bluuebunny/crossref_metadata_2025 huggingface dataset:
De raptos y mujeres en la colonia cordobesa ¿Un adulterio encubierto?
Authors: Grana Romina
Published: July 2017

En este trabajo se ofrece la transcripción de un expediente sustanciado en Córdoba del Tucumán en el siglo XVII por rapto / robo de mujeres. La causa llama la atención por los modos en que se construye el delito; las versiones son varias pero el común denominador se vincula, por un lado, con el honor del marido ofendido y, por otro, con la responsabilidad de las mujeres casadas; ambos son los lugares donde se ancla la sensibilidad social. El pleito también ilumina cuestiones vinculadas a la traición entre pares, pues es el raptor quien se aprovecha de la confianza del hombre de la casa para robar a su mujer. El documento se conserva en el Archivo Histórico de la Provincia de Córdoba y su abordaje puede hacerse desde varios puntos de vista, los cuales, sin duda, ofrecerán algunas aproximaciones parciales sobre los modos de experimentar las transgresiones sociales en la sociorregión de la Córdoba colonial.
El feminismocomunitario: la creación de un pensamiento propio
Authors: Paredes Julieta
Published: July 2017

El texto realiza una explicación del feminismocomunitario como una propuesta surgida originalmente de debates al interior de la comunidad Mujeres Creando, en el marco de la insurrección del pueblo boliviano en el 2003. El feminismocomunitario inicia un camino de descolonización del feminismo que originalmente se plasmó en el libro Hilando Fino. Reconceptualizamos conceptos como feminismo y patriarcado, así como su utilidad para las luchas de nuestros pueblos. También dejaremos claras las diferencias de nuestras raíces de pensamiento, conocimiento y práctica social para poder hablar de la creación de un pensamiento propio.
Battlestar Galactica: A Closed-System Fictional World
Authors: Favard Florent
Published: July 2017

Cet article s’intéresse à la façon dont la série de science-fiction Battlestar Galactica (Syfy, 2003-2009) déploie un monde fictionnel que l’on peut concevoir comme centré sur un « système fermé », la Flotte coloniale. Il explore la façon dont la série maintient de manière explicite une crise perpétuelle au sein d’un univers conçu comme vaste et désert, sans autre force antagoniste que les Cylons. L’évolution de l’allure générale de la Flotte, point nodal des plans d’ensemble qui rythment les épisodes, est un aspect saillant de l’esthétique de l’entropie développée par la série, de même que son usage du décompte des survivants. L’article se conclut par une analyse des répercussions de ce système fermé au niveau thématique, et la tension entre la « prison » physique qu’est la Flotte et les rêves, visions et expériences divines des personnages.
Caprica, l’utopisme technologique et le « cyborg spirituel »
Authors: Achouche Mehdi
Published: July 2017

Cet article étudie la série de science-fiction Caprica sous l’angle des utopismes technologiques qui y sont représentés. Il examine plus particulièrement la conception mécaniste et dualiste du corps et de la conscience telle que représentée dans la série, qui imagine la naissance d’une intelligence artificielle d’un nouveau type et explore le rêve de l’immortalité digitale. La série souligne ainsi l’importance de l’aspiration spirituelle et du gnosticisme dans les techno-utopismes en général et dans le transhumanisme en particulier, s’éloignant progressivement des termes traditionnels du débat opposant le naturel à l’artificiel ou le matérialisme au spirituel.
Le cylon est-il un humain en souffrance ?
Authors: Lévy Ophir
Published: July 2017

Cet article interroge la faculté des cylons à connaître l’expérience humaine de la douleur, et pour être tout à fait précis, de la souffrance, c’est-à-dire la douleur physique en tant qu’elle est ressaisie par la conscience. Il s’appuie sur un épisode de la première saison de Battlestar Galactica intitulé « Flesh and Bone », traduit en français par « De chair et de sang ». Dans cet épisode, un cylon prénommé Leoben, qui s’était préalablement infiltré dans la flotte, vient d’être arrêté. Le commandant Adama demande à Kara Thrace, dite Starbuck, de l’interroger. Or, l’interrogatoire vire rapidement à la séance de torture. S’ensuit alors une discussion entre Starbuck et Leoben, au sujet de la souffrance comme expérience primordiale de l’existence humaine, qui nous amène à formuler avec eux plusieurs questions : dans quelle mesure la souffrance dévoile-t-elle ce qu’il y a d’humain en l’homme ? Dans quelle mesure un cylon qui connaît la souffrance fait-il cap en direction d’un horizon d’humanité ?
Caprica, l’esquisse d’un avenir sans lendemain
Authors: Lifschutz Vladimir
Published: July 2017

