Composite materials offer a high strength-to-weight ratio and directional load bearing capabilities. Compression molding of composite materials yields a superior surface finish and good dimensional stability between component lots with faster processing compared to traditional manufacturing methods. This experimental compression molding capability was developed for the ME composites lab using unidirectional carbon fiber prepreg composites. A direct comparison was drawn between autoclave and compression molding methods to validate compression molding as an alternative manufacturing method in that lab. A method of manufacturing chopped fiber from existing unidirectional prepreg materials was developed and evaluated using destructive testing methods. The results from testing both the continuous and chopped fiber were incorporated into the design of a functionally graded hybrid continuous and chopped carbon fiber component, the manufacture of which resulted in zero waste prepreg material.

The manufacture, laminate design, and modeling of a part with complex geometry are explored. The ultimate goal of the research is to produce a model that accurately predicts part stiffness. This is validated with experimental results of composite parts, which refine material properties for use in a final prototype part model. The secondary goal of this project is to explore manufacturing methods for improved manufacturability of the complex part. The manufacturing portion of the thesis and feedback into material model has incorporated a senior project team to perform research on manufacturing and create composite part to be used for experimental testing. The senior project was designed, led, and managed by the author with support from the committee chair. Finite element modeling was refined using data from coupon 3-point bend testing to improve estimates on material properties. These properties were fed into a prototype part model which predicted deflection of composite parts with different layups and materials. The results of the model were compared to experimental results from prototype part testing and 3rd party analysis. The results showed that an accurate mid-plane shell element model could be used to accurately predict deflection for 2 of 3 experimental parts. There are recommendations in the thesis to further validate the models and experimental testing.

This master's thesis is focused on analyzing problems during the execution of contracts selected company, which deals with custom manufacturing thermoplastic injection molding. The thesis proposed possible solutions for identified problems.

The thesis is focused on proposal of automatic transport feeder that can be used for injection moulding machines. It is concerned with conveyor belt, gravitational roller line and lift. Proposal of construction of automatic transport feeder, calculation of drive for conveyor belt and driven line is contained in this thesis. There is calculation of driveshaft, proposal of spring and calculation of bearing lifetime. Angle of conveyor of gravimetric roller line and speed at the end are calculated. Calculation of proposal of drive for lift and proposal of drive roller line on the lift is here. This thesis contains senzor, operation and steering, safety protection of feeder. There are applicability of robotic workplace and economic calculation at the end of thesis.

This thesis deals with optimization of manufacturing process of plastic molded parts production. The first part focuses of describing current workplace, thanks to that was found out amount of transported materials. In second part there are two possibilities of solving problem with target to decrease amount of manipulations and transports. On base of this evaluation this these variants, the optimal variant is choosen. This variation improve molding process, decrease number of manipulation equipments and number of operators.

This diploma thesis deals with the development, disign and manufacturing inspection device that is able to detect the presence of components in the assembly of the plastic molding. Evaluation of information are indicated by the operator device and sent for further processing. Rechecked product will be marked with a uniquemark.

