No description available.

The thermal control of a die is crucial for the development of high efficiency injection moulds. For successful thermal management, this research provides an effective control strategy to find sensor locations, identify thermal dynamic models, and design controllers. By applying a clustering method and sensitivity analysis, sensor locations are identified. The neural network and finite element analysis techniques enable the modeling to deal with various cycle-times for the moulding process and uncertain dynamics of a die. A combination of off-line training through finite element analysis and training using on-line learning algorithms and experimental data is used for the system identification. Based on the system identification which is experimentally validated using a real system, controllers are designed using fuzzy-logic and self-adaptive PID methods with backpropagation (BP) and radial basis function (RBF) neural networks to tune control parameters. Direct adaptive inverse control and additive feedforward control by adding direct adaptive inverse control to self-adaptive PID controllers are also provided. Through a comparative study, each controller’s performance is verified in terms of response time and tracking accuracy under different moulding processes with multiple cycle-times. Additionally, the improved cooling effectiveness of the conformal cooling channel designed in this study is presented by comparing with a conventional straight channel.

No description available.

Wood is a natural and renewable resource and, moreover, a most decorative and beautiful material. Most valuable logs are used for veneer production for optimum exploitation and utilization. Attractive wood veneers adorn any surface and is primarily used for furniture, yacht and automotive interior works. However, such application of wood veneer is limited to rather simply shaped carrier components due to the veneer’s mechanical restrictions. Previously, several approaches have been discussed to flexibilize wood allowing a greater deformation, but none approach has been entirely satisfactory. On that score, another veneer modification process has been suggested comprising a furfuryl alcohol impregnation to plasticize the wood veneer realizing enhanced veneer flexibility and mouldability (Pfriem and Buchelt 2011b). In the presence of a suitable initiator and promoted by elevated temperatures, furfuryl alcohol forms a very hard, insoluble polymer inside the wood cell walls. If polymerization is initiated as the impregnated veneer is moulded, the polymer is assumed to fix the gained shape. This thesis summarizes experimental work investigating the effect of furfuryl alcohol modification on maple veneer plasticization, shape fixation, and shape stability and the impact of various process parameters on material characteristics. Veneer samples impregnated with furfuryl alcohol exhibited an increased cell wall swelling, were notably softer than dry reference veneer, and showed an enhanced mouldability comparable to water impregnated veneer samples. Each characteristic is indicative for an increased plasticization. DSC studies were carried out to assess the influence of various initiator contents and ethanol dilutions of the impregnation liquid on the curing reactions and the retained polymer yield. Thereby, high initiator contents promoted a more rapid curing at lower temperatures with higher polymer yields, whereas higher dilution shifted the curing towards higher temperatures and possibly retard the curing resulting in lower polymer yields. The furfuryl alcohol polymer retaining inside the cell walls was proved to fix the achieved shape of veneer