Cet article propose de s’intéresser à un exemple de fin de série spécifique. Avec l’épisode final de Caprica, nous choisissons de nous interroger sur une fin sans réelle conclusion anticipée, résolution saisonnière pensée comme une ouverture à une suite qui ne verra finalement jamais le jour. Malgré tout, les auteurs semblent avoir investi cette fin d’une véritable proposition. Entre le dénouement narratif et l’esquisse d’un avenir illusoire, Caprica aborde frontalement les conséquences de son annulation en plongeant les téléspectateurs dans cinq dernières minutes intenses et cathartiques, en forme de symphonie narrative – une apothéose finale, comme le laisse à penser le titre de l’épisode.
Investigation of Mechanical Properties and Dry Sliding Wear Behaviour of Graphite Reinforced Al7068 Alloy
Authors: Sajjan Basavaraj , Avinash L. , Varun S. , Varun Kumar K.N. , Parthasarathy Adithya
Published: July 2017

The aim is to study the mechanical property and dry sliding wear behaviour of Al7068/graphite composite with various weight fractions (5%, 10%, 15%) were prepared by liquid metallurgy route was investigated. The average particle size of graphite is 40 μm. In addition, Al7068 alloys were cast for comparison purposes. The alloys and composites were given a T6 heat treatment process (solution treatment at 540 oC, water quenching at room temperature and artificial ageing at 170 oC) .Microstructure, hardness and tensile properties of these composites were evaluated and compared with as-cast alloy and the composites without T6 heat treatment. In addition, tribological properties of these composites were evaluated using a Pin-on-Disc apparatus with different parameters (constant velocity of 2m/s and varying loads as follows 10N, 15N, 20N, 25N, 30N) .The microstructure of the composites shows homogenous distribution of graphite particles in the Al matrix except in the Al7068/15% graphite composite. The wear and mechanical properties of composites improve with increasing the weight fraction of graphite upto 10% and then decreases gradually. This study provides an alternative way to enhance the tribological behaviour of Al7068/graphite composite. The study also highlights the different contribution of different input process parameters (like: composition of Al-graphite, molding technique and particle size of reinforcement material) on wear properties of Al-graphite MMCs.
Optimization of Cutting Parameters in Machining GFRP Using End Mill Cutter through DoE and Verification through Genetic Algorithm
Authors: Sankar Shanmugasundaram , Manivarma V. Kumaresan
Published: July 2017

This article discusses optimization of critical parameters such as cutting speed, feed, depth of cut and method of machining while machining Glass Fiber Reinforced Plastic (GFRP) in vertical machining center using standard end mill cutter made up of High Speed Steel (HSS) for lesser cutting load, maximum material removal rate for better surface finish and dimensional accuracy through design of experiments. In composite material machining, surface finish is the critical deciding factor in determining surface quality. In this study, as per Taguchi’s L9 orthogonal array, predictable and unpredictable parts are followed to evaluate the consequence of cutting parameters on the machined component. The study includes surface roughness measurement using surface profilometer continued by physical measurement of machined pocket dimension. The experimental results, suggest suitable machining parameters in order to achieve the above target goal. In addition, C++ program is developed to cross check the most favorable machining parameters for maximum material removal rate using genetic algorithm. It is inferred from the study that the genetic algorithm results coincides very closely with the result given by the method of design of experiments.
Enhancement of Performance of Solar Parabolic Trough Collector Using Selective Absorption Coating
Authors: Sukanta Anbu Manimaran , Vignesh M. , Dhineshkumar C.
Published: July 2017

An alteration in the energy source is demanded which leads us to more efficient ways in sequestering solar energy using concentrating thermal collectors. This work is mainly performed to investigate and analyse the usage of selective absorption coating on the inner and outer walls of the absorber tube of a solar parabolic trough collector. This paper also analyses the changes in performance when using forced circulation for controlling the flow of working fluid through the absorber tube by using fans and pump and increasing the contact surface. The efficiency of the system was found to be around 55% and an increase in the efficiency of around 10 % was observed.
A Comparative Analysis and Effect of Water Depth on the Performance of Single Slope Basin Type Passive Solar Still Coupled with Flat Plate Collector and Evacuated Tube Collector
Authors: Balamurugan Samraj , Sundaram N. Shanmuga , Marimuthu K. Prakash , Devaraj J.
Published: July 2017

Many experimental and numerical works have been done on different configurations of solar stills to optimize the design by investigative the effect of climatic, operational and design parameters on its performance. One of the most important of the operational parameters that has received a considerable attention in the literature is the brine depth. A study was subsequently conducted to verify this trend by an experimental investigation on three types of solar still that was fabricated with an area of 1 m2 and tested in the composite climate of Coimbatore, Tamilnadu, India, (Latitude: 11°N; Longitude; 77°E and an altitude of 409 m above sea level) with five different brine depths, namely 1, 4, 6, 8 and 10 cm. The present study clearly validated that the decreasing trend in productivity with the increase of brine depth.
Optimization of Spur Gear Design to Reduce Stress
Authors: Senthil Kumar Mouleeswaran , Santhosh M. , Arvind E. , Ashwin M. , Prashant S.
Published: July 2017

