Curvas granulométricas de alimentação e produto em etapas de britagem permitem modelar e avaliar o desempenho dos equipamentos. Essa pesquisa foi baseada na determinação de curvas granulométricas tendo como ponto de partida estudos sobre conceitos de amostragem de Gy, Napier-Munn, Minnitt e Pittard, sendo que as amostragens para definição dessas curvas granulométricas utilizaram análises de imagens. A importância deste estudo está relacionada à necessidade de conhecer o minério que abastece a usina, pois nesse caso de estudo, com o aprofundamento da cava, este vem se tornando mais compacto e resistente. Um dos objetivos essenciais é utilizar a amostragem via análise de imagens como ferramenta para determinação da granulometria de ROM alimentado na britagem primária de uma planta e aplicar a técnica nas demais fases. Foram definidas duas metodologias, uma para amostragem do ROM encaminhado à britagem primária e outra para alimentação da britagem terciária. Inicialmente, na amostragem de ROM (itabiritos friáveis), foi identificada a bancada de trabalho para que uma carga desmontada (259t) fosse basculada. Houve segregação dos blocos maiores que 2,5cm para análise e mensuração por imagens e formação da pilha para quarteamento e peneiramento. Os dados foram tratados e analisados, gerando as curvas granulométricas. A metodologia para amostrar a granulometria da alimentação da britagem terciária (itabiritos friáveis e granulados) partiu da identificação do ponto de amostragem, seguida de filmagens e determinação das imagens a serem utilizadas, simulando um amostrador automático. Os dados foram analisados e tratados com auxílio estatístico para obtenção das curvas. As metodologias foram consideradas de grande valia pois forneceram dados de granulometria com reprodutibilidade, porém mostraram-se laboriosas. Com relação ao ROM, o protocolo amostral apresenta taxas de redução de massa elevadas. As curvas abrangem ampla faixa de tamanhos, indicando que, apesar das etapas de homogeneização e divisão, os erros de viés e precisão (relativa = ±1%) resultantes frente à massa do lote retrocalculado (259t) foram desprezíveis. Nas curvas de ROM, 65% do material está retido em APA, 4% está na faixa entre APA e APF e 5% está retido em 1m, mostrando que frente amostrada atende às especificações do equipamento. Com relação à britagem terciária, foram realizados dois testes. Cada imagem gerou uma curva e cada teste gerou quatro curvas que geraram uma curva média. A curva média foi comparada com a de projeto, sendo a curva de granulado a mais próxima. As maiores variações ocorreram nos maiores tamanhos, acima de 80mm para granulado e de 50mm para friável. Também, foi observada a mesma quantidade de material entre APA e APF, porém 100% do material granulado alimentado nesta etapa estava retido em APF, indicando impactos nesta operação. As análises das curvas permite a identificação de um cenário sobre mudanças na granulometria do ROM para os próximos anos. As metodologias foram desenvolvidas para proceder no futuro com a análise de materiais mais resistentes e se tornam de grande valia, pois a tendência do material é se tornar cada vez mais compacto. Desta forma, os resultados defendem este tipo de amostragem como uma técnica viável e sugerem sua utilização para controle de produtividade em outros depósitos. / Feed size distribution curves in crushing stages allows modeling and predict performance of crushers. This research was based on particle size’s distribution curves determination with start on studies about sampling theory from Gy, Napier-Munn, Minnitt e Pittard, however, the sampling was developed with image analysis techniques and not by conventional granulometry analysis (screening). The importance of this research is related to the necessity of knowing ore that feeds plant because, in this study, with increased pit ore is becoming stronger and resistant. One of the essential objective is to use sampling with image analysis techniques as a tool for determining ROM’s particle size that feeds the first stage of crushing plant and apply that techniques in other stages. It was defined two methodologies, one was developed to sample in situ the ROM granulometry that feeds the first crushing stage and the other one was developed specially to knows the particle size (granulometry) that feeds the third crushing stage. Initially, on sampling ROM (friable itabirite), it was identified the workbench to dump a mass of 259t. Big blocks were segregated. In order to measure big blocks were applied image analysis techniques. Smaller material than 2.5cm was screened. Data were processed and analyzed, generating the size distribution curves. The methodology to sampling the third crushing stage (friable itabirite and compact itabirite) began with the sampling point identification followed by recordings and images determination simulating an automatic sampler. Data were processed and analyzed with statistical help to obtain curves. Both methodologies were considered valuable as they provided size distribution curves with reproducibility but were laborious. ROM granulometry that was evaluated has shown insignificant bias and reproducibility errors. The sampling protocol shows high reduction of mass rates. ROM curves shows that 65% of material is retained on APA, 4% is retained in size range between APA and APF and 5% is retained in 1m, showing that front sampled are attending the equipments specifications. With respect to tertiary crushing, two tests were performed. Each image generated one curve and each test generated four curves that generated a medium curve. The medium curve was compared with project curve and the compact curve was the curve that stays closer. The largest errors are, as expects, to blocks of larger size, more than 80mm for compact and 50mm for friable. Also was observed the same material quantity on APA and APF but 100% of compact itabirite was retained in APF, indicating impacts in this operation. The curves analysis allows the identification about changes in ROM’s particle size for the coming years. The methodologies have been developed to proceed in the future with the analysis of more resistant materials and become of great value, because the tendency of the material is becoming increasingly compact. Thus, the results defends this kind of sampling as a viable technique and suggest their use for control of productivity of other mineral deposits.

