determine its effectiveness in reducing supercooling. Results show that at its most effective mass fraction, GO reduces supercooling by 28 o C and a 31 o C reduction is seen by the addition of PVP. The impacts on the duration of crystallization was also documented and analyzed using the same method. It was observed that the duration of crystallization was increased with increasing mass fractions of the additives. Other important properties of the composites were also studied in order to determine the overall feasibility for industrial applications. It includes analysis of the storage capacity through latent heat, changes in viscosity along with impacts on thermal diffusivity of the composites. / Att använda fasändringsmaterial (PCM) för termisk energilagring i form av latent värme (LTES) har tidigare extensivt forskats och undersökts som en lösning för att minska utsläppen av växthusgaser från energiförbrukning. För att utnyttja spillvärme från industriella processer för LTES-ändamål uppstod en efterfrågan på PCM som ändrar fas i temperaturer mellan 100 °C - 200 °C. Detta krav på högre temperatur gjorde att de flesta av de tidigare aktuella materialen inte kunde tillämpas eftersom de hade mycket lägre smält- och kristalliseringstemperaturer. Med detta i åtanke har en ny generation av PCM bestående av sockeralkoholer (SA) föreslagits. Erytritol ses som ett särskilt lovande SA med goda egenskaper för LTES-ändamål. Den har dock visat sig drabbas av svår underkylning, vilket gör den opålitligt i verkliga tillämpningar. För att utrota detta problem blandades två tillsatser, Graphene Oxide (GO) och Polyvinylpyrrolidone (PVP) vid olika massfraktioner med ren erytritol för att bilda en komposit som studerades med metoden Temperature-history (T-history) för att bestämma dess effektivitet på att minska underkylningen. Resultaten visar att GO på sin mest effektiva massfraktion minskar underkylningen med 28 o C och tillsats av PVP lyckats minska den med som mest 31 o C. Påverkningarna på varaktighet av kristallisering dokumenterades och analyserades med samma metod. Det var observerad att varaktigheten av kristallisering ökades med ökande massfraktioner av tillsatserna. Även andra viktiga egenskaper hos kompositerna studerades för att avgöra rimligheten att använda dessa för industriella tillämpningar. Det inkluderar analys av lagringskapaciteten genom latent värme, förändringar i viskositet tillsammans med påverkan på kompositernas termiska diffusivitet.

Utilizing Phase Change Materials (PCM) for Latent Thermal Energy Storage (LTES) applications have previously been extensively researched as a measure to reduce greenhouse gas emissions from energy consumption. In order to make use of the waste heat from industrial processes for LTES purposes, a new demand emerged for PCMs capable of phase change in mid-temperature ranges of 100 °C - 200 °C. This higher temperature requirement made most of the previously studied material inapplicable as they had much lower melting and solidification temperatures. With this in mind, a new generation of PCMs consisting of Sugar Alcohols (SA) has been proposed. Erythritol is seen as an especially promising SA with good thermophysical properties for LTES purposes. However, it has been shown to suffer from severe supercooling, which makes it unreliable in real applications. To eradicate this issue, two additives, Graphene Oxide (GO) and Polyvinylpyrrolidone (PVP) at varying mass fractions were mixed with pure erythritol to form a composite which was studied using the Temperature-history (T-history) method to determine its effectiveness in reducing supercooling. Results show that at its most effective mass fraction, GO reduces supercooling by 28 oC and a 31 oC reduction is seen by the addition of PVP. The impacts on the duration of crystallization was also documented and analyzed using the same method. It was observed that the duration of crystallization was increased with increasing mass fractions of the additives. Other important properties of the composites were also studied in order to determine the overall feasibility for industrial applications. It includes analysis of the storage capacity through latent heat, changes in viscosity along with impacts on thermal diffusivity of the composites. / Att använda fasändringsmaterial (PCM) för termisk energilagring i form av latent värme (LTES) har tidigare extensivt forskats och undersökts som en lösning för att minska utsläppen av växthusgaser från energiförbrukning. För att utnyttja spillvärme från industriella processer för LTES-ändamål uppstod en efterfrågan på PCM som ändrar fas i temperaturer mellan 100 °C - 200 °C. Detta krav på högre temperatur gjorde att de flesta av de tidigare aktuella materialen inte kunde tillämpas eftersom de hade mycket lägre smält- och kristalliseringstemperaturer. Med detta i åtanke har en ny generation av PCM bestående av sockeralkoholer (SA) föreslagits. Erytritol ses som ett särskilt lovande SA med goda egenskaper för LTES-ändamål. Den har dock visat sig drabbas av svår underkylning, vilket gör den opålitligt i verkliga tillämpningar. För att utrota detta problem blandades två tillsatser, Graphene Oxide (GO) och Polyvinylpyrrolidone (PVP) vid olika massfraktioner med ren erytritol för att bilda en komposit som studerades med metoden Temperature-history (T-history) för att bestämma dess effektivitet på att minska underkylningen. Resultaten visar att GO på sin mest effektiva massfraktion minskar underkylningen med 28 oC och tillsats av PVP lyckats minska den med som mest 31 oC. Påverkningarna på varaktighet av kristallisering dokumenterades och analyserades med samma metod. Det var observerad att varaktigheten av kristallisering ökades med ökande massfraktioner av tillsatserna. Även andra viktiga egenskaper hos kompositerna studerades för att avgöra rimligheten att använda dessa för industriella tillämpningar. Det inkluderar analys av lagringskapaciteten genom latent värme, förändringar i viskositet tillsammans med påverkan på kompositernas termiska diffusivitet.