Les lignes de soudure apparaissent fréquemment par moulage par injection lorsque des fronts séparés de polymère fondu se rencontrent. Elles induisent une réduction significative de la résistance à la rupture et de la déformation, en particulier pour les composites. Il est donc essentiel de prévoir de façon fiable leurs propriétés mécaniques pendant la phase de conception du produit, mais les outils de simulation actuels ne sont pas encore en mesure de le faire. La littérature met en évidence deux raisons principales : une diffusion macromoléculaire incomplète de la matrice polymère aux interfaces et un changement de la distribution d'orientation des fibres. Ce travail s’est donné pour objectif de caractériser et de quantifier la contribution de ces facteurs et de contribuer à améliorer la prédiction des propriétés mécaniques des polymères renforcés de fibres courtes moulés par injection.Des échantillons en PBT renforcé de fibres de verre à 30 % en poids ont été moulées avec des lignes de soudure frontale et fuyante. Les déformations dans les essais mécaniques ont été mesurées par corrélation d'images numériques pour quantifier la localisation dans les lignes de soudure. La microstructure a été déterminée par tomographie X. Nous avons pu notamment montrer que les lignes de soudure fuyantes ne s’estompaient que très lentement et que les fronts de matière se comportent vis-à-vis de l’autre comme des parois. Un modèle physique basé sur la théorie de la reptation a été mis en œuvre pour déterminer un critère de cicatrisation de l’interface. En utilisant la distribution d’orientation mesurée et un schéma d'homogénéisation adéquat pour chaque élément dans une simulation par éléments finis, les propriétés mécaniques jusqu’à la rupture du composite ont pu être calculés et expliquent la réduction des propriétés mécaniques au niveau des lignes de soudure, sachant que les interfaces étaient entièrement cicatrisées pour le matériau de l’étude. Enfin, pour cette matrice semi-cristalline, nous avons montré la nécessité d’utiliser une loi de comportement élastoplastique avec un seuil d’endommagement dépendant de l’orientation des fibres. / Weld Lines frequently appear by injection molding when separate polymer melt fronts meet. They induce a significant reduction in the failure strength and strain, especially for composites. It is therefore essential to predict reliably their mechanical properties during the product design phase, but current simulation tools are still not able to do it. Literature points to two main reasons of WL weakness: an incomplete polymer matrix healing and a change in the fiber orientation distribution. The objective of this work is to characterize and quantify the contribution of these factors and to contribute to improving the prediction of the mechanical properties of injection molded short-fiber reinforced polymers.Samples of 30 % wt. glass fiber-reinforced PBT were injection molded with frontal and flowing weld lines. The deformations in the mechanical tests were measured by of digital image correlation to quantify the location of deformation in the weld lines. The microstructure was quantified using X-ray computed tomography scans. In particular, we were able to show that the flowing weld lines were fading very slowly and that the material fronts behave towards each other like walls. A physical model based on reptation theory was implemented to determine a criterion for interface healing. Using the measured orientation distribution and an appropriate homogenization scheme for each element of a finite elements simulation, the mechanical properties up to the failure of the composite could be calculated and explain the reduction in mechanical properties at the weld lines, knowing that the interfaces were fully healed for the study material. Finally, for this semi-crystalline polymer, we have shown the need to use an elastoplastic constitutive law with a damage threshold depending on the orientation of the fibers.

Orientador: Edson Cocchieri Botelho / Resumo: Esta pesquisa visa o processamento de compósitos termorrígidos laminados multifuncionais, via moldagem por compressão a quente, constituídos por fibras de carbono, resina epóxi e mantas de poli(butadieno) (BR) produzidas via processo de eletrofiação. Estas mantas têm como função proporcionar maior tenacidade ao compósito obtido, aumentando sua tolerância ao dano e consequentemente, elevando sua aplicabilidade no setor aeroespacial. Para o desenvolvimento deste trabalho de pesquisa, primeiramente, foram produzidas mantas de poli(butadieno) por eletrofiação. Todas as condições de processamento foram avaliadas nesta etapa do projeto. Posteriormente, estas mantas foram utilizadas para a obtenção de diferentes compósitos com resina epóxi e fibra de carbono, utilizando-se oito distintas configurações, processados via moldagem por compressão a quente. A qualidade dos compósitos fabricados foi avaliada a partir de ensaios de digestão ácida, microscopia, análise dinâmico mecânica (DMA) e inspeção acústica por ultrassom. Com o intuito de se avaliar eventuais ganhos na tenacidade à fratura dos laminados, foram realizados ensaios de excitação por impulso e resistência ao impacto, o qual foi seguido pela técnica de ultrassom. Também foram realizados ensaios de End-Notched Flexure (ENF) pelo modo II de fratura (modo de deslizamento) e ensaios de cisalhamento interlaminar (ILSS) e após os respectivos ensaios, os compósitos também foram avaliados por microscopia. A partir da técnica de eletr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This research aims the processing of multifunctional laminated thermosetting composites by hot compression molding, consisting of carbon fibers, epoxy resin and polybutadiene (BR) mats produced by electrospinning. These mats can provide greater toughness to the composite obtained, increasing its damage tolerance and consequently increasing its applicability in the aerospace field. For the development of this research, polybutadiene mats were produced by the electrospinning process. All processing conditions were evaluated at this stage of the project. Subsequently, these mats were used to obtain different epoxy resin/ carbon fiber composites with 8 distinct configurations, processed by hot compression molding process. The quality of the manufactured composites was evaluated using acid digestion tests, microscopy, dynamic mechanical analysis (DMA) and acustic inspection by ultrasound. After processing, in order to evaluate possible gains in fracture toughness, these laminates were submitted impulse excitation tests, impact resistance, and after tests the specimens were analyzed by ultrasound. Also, End-Notched Flexure (ENF) testes were performed using mode II fracture (sliding mode) and interlaminar shear tests (ILSS) and after the respective tests, the composites were also evaluated by microscopy. Using the electrospinning technique, it was possible to manufacture polybutadiene microfibers successfully, and use them to process laminated composites consisting of carbon fibers ... (Complete abstract click electronic access below) / Doutor