O trabalho realizado estudou experimentalmente os efeitos do ultra-som terapêutico na prevenção de aderências tendinosas e no reparo tendíneo. Foi selecionado para o estudo o tendão flexor profundo do 3º dedo na transição das zonas 3 e 4 da pata dianteira direita de coelho. Foram utilizados 30 coelhos fêmeas adultas jovens, com peso corporal médio de 2,7 Kg, divididos em 3 grupos (A, B e C) de 10 animais, sob anestesia para a produção da lesão no tendão, feita por escarificação com o uso do bisturi e o esmagamento num segmento de 5 mm de diâmetro, utilizando um dispositivo de carga de 15 Kg, durante 10 minutos. As patas foram imobilizadas com órtese de material termoplástico durante todo o período experimental (21 dias). O ultra som terapêutico foi iniciado no 3º PO, e continuado por 7 dias consecutivos, com 5 minutos de duração. Foi empregado um ultra-som terapêutico, regulado na freqüência de 3 MHz, no modo contínuo, sendo que a intensidade de 0,2 W/'CM POT.2' foi aplicada nos animais do grupo A, 0,4 W/'CM POT.2' no grupo B e ultra-som desligado como placebo no grupo C. No 21º PO os animais foram sacrificados, e o tendão submetido à análise histológica. Os resultados foram submetidos à análise estatística e demonstraram que houve uma menor formação de aderência no grupo A. A aceleração do reparo tendinoso foi observada em todos os grupos / The work accomplished studied experimentally the effects of therapeutics ultrasound in prevention of tendon adherences and in tendon repair. The deep flexor tendon of the 3rd finger between zones 3 and 4 of a rabbit's right fore-foot was selected for the study. Thirty young adult female rabbits, with a body weight average of 2.7 Kg, divided into 3 groups (A, B, and C) of 10 animals each, were used. The tendon injury was made, under the effect of anesthesia, by reaming with the use of a scalpel, and the 5mm diameter crushing was made by the use of a device of 15 Kg load for 10 minutes. The feet were immobilized with orthesis made of thermoplastic material during all the experiment period (21 days). A therapeutics ultrasound, set at the frequency of 3 MHz, was applied. The intensity of 0.2 W/'CM POT.2' was applied to the animals of group A; 0.4 W/'CM POT.2' to the group B; and the equipment was off when applied to group C as a placebo. The therapeutics ultrasound was started in the 3rd PO and kept on for 7 consecutive days, with a duration of 5 minutes. On the 21st day the animals were sacrificed; the tendon was analysed histologically. The results were analysed statistically and showed that there was a minor adherence formation in group A. The acceleration of the tendon repair was observed in all groups