providing moreover enhanced shape stability at elevated temperatures and increasing moisture compared to unmodified reference veneer samples. According to these findings, furfuryl alcohol modification can be used for wood veneer plasticization and improved mouldability, shape fixation, and stabilization. However, material properties vary notably with changing process parameters. / Holz ist nicht nur eine natürlicher und nachwachsender Rohstoff, sondern vielmehr auch ein sehr dekoratives und schönes Material. Die wertvollsten Baumstämme werden daher häufig zur Furnierproduktion genutzt, um diese raren Stämme bestmöglich auszunutzen und zu verwerten. Besonders schöne Furniere schmücken jegliche Oberfläche und werden vorallem in der Möbelindustrie, sowie beim Yacht- und Autoinnenausbau verwendet. Jedoch ist die Anwendung aufgrund mechanischer Restriktionen auf eher einfach geformte Oberflächen und Trägerteile begrenzt. In der Vergangenheit wurden unterschiedliche Methoden entwickelt, um den Einsatzbereich von Furnieren durch eine erhöhte Flexibilität und Verformbarkeit auszuweiten, jedoch ist keiner dieser Prozesse in allen Aspekten zufriedenstellend. Aus diesem Grund wurde von Pfriem und Buchelt (2011b) eine neue Methode vorgeschlagen. Hierbei sollen Furniere mit Furfurylalkohol imprägniert werden, um einerseits die Furniere zu plastifizieren und eine erhöhte Flexibilität und Umformbarkeit zu ermöglichen. Andererseits härtet Furfurylalkohol in Gegenwart eines geeigneten Initiators und durch erhöhte Temperaturen begünstigt aus und bildet in den Zellwänden ein hartes, weitestgehend unlösliches Polymer aus. Hierbei wird angestrebt, die Polymerisation zu initiieren, wenn das imprägnierte Furnier bereits umgeformt ist, so dass das entstehende Polymer das Furnier im umgeformten Zustand fixiert. Die vorliegende Dissertation fasst die erzielten Ergebnisse von Experimenten zusammen, die durchgeführt wurden, um die plastifizierende Wirkung von Furfurylalkohol auf Ahornfurniere sowie die formfixierende und stabilisierende Eigenschaft des ausgehärteten Polymers zu untersuchen und den Einfluss unterschiedlicher Prozessparameter auf erzielte Materialeigenschaften zu bestimmen. Es konnte nachgewiesen werden, dass durch die Imprägnierung mit Furfurylalkohol ein Quellen der Zellwände verursacht wird und dass die getränkten Proben deutlich weicher sind als die Referenzproben und eine erhöhte Umformung aufwiesen. Diese erzielten Änderungen weisen auf eine deutliche Plastifizierung der Holzsubstanz hin. DSC-Analysen von Furnieren, die mit unterschiedlich zusammengesetzten Imprägnierflüssigkeiten auf Basis von Furfurylalkohol imprägniert wurden, belegen den Einfluss unterschiedlicher Initiatoranteile und Verdünnungen mit Ethanol auf die Polymerisation. Während höhere Anteile an Initiator eine rasche Reaktion bei niedrigeren Temperaturen und einen hohen Beladungsgrad hervorrufen, bewirken starke Verdünnungen des Furfurylalkohols mit Ethanol eine Verzögerung der Polymerisation und eine Verschiebung dieser zu höheren Temperaturen bei gleichzeitigen vergleichsweise geringen Beladungsgraden. Mit weiteren Versuchen konnte bestätigt werden, dass das Polymer des Furfurylalkohols in den Zellwänden die erzielte Umformung der Furniere fixiert und auch bei höheren Temperaturen und Luftfeuchten eine erhöhte Formstabilität bewirkt. Die Versuche haben gezeigt, dass Furfurylalkohol zur Plastifizierung und verbesserten Umformbarkeit von Furnieren sowie zu deren Formfixierung und Formstabilisierung genutzt werden kann, allerdings variieren die Materialeigenschaften mit unterschiedlichen Prozessparametern insbesondere mit unterschiedlichen Initiatoranteilen in der Imprägnierflüssigkeit.