Due to the rising demand of light-weight constructions as well as the conservation of resources, the density and weight of thermoplastic parts could be influenced significantly by using the thermoplastic foam injection molding process. The structure of the foam injection molded part, which typically means solid surface layers and a cellular core, usually results in a weight saving. Furthermore the materials structure leads to an increasing of the specific bending stiffness with a simultaneous low tendency to warp. The present study was aimed to analyze the interactions between microcellular structure, joining process and the resulting mechanical properties of the molded part. Therefore, the microcellular injection molding process (MuCell®) as well as the vibration welding were used. Whereas the established welding processes for solid injection molded parts have already achieved a high degree of perfection within the last decades, the joining of microcellular thermoplastics entails several specific characteristics, because the injection foaming process highly influences the basic material properties. In contrast to solid materials, the weld seam properties after joining are mainly affected by the design constraints of the microcellular structure.

The following paper will illustrate the development of a multiflex chain in hybrid construction. The aim of this novel chain variant is to improve the stiffness and strength in comparison to conventional plastic slide chains. A two part multiflex chain with a chain pitch of 33.5 mm and a structural width of 83 mm was used as the basis for the development of the hybrid multiflex chain. The hybrid multiflex chain is supposed to be integrated in already existing layouts of chain conveyors. The load bearing structure of the single chain links is manufactured in the metal die cast procedure while taking the constructive, production related, and operational aspects into consideration and subsequently covered in the injection molding process with plastics commonly used for multiflex chains. The evaluation of the improved stiffness and strength takes place in the course of extensive test series. / In der folgenden Abhandlung wird die Entwicklung einer Multiflex-Kette in Hybridbauweise erläutert. Mit dieser neuartigen Kettenvariante soll eine Steifigkeits- und Festigkeitssteigerung gegenüber den konventionellen Kunststoffgleitketten erzielt werden. Als Ausgangsbasis für die Entwicklung der hybriden Förderkette dient eine zweiteilig ausgeführte Multiflex-Kette mit der Teilung von 33,5 mm und einer Baubreite von 83 mm. Die hybride Förderkette soll in bestehende Layouts von Kettenförderern integriert werden können. Unter Beachtung konstruktiver, fertigungstechnischer und betrieblicher Aspekte wird die lasttragende Struktur der einzelnen Kettenglieder im Metalldruckgussprozess gefertigt und anschließend mit einem, für Multiflex-Ketten üblichen Kunststoff im Spritzgießprozess ummantelt. Die Evaluierung der Steifigkeits- bzw. Festigkeitssteigerung erfolgt im Rahmen umfangreicher Versuchsreihen.