High and medium-pressure roller crushers operate on the principle of inter-particle crushing by crushing material in a packed bed. Although reference in the study is made to high-pressure roller crushers, the work was done with medium–pressure roller crushers i.e. the Loesche mill and the Horomill. The difference in pressures between these equipment and high-pressure grinding rolls (HPGR) from measurements done by FCB, the supplier of the Horomill, was that the medium-pressure equipment operates at pressures of 30 MPa whilst the HPGR operates at pressures as high as 100 MPa. In this study, the differences between single particle and inter-particle crushing and the applicability of the batch press to predict the energy consumption and particle size distributions for medium-pressure roller crushers were investigated. Two phases of crushing were identified and investigated. The first phase occurs when the material is still being drawn into the gap between the rollers. The second phase, called packed bed crushing, occurs when the material is in the gap between the rollers. Crushing and milling energy requirements are discussed with specific reference to the energy models proposed by Bond and Rittinger along with the shortcomings of both these models. These models postulate that the comminution energy is an inverse function of product size. This is proven to be true in this study, but where certain constants are suggested in the aforementioned correlations, this study revealed that these constants are not fixed for all applications but varies for different types of ore. The results were determined for 80% as well as 50% mass passing size. Kick proposed that the energy requirements are a function of the reduction ratio. A model used for roller crushers that is similar to what Kick proposed was also investigated. This was also found to be valid but again, the coefficients in the model vary for the different materials. A new method for predicting the work index of an ore for inter-particle crushing was investigated, which involves using a piston press in which a bed of material is pressed to a predetermined pressure. The proposed method was evaluated using pilot test data obtained with a Horomill, as well as with a pilot Loesche mill. The results indicate that the correlation between the batch press and the pilot mills are poor. The Rosin-Rammler description for particle size distribution was applied and compared with other descriptions. The particle size descriptions of products from the batch press and pilot mills were compared and although there are differences, the batch press can be used to prepare material for initial research in a project. From this study it is clear that, especially when tests are done on an unknown ore body, a work index such as Bond’s, cannot be used for plant design and economic studies unless some pilot plant tests are done to confirm the relationship between energy consumed and product size. / Dissertation (MEng)--University of Pretoria, 2012. / gm2014 / Materials Science and Metallurgical Engineering / unrestricted

This thesis deal with stress control of frame of crushing mill of grain with the aim of defining and consequent optimalization of undersized and overlarge parts of the construction. This frame is screwed assembly. Control is static analysis of frame. This analysis use Finite Element Method.

This diploma thesis deals with construction design of a pendulum for the jaw crusher DCJ 700x300. The first part of the thesis is dedicated to treatment of mineral materials with focus on minimizing minerals. The second part deals with devices used for crushing minerals, jaw crushers and their variants in particular. The third part is devoted to specific design of the jaw crusher based on assigned input. The next part deals with construction design of the pendulum and technology of its production exploring weldments and casts. The aim of this thesis is to perform a strength analysis of the chosen version of pendulum production using the FEM method. The diploma thesis includes drawing documentation of the jaw crusher and the pendulum.

Indiana University-Purdue University Indianapolis (IUPUI) / Design optimization of composite structures is of importance in the automotive, aerospace, and energy industry. The majority of optimization methods applied to laminated composites consider linear or simplified nonlinear models. Also, various techniques lack the ability to consider the composite failure criteria. Using artificial neural networks approximates the objective function to make it possible to use other techniques to solve the optimization problem. The present work describes an optimization process used to find the optimum design to meet crashworthiness requirements which includes minimizing peak crushing force and specific energy absorption for a square tube. The design variables include the number of plies, ply angle and ply thickness of the square tube. To obtain an effective approximation an artificial neural network (ANN) is used. Training data for the artificial neural network is obtained by crash analysis of a square tube for various samples using LS DYNA. The sampling plan is created using Latin Hypercube Sampling. The square tube is considered to be impacted by the rigid wall with fixed velocity and rigid body acceleration, force versus displacement curves are plotted to obtain values for crushing force, deceleration, crush length and specific energy absorbed. The optimized values for the square tube to fulfill the crashworthiness requirements are obtained using an artificial neural network combined with Multi-Objective Genetic Algorithms (MOGA). MOGA finds optimum values in the feasible design space. Optimal solutions obtained are presented by the Pareto frontier curve. The optimization is performed with accuracy considering 5% error.

