Deep drawing behaviour of steel-glass fibre-reinforced and non-reinforced polyamide-steel sandwich materials

Thermoplastic-based fibre metal laminates (FMLs) have gained increasing interest in the automotive industry due to their forming potential—especially at higher temperatures—into complex components compared to thermoset-based ones. However, several challenges arise while processing thermoplastic-based FMLs. One the one hand, forming at room temperature (RT) leads to early failure modes, e.g., fracture and delamination. On the other hand, warm forming can extend their forming limits, although further defects arise, such as severe thickness irregularities and wrinkling problems. Therefore, this study focuses on developing different approaches for deep drawing conditions to deliver a promising, feasible, and cost-effective method for deep-drawn FML parts. We also describe the defects experimentally and numerically via the finite element method (FEM). The FMLs based on steel/glass fibre-reinforced polyamide 6 (GF-PA6/steel) are studied under different deep drawing conditions (temperatures, punch, and die dimensions). In addition, mono-materials and sandwich materials without fibre reinforcement are investigated as benchmarks. The results showed that the best deep drawing condition was at a temperature of 200 ◦C and a die/punch radius ratio of 0.67, with a gap/thickness ratio of ≤2.0. The FEM simulation via Abaqus 6.14 was able to successfully replicate the anisotropic properties and wrinkling of the GF-PA6 core in an FML, resembling the experimental results

Sociopolitics profile and Legislative Decisions in 15ª Legislature of the State of the Paraná, São Paulo and Minas Gerais (2003-2007)

Orientador: Valeriano Mendes Ferreira CostaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências HumanasResumo: O objetivo desta dissertação é caracterizar o perfil das decisões legislativas das diversas bancadas partidárias e grupos parlamentares atuantes durante a 15ª Legislatura das Assembléias Legislativas do Paraná, São Paulo e Minas Gerais (2003-2007). Para tanto, vamos aplicar a tipologia desenvolvida por Fabiano Santos (1995) aos projetos de lei aprovados (2821 leis), e efetuaremos cruzamentos estatísticos destas informações com dados sobre o perfil sociopolítico e o padrão de recrutamento dos 227 deputados estaduais, eleitos a legislatura desses três estados. Procuraremos testar a seguinte hipótese: há ou não diferenças significativas entre os padrões de recrutamento e de comportamento político (tal como descrito pela produção legislativa) das várias bancadas partidárias e subgrupos de parlamentares atuantes na Assembléia Legislativa. Em suma: pretendemos demonstrar se os "partidos contam" ou não na arena parlamentar, ao contrário do que afirma boa parte da literatura especializadaAbstract: The objective of this monograph is to characterize the profile of the legislative decisions of diverse partisan group of bencheses and operating parliamentary groups during 15ª Legislature of the State legislatures of the Paraná, São Paulo and Minas Gerais (2003- 2007). For in such a way, we go to apply the tipologia developed for Fabiano Santos (1995) to the approved projects of law (2821 laws), and will effect statistical crossings of these information with data on the sociopolitics profile and the standard of conscription of the 227 state deputies, elect the legislature of these three states. We will look for to test the following hypothesis: it has or not significant differences between the behavior and conscription standards politician (as described for the legislative production) of some partisan group of bencheses and sub-groups of operating parliamentarians in the State legislature. In short: we intend to demonstrate if the "parties count" or not in the parliamentary enclosure for bullfighting, in contrast of what it affirms good part of specialized literatureMestradoCiencia PoliticaMestre em Ciência Polític

Stretching and forming limit curve of steel-glass fibre reinforced and non-reinforced polyamide-steel sandwich materials

This paper focuses on investigating the forming behaviour of sandwich materials composed of steel sheets and glass fibre-reinforced polyamide 6 (GF-PA6), i.e., thermoplastic-based fibre metal laminates (FML). Stretching and forming limit curve (FLC) determination of FML with different cover/core layer thickness ratios at various forming temperatures, i.e., at room temperature (RT), 200 and 235 ◦C, are the main approaches for characterizing their formability. In addition, the formability of mono-materials and non-reinforced sandwich materials is investigated as a reference. For a successful test and reliable results, several technical issues are considered, such as the suitable lubrication configuration and digital image correlation at elevated forming temperatures. The results revealed that the formability of non-reinforced sandwich materials with different core layer thicknesses exhibited compared formability to their monolithic steel sheet and no remarkable improvement in their formability with increasing the temperature up to 200 ◦C. Conversely, the formability of FML shows significant improvement (approx. 300%) with increasing temperature with a forming depth of about 33 mm at 235 ◦C compared to only 12 mm at RT

Urbanisation influences on freshwater fish distribution and remediation of migratory barriers

Ongoing urbanisation in lower stream reaches can adversely affect the ecology of river ecosystems by altering freshwater fish distributions. Diadromous fish species (those that migrate between the sea and freshwater) are particularly affected as unimpeded access to and from the sea is necessary for their life-cycle completion. To investigate the extent of the effects that urbanisation have on migratory freshwater fish species, I compared fish community composition between urbanimpacted and un-impacted waterways in the upper South Island, New Zealand. I also investigated whether culverts were barriers to inanga (Galaxias maculatus) juvenile migration, and experimentally tested different aspects of fish ramp designs for the remediation of juvenile inanga migration barriers. Analyses of fish community composition indicated significant differences between urban-impacted and un-impacted stream reaches. Fish species sensitive to poor habitat quality were generally absent from urban waterways. Inland penetration of fish species was reduced in urban-impacted than un-impacted streams, likely indicating culverts were upstream migration barriers. Laboratory experiments showed that climbing ability of inanga depended on fish size. Climbing also depended on the length and slope of the climb, but not the availability of resting pools. Experiments conducted at 13 natural culverts showed fish could not pass (0% passage) undercut (perched) culverts unless aided by an experimental ramp (44 % passage). To offer successful upstream passage for weak swimming species, culverts should ideally be box-shaped with widths and angles similar to the natural stream bed. Fish ramps should be designed to accommodate species with weak swimming abilities, considering trade-offs in ramp geometry. My results provide a framework for identifying and correcting barriers to diadromous fish passage, allowing managers and ecologists to maintain and enhance fish populations in urban environments