The objective of the study is to reduce the stress created in the root fillet region as the maximum stress concentration in gears occurs in the fillet. Therefore, stress relieving features have been created at an offset distance from the root fillet to reduce the stress. A Spur gear with involute profile is taken for the study. The application taken for the study is the gear used in terrain vehicles. The material of the gear is EN-353 grade Steel. Based on the compressive strengths and bending strengths, the spur gear is designed to the required application. The gear is modelled using the specifications obtained from the design calculations. The forces acting on the gear is calculated considering the application in which it is used. The gear is then analysed using the ANSYS WORKBENCH 14.0 software. It has been found that the maximum stress acts near the root fillet region. Hence, stress relieving features of circular and elliptical shapes are created at an offset distance from the root fillet. It has been found that the gear with elliptical stress relieving hole has the minimum stress than those of gears with other combinations. The next objective which is to reduce the mass of the gear is done by creating larger holes in the lower stress regions of the gear. The mass reducing features are created in the gears with stress relieving features and each gear has been subjected to analysis for the minimum amount of stress. It has been found that the value of stress is less in the gear with mass reducing holes but with no stress relieving feature. Thus, the stress acting on the root fillet region has been reduced by 20% by creating circular and elliptical holes. The other objective of mass reduction is satisfied by creating larger holes.
Development of Environmental Value Stream Model for Assessing Sustainability in Manufacturing
Authors: Jayakrishna Kandasamy , Srikrishna M. , Senthilkumar S. , Vinoth Louie A. , Kamalakannan R.
Published: July 2017

Increasing concern over the resource consumption and utilisation alongside of any manufacturing process decides the sustainability of the product. Many contemporary organisations due to stringent government regulation and policies now focus on management of waste generated across their units. Value Stream Mapping (VSM) generally focuses on reducing task time and thereby reducing monetary over heads. From the environmental perspective, the type of waste produced is important because of the difference in level of toxicity and environmental impact. This work focuses on imbibing environmental waste into the lean method of value stream mapping. The proposed integrated model was implemented in a case organisation and environmental impact was computed. The developed model can be used by stake holders and represent environmental impact at individual process and product levels to align organisation practices with strategic objectives for waste reduction.
Development and Characterization of Mg-SiC Nanocomposite Powders Synthesized by Mechanical Milling
Authors: Penther Daniela , Fleck Claudia , Ghasemi Alireza , Riedel Ralf , Kamrani Sepideh
Published: July 2017

Magnesium powder in micron scale and various volume fractions of SiC particles with an average diameter of 50 nm were co-milled by a high energy planetary ball mill for up to 25 h to produce Mg-SiC nanocomposite powders. The milled Mg-SiC nanocomposite powders were characterized by scanning electron microscopy (SEM) and laser particle size analysis (PSA) to study morphological evolutions. Furthermore, XRD, TEM, EDAX and SEM analyses were performed to investigate the microstructure of the magnesium matrix and distribution of SiC-reinforcement. It was shown that with addition of and increase in SiC nanoparticle content, finer particles with narrower size distribution are obtained after mechanical milling. The morphology of these particles also became more equiaxed at shorter milling times. The microstructural observation revealed that the milling process ensured uniform distribution of SiC nanoparticles in the magnesium matrix even with a high volume fraction, up to 10 vol%.
Ultrasonic-Impregnation for Fiber-Reinforced Thermoplastic Prepreg Production
Authors: Sockol Steve , Doerffel Christoph , Mehnert Juliane , Zwinzscher Gerd , Rein Steffen , Spieler Mirko , Kroll Lothar , Nendel Wolfgang
Published: July 2017

Fiber-reinforced thermoplastics have a high potential for big scale light weight process applications due to low processing times and recyclability. Further advantages are the low emissions during the manufacturing process and beneficial handling and storing properties of the semi finished materials.
Thermoplastic composites are made of reinforcement fibers and a thermoplastic polymer matrix by applying two essential sub processes:
(1) melting of the matrix-material and
(2) impregnating the textile component with molten matrix-material.
At present state of art both sub-processes are applied by using double-belt-presses, characterized by high processing temperatures and high processing forces. Therefore, a large amount of energy is needed to create the necessarily high compaction forces and temperatures with hydraulic cylinders and electric heating. Convection, infrared-radiation and the cooling (dynamic) of tempered machine parts leads to a significant dissipation of energy. Especially the process for generating the hydraulic pressure has a low level of efficiency. Therefore, in respect to economic and ecologic reasons, novel energy-efficient impregnation processes need to be investigated and developed.
The represented novel impregnation process is based on ultrasonic technology. A stack of polymer film (outer layers) and a textile ply (inner layer) is formed and the energy is applied with an ultrasonic sonotrode. The efficient, fast and strongly concentrated energy application into the thermoplastic films allows the development of novel and highly flexible machine concepts. These can be used for development of small scale up to large scale production processes. The ultrasonic-technology allows a continuous impregnation of the textile component with molten matrix-material.
A custom-designed prototype was developed. First material samples were produced and the technological parameters studied. A characterization of the experimental results, material samples, prototype machine and process is the focus of this paper.
The Development of Lead-Free Sliding Contacts Based on Bronze-Graphite Composites through Powder Injection Moulding
Authors: Ahmad Husam , Stelzer Robert , Nestler Daisy , Nendel Wolfgang , Kroll Lothar , Wagner Guntram
Published: July 2017