Die vorliegende Arbeit beschäftigt sich mit der Erarbeitung analytischer beziehungsweise semi-empirischer Modellansätze zur Abbildung der mahltrocknungstypischen Prozesse Zerkleinerung, Trocknung und Beförderung innerhalb der in konventionellen Kohlekraftwerken zur Brennstoffaufbereitung genutzten Kohlemühlen. Die Modellansätze wurden anschließend in jeweils einem Kohlemühlenmodell zur Steinkohleaufbereitung (Walzenschüsselmühle) und zur Braunkohleaufbereitung (Schlagradmühle) zusammengeführt. Eine Validierung wurde für das Walzenschüsselmühlenmodell anhand von Mahltrocknungsversuchen im Technikumsmaßstab und im Kraftwerksmaßstab durchgeführt. Das Abbildungsvermögen des Modells beläuft sich hierbei auf die Partikelgrößenverteilung des aufgemahlenen Kohlestaubes am Mühlenaustrag, dessen Restfeuchtegehalt, die Druckdifferenz zwischen Mühlenein- und -auslass, dem Ein- und Ausspeichervermögen, sowie der Traggastemperatur am Mühlenauslass. Die Validierung ergab hierbei gute Übereinstimmungen der berechneten und gemessenen Werte im Technikumsmaßstab. Im Kraftwerksmaßstab zeigten sich Defizite hinsichtlich des Restfeuchtegehalts des Kohlestaubes am Auslass und der Druckdifferenz über dem Mühlenkörper.:Inhalt 1. MOTIVATION 1 2. GRUNDLAGEN DER MAHLTROCKNUNG 2 2.1. Mahltrocknung 3 2.2. Zerkleinerung und Bruchtheorie 4 2.3. Trocknung 6 2.4. Stand des Wissens – Walzenschüsselmühlen 10 2.5. Stand des Wissens – Schlagradmühlen 13 2.6. Vorhandene Mühlenmodelle 14 2.6.1. Analytische Walzenschüsselmühlenmodelle 14 2.6.2. Parametermodelle Walzenschüsselmühle 19 2.6.3. Numerische Schlagradmühlenmodelle 20 2.6.4. Analytische Schlagradmühlenmodelle 22 2.7. Zwischenfazit 23 3. MODELLIERUNG MAHLTROCKNUNGSSPEZIFISCHER PROZESSE 24 3.1. Zerkleinerung und Aufmahlung 24 3.2. Trocknung 30 3.2.1. Stoffübergang im ersten Trocknungsabschnitt 31 3.2.2. Stoffübergang im zweiten Trocknungsabschnitt 34 3.2.3. Thermische Wechselwirkungen zwischen Traggas und suspendierter Kohle 41 3.3. Partikeltransport 43 3.3.1. Transportgleichung 43 3.3.2. Charakterisierung des Strömungsprofils und Stoffwerte 45 3.3.3. Ermittlung der Traggastemperatur 46 3.3.4. Druckverlust 49 4. MODELLIERUNG WALZENSCHÜSSELMÜHLE 49 4.1. Modellanforderungen 49 4.2. Walzenschüsselmühle - Aufbau und Modellierung 50 4.3. Walzenschüsselmühle – Aufmahlungsprozess 54 4.4. Walzenschüsselmühle – Trocknungsprozess 59 4.5. Walzenschüsselmühle – Partikeltransport 62 4.5.1. Lösung Transportgleichung und Erfassung von Größen 62 4.5.2. Druckverlust durch Reibung und Partikeltransport 66 4.5.3. Sichtungsprozess Walzenschüsselmühle 67 5. MODELLIERUNG SCHLAGRADMÜHLE 70 5.1. Schlagradmühle - Aufbau und Modellierung 70 5.2. Schlagradmühle – Zerkleinerungsprozess 73 5.3. Schlagradmühle – Trocknungsprozess 77 5.4. Schlagradmühle – Partikeltransport 79 5.4.1. Transport im Rauchgasrücksaugschacht 80 5.4.2. Transport in Partikelsteigleitung 81 5.4.3. Sichtungsprozess Schlagradmühle 81 6. VALIDIERUNG 83 6.1. Plausibilitätsprüfung 84 6.1.1. Parametervariation im Teilmodell „Zerkleinerung“ 84 6.1.2. Parametervariation im Teilmodell „Trocknung“ 101 6.1.3. Analyse der Dynamik im Teilmodell „Transport“ 111 6.1.4. Zwischenfazit Plausibilitätsprüfung 119 6.2. Validierungsversuche im Mühlenlabor Stuttgart 119 6.2.1. Versuchsanlage und Brennstoffe 119 6.2.2. Isokinetik der Probenahme 123 6.2.3. Versuchsaufbau und -durchführung 125 6.2.4. Simulationsergebnisse Versuchsplan 126 6.3. Mühlenversuche Großkraftwerk Mannheim 142 6.3.1. Versuchsanlage und Brennstoffe 142 6.3.2. Versuchsaufbau und -durchführung 145 6.3.3. Simulationsergebnisse Versuchsplan 145 7. ZUSAMMENFASSUNG UND AUSBLICK 152 I. FORMELVERZEICHNIS 155 II. QUELLENVERZEICHNIS 161 III. ABBILDUNGS- UND TABELLENVERZEICHNIS 167 ANHANG 174 a. Ergebnisse Plausibilitätsprüfung Teilmodell „Zerkleinerung“ 175 b. Plausibilitätsprüfung Teilmodell „Trocknung“ 200 c. Ergebnisse Plausibilitätsprüfung Teilmodell “Transport” 228 d. Bestimmung Regressionspolynom Sichtung 236