The thermal control of a die is crucial for the development of high efficiency injection moulds. For successful thermal management, this research provides an effective control strategy to find sensor locations, identify thermal dynamic models, and design controllers. By applying a clustering method and sensitivity analysis, sensor locations are identified. The neural network and finite element analysis techniques enable the modeling to deal with various cycle-times for the moulding process and uncertain dynamics of a die. A combination of off-line training through finite element analysis and training using on-line learning algorithms and experimental data is used for the system identification. Based on the system identification which is experimentally validated using a real system, controllers are designed using fuzzy-logic and self-adaptive PID methods with backpropagation (BP) and radial basis function (RBF) neural networks to tune control parameters. Direct adaptive inverse control and additive feedforward control by adding direct adaptive inverse control to self-adaptive PID controllers are also provided. Through a comparative study, each controller’s performance is verified in terms of response time and tracking accuracy under different moulding processes with multiple cycle-times. Additionally, the improved cooling effectiveness of the conformal cooling channel designed in this study is presented by comparing with a conventional straight channel.

The use of ultrafast lasers in material surface engineering has gained pre-eminence in recent years. This is due to optimal utility arising from their versatility, better process control, repeatability and high precision fabrication, without need for post processing. Reported in this thesis are experimental results on the use of picosecond laser to produce micro-patterns on cyclone components and their effects on flow characteristics. Results show that micro- dimples achieved reduction in dust accumulation within a multi-cyclone system considered, up to 78%. These micro-dimples when applied on the cyclone roof effected a 3% reduction in inlet velocity and 5% reduction on the dynamic pressure across the cyclone, without dust introduction. Results support the possibility for energy savings, without compromise on cyclone overall separation efficiency. Findings further demonstrated the effects of micro-riblets on cyclonic airflow at the wall boundary. Research outcomes supported the view that surface roughness of the cyclone roof could contribute on its dust separation capacity. Injection moulding was used to produce bumps on ABS plastic materials utilising picosecond laser machined micro-dimples on H13 tool steel. A statistical model detailing the interactions between the critical factors involved with picosecond laser interaction with H13 for micro-patterning was proposed. Critical factors identified were laser fluence, scanning speed and number of laser scans. In addition, results demonstrated the suitability of predicting depth of 40 - 100 µm for H13 tool steel, with 96% accuracy. The findings in this research could be explored to develop embedded micro/nano-wires within riblets through injection moulding, to effect electrically biased charging within the internal walls of a cyclone to aid dust separation processes.

This thesis investigates the cooling behaviour of polymers during the microinjection moulding process. The work included bespoke experimental mould design and manufacturing, material characterisation, infra-red temperature measurements, cooling analysis and cooling prediction using commercial simulation software. To measure surface temperature of the polymers, compounding of polypropylene and polystyrene with carbon black masterbatch was performed to make materials opaque for the IR camera. The effects of addition of carbon black masterbatch were analysed using differential scanning calorimetry and Fourier transform infrared spectroscopy. Sapphire windows formed part of the mould wall and allowed thermal measurements using an IR camera. They were laser machined on their inside surfaces to generate a range of finishes and structures. Their topographies were analysed using laser confocal microscope. The surface energy of sapphire windows was measured and compared to typical mould steel, employing a contact angle measurement technique and calculated using Owens-Wendt theory. A heating chamber was designed and manufactured to study spreading of polymer melts on sapphire and steel substrates. A design of experiments approach was taken to investigate the influence of surface finish and the main processing parameters on polymer cooling during microinjection moulding. Cooling curves were obtained over an area of 1.92 by 1.92 mm of the sapphire window. These experiments were conducted on the Battenfeld Microsystem 50 microinjection moulding machine. A simulation study of polymer cooling during the microinjection moulding process was performed using Moldflow software. Particular interest was paid to the effect of the values of the interfacial heat transfer coefficient (HTC) on the simulated cooling predictions. Predicted temperature curves were compared to experimentally obtained temperature distributions, to obtain HTC values valid for the material and processing parameters.

End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the < cos2θ > for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting < cos2θ >. The breakage prediction improves if measured FLD of the extrudate is input into the model.