Sliding electrical contacts are traditionally produced by conventional compacting technologies. Employing the powder injection moulding process (PIM) as a new manufacturing method can offer several advantages such as the fabrication of complex net-shaped parts, cost-effectiveness and high volume productions. The PIM process route consists of the following steps: powder processing, compounding, injection molding, debinding and sintering. A two-stage process consisting of solvent debinding and thermal debinding is often used to remove the moulding binder. In the present paper, the suitability of the powder metallurgical processes: mechanical alloying and powder mixing for the preparation of bronze-graphite powder mixtures for the compounding and injection moulding of sliding contacts is discussed. The use of a suitable binder is of central importance for the preparation of injection-moldable feedstocks. For this purpose, two commercial ready-to-use binder systems were utilized and evaluated. The essential challenge of the process route is to optimize all parameters of the subprocesses to achieve a damage-free debinding and sintering of the injection-moulded parts. First results on the influence of the graphite content, the binder fraction, the debinding and sintering parameters are presented and discussed.
Characterization and Simulation of Bending Properties of Continuous Fiber Reinforced C/C-SiC Sandwich Structures
Authors: Shi Yuan , Heidenreich Bernhard , Dileep Pranav Kumar , Koch Dietmar
Published: July 2017

At the Institute of Structures and Design of German Aerospace Center (DLR) in Stuttgart, C/C-SiC sandwich structures based on continuous fiber reinforced folded cores and skin panels have been developed via Liquid Silicon Infiltration (LSI) and in situ joining method. The resulting lightweight structures offer a high potential in various application areas such as optical benches of satellites or charging racks for high temperature furnaces.A major impediment for the new development and practical application of ceramic sandwich structures is the lack of know-how of characterization and simulation of their mechanical properties. In this study, several types of C/C-SiC sandwich structures with folded cores with different fiber orientations (0°/90° and ±45°) in the core structure were manufactured and mechanically tested in four point bending. The mechanical properties of the different sandwich structures were correlated to analytical calculation and numerical (finite element) simulation. The comparison showed good correlation. The proposed evaluation methods are suitable to determine and simulate the mechanical properties of C/C-SiC sandwich structures and are a versatile tool for further product development.
Manufacturing and Properties of Tungsten Carbide-Oxide Composites
Authors: Vornberger Anne , Pötschke Johannes , Berger Christian
Published: July 2017

Conventional WC-Co hardmetals are widely used in various applications due to their excellent properties. High hardness can be achieved using compositions with little to no content of cobalt or nickel. These binder metals are hazardous to health, making a substitution not only desirable because of availability and cost reasons. A new possibility to manufacture such hard materials is the combination of tungsten carbide with oxides such as Al2O3 and ZrO2. In this way the binder metal content can be replaced. Furthermore the content of the also expensive WC can be reduced. Such metal carbide – oxide composites with oxide contents between 16 vol% and 40 vol% were manufactured. The completely dense composites feature high hardness values of 2000 HV10 to 2400 HV10 while also having an acceptable fracture toughness of up to 7 MPa⋅m1/2. The improved mechanical properties make the replacement of WC-Co hardmetals and binder free WC ceramics in special areas possible.
How to Tame the Aggressiveness of Liquid Silicon in the LSI Process
Authors: Mainzer Bernd , Kelm Klemens , Watermeyer Philipp , Frieß Martin , Koch Dietmar
Published: July 2017

Liquid Silicon Infiltration (LSI) is a technique to manufacture non-oxide ceramic matrix composites such as C/C-SiC or SiC/SiC. In the beginning of this three-step process, fiber preforms are shaped and impregnated with phenolic resins. After curing, the preforms are pyrolyzed to convert the polymer matrix to a porous carbon matrix. This porosity is then used to infiltrate liquid silicon by capillary forces. Simultaneously, an exothermic reaction of silicon and carbon creates a silicon carbide matrix. Generally the liquid silicon reacts with any carbon and even with SiC present in the form of fibers, fiber coatings or matrix. Therefore, especially the fibers must be protected from Si attack effectively. The morphology of silicon carbide was observed to be heavily driven by Ostwald ripening. This can be suppressed by the addition of boron to the melt. The initially formed SiC crystals in C/C-SiC composites are hereby prevented from grain coarsening, resulting in almost completely preserved C/C blocks. For the manufacture of SiC/SiC composites, the silicon boron alloys allow an effective preservation of the nanocrystalline SiC-fibers. Thus, the use of Si based B containing alloys helps effectively to moderate and control the aggressive reaction during LSI process.
Use of Recycled Waste Paper as Fiber Reinforcement for Polypropylene - Examination of Mechanical Properties in Comparison to NFRP
Authors: Scholten Andrea , Plogmann Niklas , Meiners Dieter
Published: July 2017

During recycling of waste paper from private households different fractions containing plastics and polluted paper fibers are received. Those polluted fibers cannot be recycled in the common paper manufacturing process or for energy recovery like in waste incinerating plants due t o economic reasons. Current research at the Institute of Polymer Materials and Plastics Engineering at Clausthal University of Technology evaluated the use of this waste paper recyclate as a substitution for natural fibers as fillers and reinforcements in polypropylene. Special attention was given to the mechanical properties of the composites. Additionally the influence of maleic anhydride grafted polypropylene (MAPP) as an adhesive was investigated.
Optimization of Corrosive Properties of Carbon Fiber Reinforced Aluminum Laminates due to Integration of an Elastomer Interlayer
Authors: Stoll Matthias , Stemmer Franziska , Ilinzeer Sergej , Weidenmann Kay André
Published: July 2017