No description available.

Lower-cost manufacturing methods have increased the anticipation for economical mass production of vehicles manufactured from composite materials. One of the potential applications of composite materials in vehicles is in energy-absorbing components such as hollow shells and struts (these components may be in the form of circular cylindrical shells, square and rectangular tubes, conical shells, and frusta). However, constructions which result in brittle fracture of the composite tubes in the form of circumferential or longitudinal corner crack propagation may lead to unstable collapse failure mode and concomitant very low energy absorption. As a result, metal-composite hollow tubes have been developed that combine the benefits of stable ductile collapse of the metal (which can absorb crushing energy in a controlled manner) and the high strength-to-weight ratio of the composites. The relative and absolute thicknesses of metal or FRP section has a substantial effect on energy absorption of the hybrid tubes. In particular, likelihood of delamination occurrence raises with increase in FRP thickness. This can reduce the energy absorption capability of the metal-FRP hybrid tubes. Additionally, adding a very thick FRP section may result in a global buckling failure mode (rather than local folding). Until now, there are no studies specifically addressing the effect of FRP thickness on energy absorption of hybrid tubes. In this study, the effects of fiber orientation and FRP thickness (the number of layers) on the energy absorption of S2-glass/epoxy-304 stainless steel square tubes were experimentally investigated. In addition, a new geometrical trigger was demonstrated which has positive effects on the collapse modes, delamination in the FRP, and the crush load efficiency of the hybrid tube. To complete this study, a new methodology including the combination of experimental results, numerical modeling, and a multi-objective optimization process was introduced to obtain the best combination of design variables for hybrid metal-composite tubes for crashworthiness applications. The experimental results for the S2 glass/epoxy-304 stainless steel square tubes with different configurations tested under quasi-static compression loading were used to validate numerical models implemented in LS-DYNA software. The models were able to capture progressive failure mechanisms of the hybrid tubes. In addition, the effects of the design variables on the energy absorption and failure modes of the hybrid tubes were explained. Subsequently, the results from the numerical models were used to obtain optimum crashworthiness functions. The load efficiency factor (the ratio of mean crushing load to maximum load) and ratio between the difference of mean crushing load of hybrid and metal tube and thickness of the FRP section were introduced as objective functions. To connect the variables and the functions, back-propagation artificial neural networks (ANN) were used. The Non-dominated Sorting Genetic Algorithm–II (NSGAII) was applied to the constructed ANNs to obtain optimal results. The results were presented in the form of Pareto frontiers to help designers choose optimized configurations based on their manufacturing limitations. Such restrictions may include, but are not limited to, cost (related to the number of layers), laminate architecture (fiber orientation and stacking sequence) which can be constrained by the manufacturing techniques (i.e. filament winding) and thickness (as an example of physical constraints). / Ph. D.

This master’s thesis deals with the obtuse-angled cone crushers especially about design of the individual parts of the adjustment mechanism. Most space is devoted to functional calculation and subsequent technical construction of the new design of obtuse-angled crusher where the output setting is adjusted using the motion thread and hydraulic locking system for compensating the thread clearance. The parameters are chosen with regard to the already established older types of cone crushers produced by PSP Engineering, a.s. An inseparable part is the calculation verifying the functionality of the motion thread and gearing. Another essential part of this work are stress analysis of the slot adjusting mechanism design using finite element method and considering two states - adjusting of the slot and crushing itself.