Le fragment du corps moulé, le corps qui s’effondre, réduit à une dépouille, la figure qui tend à s’effacer, se regardent comme les bribes d’une mémoire où coexiste un double mouvement : le contact et la séparation, la présence et l’écart. L’empreinte du corps en creux, signale que rien ne sera plus jamais comme avant. Le moulage dit ce qui est. Il dit le « mort » par son empreinte vivante : ce que j’ai moulé, photographié cet « incomparable air de vie » a disparu. Irrémédiablement. Pièces à conviction qui calment la perte, les fragments, le travail parfois sériel conspirent contre l’oubli, attestent d’un passage et d’une présence dont je refuse qu’ils passent, s’effacent. La séparation définitive est insupportable. C’est dans la présence de la figure déposée, devenu fragment de mémoire et dans son absence que se dialectise alors l’inacceptable et devient possible son acceptation. L’impossibilité de ralentir le cycle du temps impose toujours le sentiment d’une urgence. Mon travail est résistance. Il pose un regard mélancolique sur les choses qui changent, passent, nous échappent. Rien ne s’arrête, rien n’est défini de façon satisfaisante. C’est une réalité qui se fait à travers celle qui se défait. Une avancée se noue sur ce qui s’use ou se troue. Faire contrepoids à cette ombre omniprésente. Choisir dans les différentes ouvertures possibles, à travers le cortège des images, des figures, des choses obsédantes et trouver, provisoire, fragile et lacunaire, une réponse. / The fragment of a moulded body, the body which collapses, is reduced to a corpse,the figure which tends to disappear, can be seen like pieces of a memory in which a double movement co-exists : the contact and the separation, the presence and the gap. The print of the body in hollow shows that nothing will never be like before anymore. The moulding says what exists. It says « the dead » by its living print : what I have moulded, photographed, this « incomparable air of life » disappeared. Irredeemably. Exhibits which calm the loss, the fragments, the work in series conspire against oblivion, prove the passage and a presence I refuse them to disappear. The definitive separation is unbearable. It is in the presence of the figure that I exhibit, which has become « fragment of memory » and in its absence that dialectises then in the unacceptable and its acceptance has become possible. The impossibility to slow down the cycle of time always imposes the feeling of urgency. My work is resistance. It poses a melancholic look on the things that change, pass away and that aren’t under control. Nothing stops, nothing is defined in a satisfactory way. It is a reality which is made through the one that unties. An advance ties on what is worn up or what bores a hole. Counterbalancing.this omnipresent shadow. Choosing in the different possible openings throughout a cortege of images, figures, obsessive things and finding a provisional, fragile, incomplete answer.

Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-08-14T15:07:01Z No. of bitstreams: 2 Dissertação - Tacilene C Pereira.pdf: 1083588 bytes, checksum: 3e45d91b1fe0e44c3b1635175094f4cb (MD5) Ficha Catalográfica.pdf: 1873 bytes, checksum: e1ff88255d2c3bc6dd8b7123f1f532a7 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-18T19:53:57Z (GMT) No. of bitstreams: 2 Dissertação - Tacilene C Pereira.pdf: 1083588 bytes, checksum: 3e45d91b1fe0e44c3b1635175094f4cb (MD5) Ficha Catalográfica.pdf: 1873 bytes, checksum: e1ff88255d2c3bc6dd8b7123f1f532a7 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-18T19:58:37Z (GMT) No. of bitstreams: 2 Dissertação - Tacilene C Pereira.pdf: 1083588 bytes, checksum: 3e45d91b1fe0e44c3b1635175094f4cb (MD5) Ficha Catalográfica.pdf: 1873 bytes, checksum: e1ff88255d2c3bc6dd8b7123f1f532a7 (MD5) / Made available in DSpace on 2015-08-18T19:58:37Z (GMT). No. of bitstreams: 2 Dissertação - Tacilene C Pereira.pdf: 1083588 bytes, checksum: 3e45d91b1fe0e44c3b1635175094f4cb (MD5) Ficha Catalográfica.pdf: 1873 bytes, checksum: e1ff88255d2c3bc6dd8b7123f1f532a7 (MD5) Previous issue date: 2015-06-15 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This piece of work aims to make clear the Mathematics Moulding as an excellent strategy of teaching that makes possible to the student investigate, discuss and search to understand through mathematics instruments, situations of his quotidian. Two mouldings are presented in this work, specifically the model of Malthus, that were achieved with secondary students, one related to pregnancy in adolescence and another dealing with analphabetism in Brazil, common themes in the quotidian of the student. / Este trabalho visa evidenciar a ModelagemMatemática como excelente estratégia de ensino que possibilita ao aluno investigar, questionar, e buscar compreender, por meio de instrumentos matemáticos, situações do seu cotidiano. Nele são apresentadas duas modelagens, especificamente do modelo de Malthus, que foram realizadas com alunos do Ensino Médio, um relacionado a gravidez na adolescência e outro tratando do analfabetismo no Brasil, temas comuns ao cotidiano do aluno.