Fiber-Metal-Laminates (FML) show superior dynamic mechanical properties combined with low densities. The mechanical performance of for example commercially available fiber-metal-laminate, glass laminate aluminum reinforced epoxy, can be improved by the substitution of glass fibers with carbon fibers. However, carbon fiber reinforced aluminum laminate introduces a mismatch of coefficients of thermal expansion and the possibility of galvanic corrosion. The fiber-metal-laminate is altered by the integration of an elastomer interlayer which is desired to solve both problems. The high electrical resistance is supposed to inhibit the corrosion. This study focuses on the effect of galvanic corrosion caused by neutral salt spray tests on fiber-metal-laminates, the influence of an elastomer interlayer and the quantification of the residual mechanical properties. The galvanic corrosion affects the interfaces of the laminates, therefore in this study edge shear tests and flexural tests were carried out to quantify the residual properties and thereby the corrosive damage.
The elastomer interlayer was found to inhibit galvanic corrosion in the salt spray chamber, whereas the fiber-metal-laminate without interlayer showed corrosive damage. Furthermore, the mechanical properties of the fiber-metal-laminate with elastomer interlayer remained constant after the corrosion tests, whilst the fiber-metal-laminate’s properties decreased with corrosive loads.
Micro-/Mesoporous Polymer-Derived Ceramic Structures Using Molecular Porogens
Authors: Konegger Thomas , Peterlik Herwig , Bordia Rajendra K.
Published: July 2017

Micro-and mesoporous ceramics demonstrate promising properties for applications in energy-and environment-related fields. Due to their high thermal and chemical stability, they are particularly suited for separation in harsh thermal or chemical environments, e.g. as membrane materials for the separation of gas mixtures. In this work, we present the use of a preceramic poly(vinyl)silazane in combination with organic molecular porogens for the generation of micro-/mesoporous non-oxide ceramic structures. Microporosity is generated during the pyrolytic conversion process, while the addition of molecular porogens, to be removed during the heat-treatment, enables further control of the micro-/mesopore structure. A systematic investigation of various porogens showed the suitability of polystyrene for this purpose. Based on these findings, the pore structure and pore connectivity of polysilazane/polystyrene-derived structures were evaluated using gas physisorption and small angle X-ray scattering techniques. This material was further investigated by preparing asymmetric membranes consisting of micro-/mesoporous polysilazane/polystyrene-derived layers on porous ZrO2/TiO2 supports. The potential for gas separation applications was then demonstrated by single-gas permance evaluation of the generated structures at temperatures up to 300 °C.
TFP Reinforced Metal - One Way to Increase the Specific Strength
Authors: Hutsch Thomas , Aßmann Fabian , Weißgärber Thomas , Kieback Bernd
Published: July 2017

The integration of fibers, especially tailor fiber placement (TFP), in metal matrices offers one way to generate composite materials with increased specific strength compared to the unreinforced metal matrix. The TFP can be adapted according to the final load paths through the component and can be covered partially or fully with the metal. Following this approach load transfer elements can be built, transferring much load and having low mass. First fields of application are identified in building and automotive industry. This work includes the powder metallurgical manufacturing process using Spark Plasma Sintering (SPS) technique, the characterization of the microstructure and the tensile test of different specimens (sintered copper, TFP (as received) and TFP (Cu covered) reinforced copper). Experimental result on 19.5 vol.% TFP (Cu covered) reinforced copper shows an increase of specific strength around a factor of 2.2 compared to pure copper.
Mechanical Behavior of Loops with Small Diameters
Authors: Lang Anna , Focke Oliver , Herrmann Axel S.
Published: July 2017

To meet the comprehensive requirements of lightweight design, a material minded design method will be aimed. A fiber minded solution for load application in fiber reinforced plastics are loop joints, which are mainly applied for introducing high concentrated tensile loads, e.g. in mountings for rotor blades, or in pre-tensioned supporting structures. Usually, these loop joints consist of, diameters in centimeter scale. Miniaturized loop joints with diameters in millimeter scale are applied in transition structures for carbon reinforced plastic-aluminum multi material designs. Factors of miniaturization influencing the mechanical behavior are decoupled for tensile testing. Data from computer tomography provides information on the failure behavior of loop joints. To validate the non-destructive test method microsections will be used.
Anodic Oxidation of Carbon Fiber Surfaces: Influence of Static and Dynamic Process Conditions
Authors: Moosburger-Will Judith , Bauer Matthias , Schubert Fabian , Cheick Jumaa Omar , Horn Siegfried R.
Published: July 2017