Improvements to the single screw extruder

The extrusion on a single screw extruder is examined. The process is divided into several steps: the dosage of the materials to be conveyed; the modification of the shape of the feeding opening which influences the feeding process and consequently the throughput of the extruder; optimizing the shape of the feeding zone to meet the specific material requirements; and plasticizing and homogenizing

Combination of Carbon Fibre Sheet Moulding Compound and Prepreg Compression Moulding in Aerospace Industry

AbstractThe demand for fuel efficient aircraft led to the development of innovative lightweight constructions and the use of lightweight materials, such as carbon fibre reinforced plastics. In the same manner competences in new production technologies have been built up in the aerospace industry. However, current processes for producing lightweight composites with an excellent mechanical performance cause high costs and long process cycles in comparison with approved metal processes. Furthermore the used raw materials, such as carbon fibres and resin, are very expensive. In contrast to these technologies Sheet Moulding Compound is characterised by a very high productivity, excellent part reproducibility, cost efficiency and the possibility to realise parts with complex geometries and integrated functions, e.g. inserts or colouring. The biggest disadvantage of Sheet Moulding Compound parts is a low level of stiffness and strength because of a low fibre-volume fraction, a short fibre length and isotropic fibre distribution. In this context the combination of Sheet Moulding Compound and Prepreg compression moulding in an one-shot compression moulding and curing process merges the advantages of both materials to create load-bearing and autoclave-quality parts without an autoclave. In the following article, this new technology and its potential will be presented. This paper will also deal with the resulting material characteristics

Mechanical performance evaluation of fiber composites equipped with In-Situ wireless sensor bodies

In modern day structural engineering, fiber-composites play a vital role for their capability for light-weight construction and high stiffness value. More and more applications are being developed in various industries ranging from science, architecture and engineering. These structures can also be equipped with multi-component sensor systems for different performance evaluations both during pre- and post-curing processes. In this work a novel method is developed to place wireless sensors inside the fiber reinforced composite system to enable multifunctionality without much trade-off in mechanical performance. Key objective here was to optimize the sensor shape to minimize stress accumulation and crack propagation around the sensor geometry inside the cured composite sample under stress. A finite element simulation model is developed for this purpose and a parametric model for the sensor geometry provided better insight into the force distribution along the fibers around the sensor element. Consequently, different testing sample combinations were prepared, for which, fibers were either cut or bend around the sensors and dielectric channels. Various composite samples with different shapes of sensor dummies were also experimentally tested to validate the computational results. CT scan models of post-cure samples before and after loading enabled in-depth understanding of fiber alignment that could cause disturbances in overall mechanical performance. The scan models also provided with sufficient information about unwanted porosity, and micro-crack growth inside the composite under loading, which turned out to be vital for establishing a reliable simulation model and improving parameters in manufacturing process. In the end, the goal of the work was to transport the know-how of such production unit from experimental and flexible manufacturing system like vacuum assisted resin infusion (VARI) to more sophisticated processing systems like prepreg manufacturing where all necessary information can be provided as inputs prior to the impregnation, thus removing error occurred due to manual handling

Die Online-Prepregtechnologie: Ein neuartiges, kostengünstiges und ressourcenschonendes Herstellungsverfahren zur Produktion von Faserverbundbauteilen

Der Einsatz von Prepregs ist heute ein wesentlicher Bestandteil der Produktionsstrategie für eine Vielzahl von industriellen Hochleistungsanwendungen. Der primäre Fokus liegt dabei in einer hohen, gleichbleibenden Qualität, sowie einer bereits im Vorfeld erfolgten Zertifizierung der Materialien. Ebenso können die Kompetenzen für die Herstellung und Verarbeitung von faserverstärkten Werkstoffen voneinander getrennt werden. Den Vorteilen dieser Werkstoffklasse steht jedoch auch eine Reihe von Nachteilen gegenüber. Zum Beispiel die energieintensive Kühlung und die vergleichsweise begrenzte Lagerkapazität. Auch die Entsorgung der Verschnitte ist problematisch, da die bereits imprägnierten Textilien nur schwer zu recyceln sind. Das neu entwickelte innovative, ressourcenschonende Herstellungsverfahren für online imprägnierte textile Preforms kann die genannten Nachteile zielgerichtet adressieren. Das daraus resultierende Verfahren mündete in der Entwicklung und Produktion eines Prototypen einer Online-Prepregmaschine zur Herstellung von Bauteilen mit dem innovativen Prozess. Das vorliegende Paper befasst sich mit der detaillierten Beschreibung der Prozesskette, beginnend mit dem automatisch optimierten verschachtelten Zuschnitt von trockenen Textilien nach Wahl, einer anschließenden infrarotüberwachten, thermischen Textiltrocknung, über die konturgenaue Direktimprägnierung ausgewählter Einzeltextillagen, bis hin zum optionalen „B-Staging“ des sich ergebenden Halbzeugs. Mit diesem zukunftsweisenden, klimafreundlichen Verfahren, das sich hervorragend in das mittlerweile unverzichtbare, interdisziplinäre Forschungsfeld der Circular Economy einfügt, bietet die Technologie eine adaptierbare Schlüsseltechnologie für industrielle Hochleistungsanwendungen