We investigate the effects of static and dynamic anodic oxidation treatment on the surface chemical composition and functionality of carbon fibers. During static treatment, the electrolytic surface oxidation process is performed on a spatially fixed carbon fiber bundle, while in the dynamic process a moving, continuous carbon fiber tow is oxidized. In both treatment modes electrolytic current density and treatment time were varied. Surface chemical composition and functionality of the resulting carbon fibers were analyzed by x-ray photoelectron spectroscopy. A good agreement between the chemical composition and the functionality of fibers from static and dynamic anodic oxidation treatment is found. This suggests that results from static fiber treatment in a variable, easy to handle laboratory setup can be applied to dynamic anodic oxidation process conditions on a large scale.
Surface Characterization of Carbon Fibers by Atomic Force Microscopy: Roughness Quantification by Power Spectral Density
Authors: Brück Bastian , Guglhoer Thomas , Haug Simon , Kunzmann Christina , Schulz Michael , Schneck Tanja , Spoerl Johanna , Buchmeiser Michael R. , Horn Siegfried R. , Mueller Wolfgang M.
Published: July 2017

The topography of a surface consists of structures of different length scales. The surface roughness caused by these structures plays a decisive role in interfacial properties. Atomic Force Microscopy (AFM) can be applied to measure the surface topography with great accuracy and thus facilitates roughness quantification. Here, however, the data reduction poses a challenge. In a conventional approach, surface roughness parameters are evaluated based on averaging height differences, which leads to values dominated by the largest height differences of the surface topography. To quantify contributions of smaller structures to the roughness, a previous study presented a tunable local background correction, which eliminates structures on a larger than selected scale. Therefore, this method only considers surface structures smaller than the chosen scale. A different approach to quantify surface roughness on all length scales covered by AFM measurements uses Fourier transformation of the surface topography to calculate the power spectral density, which describes the amplitudes of different contributing spatial frequencies.In the current study, a new approach based on power spectral density is used to quantify surface roughness parameters as a function of the length scale of contributions to the surface topography. This procedure allows a comprehensive characterization of surface roughness and an intuitive comparison of different surfaces.The usefulness of this method and its compatibility to local background correction is demonstrated by analyzing several commercially available carbon fibers with and without different fiber surface treatments.
Analysis of the Effects of Raster Orientation in Components Consisting of Short Glass Fibre Reinforced ABS of Different Fibre Volume Fraction Produced by Additive Manufacturing
Authors: Heuer Anselm , Pinter Pascal , Weidenmann Kay André
Published: July 2017

Additive manufacturing provides the ability to produce structural components featuring complex shapes in one step, compared to traditional methods of production. Therefore, additive manufacturing has recently gained attention for the direct production of parts. Using fibre reinforced filaments offers the opportunity to improve the mechanical properties of FFF printed components. In order to dimension them correctly, the mechanical properties of additive manufactured samples based on glass fibre reinforced filaments were determined. Additionally, the influence of extrusion paths resulting in a distinct fibre orientation were taken into account. Samples were produces by FFF-method (Fused Filament Fabrication) from three materials: Bulk ABS and short glass fibre reinforced ABS featuring 5 wt% and 10 wt% fibre content. Additionally, samples were printed in two different raster orientations of 0° and 90°. Three different sample types were manufactured in order to perform tension, flexural and impact tests. Prior to printing the samples, the slicer parameters were optimized for usage with the fibre reinforced filament. To determine the FOD (Fibre Orientation Distribution) and FLD (Fibre Length Distribution), the samples were scanned using a CT. Results show that fibre reinforced filaments used in this contribution can increase stiffness to 150 % of the bulk material in printing direction with a fibre weight content of 10 %. CT investigations have shown that the orientation of fibres is primary aligned to the printing path.
In-Line Integration of Sensors in Thermoplastic Composite Structures Using Novel Continuous Orbital Winding Technology
Authors: Decker Ricardo , Arnold Benjamin , Wallasch Rainer , Bauer Angelika , Tirschmann Ramon , Mehner Jan , Nendel Wolfgang , Kroll Lothar
Published: July 2017

Currently there is a great demand for energy and resource efficient and also function integrating manufacturing processes. Therefore, suitable technologies and corresponding foundational researches are being pursued in the federal cluster of excellence “MERGE Technologies for Multifunctional Lightweight Structures” at the Technische Universität Chemnitz. A part of this project is the development of the continuous orbital winding (COW) technology including the goal of a large-scale process used for special fiber-reinforced thermoplastic semi-finished products. This method is an inverted winding process. The winding core needs to perform only the feed motion. Furthermore, this allows synchronization to upstream and downstream process chains.Due to the modular structure of the machine concept, it is possible to integrate a sensor system during production without interrupting the process. For this purpose, a textile carrier tape with integrated electrically conductive fibers and applied sensors is embedded. Various silicon sensors, e.g. acceleration, pressure or stress sensors are applied by micro-injection molding. A so-called “interposer” is used as an electrically adapter between the microstructures of the sensor system and the mesostructures of the textile.In this article, basic investigations for the continuous processing of semi-finished thermoplastic structures and the integration of sensors are presented. It is intended to determine the bonding properties, possible structural thickening by the sensors and the resistance of the sensor systems and its electronic components to the process conditions.In summary, investigations are carried out to determine the parameters of the machine system as well as to determine the optimum processing conditions for the application of additional elements.
Properties of Second Life Carbon Fibre Reinforced Polymers
Authors: Manis Frank , Schmieg Maren , Sauer Michael , Drechsler Klaus
Published: July 2017

In this study different materials made out of cut-off as well as reclained carbon fibres (rCF) are described and compared. For this benchmark nonwovens, compounds, SMC, BMC, as well as standard lightweight materials like high alloy steels, aluminium and magnesium are taken into account. Specific mechanical properties like modulus and tensile strength are used to show the lightweight potential of recycled carbon fibre materials in ashby charts. It is shown that rCF products can substitute glass fibre applications and are also comparable to metals and alloys.
Development of Thermoplastic Composites for Visible Parts in Automotive
Authors: Köhler Thomas , Vonberg Klaus , Mohr Benjamin , Gries Thomas , Seide Gunnar
Published: July 2017

In order to reduce CO2 emissions, for the automotive industry, the most promising area of research is lightweight construction. Next to weight reduction, lightweight materials like fiber reinforced thermoplastic composites (FRTC) may also improve mechanical properties of vehicle body parts. FRTCs, so-called organic sheets, have the potential for large scale series production and they can be back moulded due to the thermoplastic matrix. On the other hand high production cycle times and a poor surface quality are limiting their potential. Therefore, ITA’s current research approaches these problems in two ways. Nanomodified materials and a new tool concept for heat pressing are going hand in hand and may lead to the technology’s breakthrough.To reduce the cycle times of the production of FRTCs innovative and modified matrix systems are investigated. The goal of the public founded project “VarioOrgano” is to analyze the potential of these modified yarns and the tool system during the FRTC production. Moreover, the capability of these composites in visible parts in automotive applications is investigated. Therefore, the whole process chain from compounding, to melt spinning, commingling and consolidation with a heat press is investigated.This paper shows the production steps along the process chain to produce these FRTCs with focus on hybrid yarn development and production.
Research of the Load Bearing Capacity of Shape-Optimized Metal Inserts Embedded in CFRP under Different Types of Stresses
Authors: Pottmeyer Florentin , Muth Markus , Weidenmann Kay André
Published: July 2017

An efficient implementation of lightweight design is the use of continuous carbon fiber reinforced plastics (CFRP) due to their outstanding specific mechanical properties. Embedded metal elements, so-called inserts, can be used to join metal-based attachments to structural CFRP parts in the context of multi-material design. They differ from other mechanical fasteners and have distinctive benefits. In particular, drilling of the components to be joined can be avoided and, depending on the preforming, fiber continuity can be maintained using such elements. Thus, no local bearing stress is anticipated. Previous work published by the authors [1] dealt with a systematic research of the influence of different types of stresses on the load bearing capacity of welded inserts. This contribution aims at the investigation of the performance of shape-optimized inserts under the same types of loading to compare with the results of the welded inserts serving as a reference. For that purpose, the respective load bearing capacities were evaluated after preinduced damages from impact tests and thermal cycling. In addition, dynamic high-speed tensile tests (pull-out) were conducted under different loading velocities. It is shown that the load bearing capacities increased up to 19% for high velocities (250 mm/s) in comparison to quasi-static loading conditions (1.5 mm/min) showing an obvious strain rate dependency of the CFRP. Quasi-static residual strength measurements under tensile loading identified the influence of the respective preinduced damages of the insert. Influence of the thermal loading condition was evaluated by placing the specimens in a climate chamber and exposing it to various numbers of temperature cycles from-40 °C to +80 °C with a duration time of 1.5 hours each. Here, it turned out that already 10 temperature cycles decreased the quasi-static load bearing capacity up to 31%. According to DIN EN 6038 the specimens were loaded with different impact energies and the residual strength were measured carrying out pull-out tests. It could be shown that the damage tolerance is significantly lower for the shape-optimized insert due to failure-critical delamination. The optimized insert also endured lower impact energies and the influence on the performance was higher.
Tailored Inserts Based on Continuous Fibre for Local Bearing Reinforcement of Short Fibre Thermoplastic Components
Authors: Arnaut Katharina , Herrmann Axel S.
Published: July 2017

The injection molding process is an economical process for manufacturing of thermoplastic components. Complex geometries can be realized with high automation and short cycle times. However the mechanical properties of injection-molded parts are not suitable for mechanical demanding components even by adding short or long fibre. As bold connections are used frequently for load transfer, the load introduction area particularly is limited by low bearing strength. The present paper shows the influence of tailored inserts based on continuous fibre on the bolt-loaded hole of injected test specimen.
Bioproducts from the Slow and Fast Pyrolysis of Sugar Cane Bagasse
Authors: Borges Bruno Aurélio Francisco , Urias Patrícia Moisés , Barrozo Marcos A.S. , dos Santos Kássia Graciele
Published: July 2017

In this work, it was done a series of analysis in different conditions of the pyrolysis process to verify the difference of the composition in each one of the final products. In the case of the slow pyrolysis the heating ratio varied among 1.5, 20, 40 e 50 °C/min, and analyzed for each of these rates the composition of the final product. For the case of the fast pyrolysis, the temperature varied among 350, 400, 450, 500, 550 °C, maintaining the other conditions of the process constant, in the end of the process analyzed the composition of the final product for each temperature. For the verification of the composition of these products, they were classified and separate in categories according to the functional group, and after that, the ones who had the most relevant quantities were more deeply analyses to verify some important characteristics and the main industry applications. After this, it was determined the ideals conditions of slow and fast pyrolysis. The resulting products were analyzed by gas chromatography/mass spectrometry. For slow pyrolysis, the heating rate of 40°C/min produced a diversified product, composed by the heterocyclics, levoglucosan, phenols and hydrocarbons. The fast pyrolysis produced mainly the heterocyclic compounds, levoglucosan, phenols and carboxylic acids, in temperatures between 450°C and 500°C.
Synthesis by High-Energy Ball Milling of MgH2-TiFe Composites for Hydrogen Storage
Authors: Neto Ricardo Mendes Leal , de Araújo Silva Rafael , Floriano Ricardo , Coutinho Graziele Cristina Seco , Falcão Railson Bolsoni , Leiva Daniel Rodrigo , Botta Filho Walter José
Published: July 2017

The aim of this work is to investigate the influence of some processes variables on the microstructure and hydrogen absorption kinetics of MgH2 - X wt.% TiFe composites. Samples were synthesized by high-energy ball milling in a planetary (X = 40, 50, 60) and shaker mill (X = 40) under high-purity argon atmosphere. Commercial MgH2 instead of Mg powder was used in order to reduce adherence on the vial and balls. TiFe powder was previously produced by ball milling a mixture of TiH2 and Fe powders followed by a reaction synthesis at 600oC. Milled composites samples were characterized by XRD and SEM analysis. Milling time was preliminary investigated (X = 40) in the planetary ball mill (6 to 36h). TiFe particle size reduction was shown to be difficult since they are surrounded by MgH2 matrix. Strong particle reduction was obtained by using a shaker mill only for 2 hours and adding cyclohexane as process control agent. No reaction between MgH2 and TiFe compound was observed in any milled sample. Hydrogen absorption kinetics measurements of the as-milled samples were conducted on an Sieverts' type apparatus at room temperature after hydrogen desorption at 350oC under vacuum. The best hydrogen kinetics (3 wt% at the first hour) was attained by the planetary milled sample (36 h). Higher hydrogen capacity was observed for the sample milled in the shaker mill (4.0 wt.%), but only after 13h.
Development of Ti-12Mo-8Nb Alloy for Biomedical Application
Authors: Borborema Sinara Gabriel , da Silva Kassya Jessica Peixoto , Jacinto Caroline Miranda , dos Santos Leizy Pâmela Oliveira , Nunes Carlos Angelo , Araújo Leonardo Sales , Dille Jean , Baldan Renato , de Almeida Luiz Henrique
Published: July 2017

Several beta titanium alloys were developed for biomedical applications due to the combination of low elasticity modulus, high strength, fatigue resistance and good ductility with excellent corrosion resistance. In this regard, a new metastable beta titanium Ti-12Mo-8Nb alloy was developed, as an alternative for the traditional Ti-6Al-4V alloy, with the substitution of vanadium and aluminum for molybdenum and niobium. The objective of this work was to present the microstructural characterization and mechanical properties of the Ti-12Mo-8Nb alloy, heat treated for 1h at 950oC under high vacuum and then water quenched. The microstructure of the alloy was characterized by X-ray diffraction and optical microscopy. Vickers microhardness and nanoindentation were performed for determination of hardness, Young’s modulus and the ratio of hardness to Young’s modulus. The Ti-12Mo-8Nb microstructure consisted of β phase and the values obtained for the ratio of hardness to Young’s modulus were higher than the Ti-6Al-4V alloy.
Zinc Oxide Nanoparticles as Antimicrobial Additive for Acrylic Paint
Authors: Fiori Jair J. , Silva Lucinao Luiz , Picolli K.C. , Ternus R. , Ilha J. , Decalton F. , Mello J.M.M. , Riella Humberto Gracher , Fiori Márcio Antônio
Published: July 2017

Currently the use of nanotechnology has been seeking to develop additives that have antimicrobial and low toxicity, enabling applications in various industrial sectors, in particular the paint industry. Inks with antimicrobial properties enable greater security to the user, eliminating pathogens that can cause disease when in contact with humans and animals. Thus, the zinc oxide nanoparticles have attracted a great scientific and technological interest as inorganic antimicrobial agent due to its oligodynamic effect. This work aims to study the effect oligodynamic zinc oxide nanoparticles in antimicrobial properties of acrylic paints. The acrylic paints were developed with various concentrations of zinc oxide nanoparticles, and were subsequently conducted microbiological characterization of death curve and agar diffusion. To evaluation the physico-chemical properties were used the techniques differential scanning calorimetry (DSC); Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results demonstrate that there was a reduction in the high antimicrobial activity of paints containing zinc oxide nanoparticles as compared to standard paint. Even with the addition of zinc oxide nanoparticles did not change the microstructure and chemical properties of acrylic coatings.