bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimum Gradation Direction for a Functionally Graded Endodontic Prefabricated Parallel Post: A Finite Element Method
Authors: Helal Wasim M.K. , Shi Dong Yan
Published: July 2015

The main purpose of the present work is to determine the optimum gradation direction of an endodontic prefabricated parallel post (EPPP) made of functionally graded material (FGM). To determine the optimum gradation direction of an EPPP made of FGM, the finite element method (FEM) is used. After that, the optimization technique was adopted in order to determine the optimum material gradient for the functionally graded endodontic prefabricated parallel post (FGEPPP). Simulation results indicated that, the optimum gradation direction for the FGEPPP is from up to down, and can be described by using a modified sigmoid function. The effect of varying of the material gradient indexes on the performance of the (FGEPPP) is investigated. Also, stress distributions in all of FGEPPP cases and in homogeneous EPPP case are investigated. The current investigation shows that, the use of the FGM improves the performance of an EPPP.
Thermal Increasing Information for Foot Surface during Jogging
Authors: Luo Yin , Tong Ying Juan , Hu Ying Ying
Published: July 2015

Thermography information of foot is playing very important role in body character and related products design. The purpose of this study is to investigate the distribution and change character of foot skin temperature variety during low-intensity movement. Totally 19 subjects participated in this testing, skin surface temperature monitor was using high-precision Infrared Thermal Imager. The average foot skin temperature existed a significant difference at rest condition. After 30min persistent low-intensity exercise, each area of the foot was increased, and the increasing trend was quite similar. This study could provide the basis of foot physiological function understanding.
Bimodal Particle Reinforcement for Wear Resistant Powder Metallurgy Steels
Authors: Gianessi Antonio , Gierl-Mayer Christian , Danninger Herbert
Published: July 2015

Reinforcement of powder metallurgy steels with fused tungsten carbide (FTC) has been shown to improve the wear resistance under certain loading conditions. A weakness is however the low hardness of the matrix, which results in selective wearing of the matrix between the carbide particles, i.e. “washing-out” effects. In the present study, in a first round fine metallic or carbidic particles were added to the iron-graphite powder mix, and the blends were die compacted and sintered in protective atmosphere. The specimens were then tested under different wear loads. It showed that also metallic powders added were transformed into carbides during sintering, thus resulting in reinforcement by fine carbides. Since Mo alloying proved to be most effective with regard to hardness and strength, specimens Fe-3%Mo-0.8%C reinforced with 20% coarse FTC (all in mass%) were sintered and tested according to ASTM G65, Continuous Impact Abrasion and dry sliding against ball bearing steel. It showed that Mo addition had quite pronounced positive effect on the G65 erosion resistance and, somewhat less, on dry sliding, while wear resistance in CIAT was less affected; the basic wear mechanisms however remained unchanged.
Bacterial Cellulose Reinforced Flax Fibre Composites: Effect of Nanocellulose Loading on Composite Properties
Authors: Fortea-Verdejo Marta , Bumbaris Elias , Lee Koon Yang , Bismarck Alexander
Published: July 2015

Loose hierarchical flax fibres/polypropylene composites were manufactured in a simple way based on a paper-making process in order to include nanocellulose and allow the hornification of the nanofibres in a controlled manner. The effect of flax fibre content on the flax/polypropylene composites and the influence of nanocellulose on the properties of these composites are discussed. By increasing the flax content a slight decrease of the tensile strength and an increase of the Young´s modulus were observed. On the other hand, no significant effect was noticed when increasing the bacterial cellulose content in the composites.
Novel Metal-Matrix Composites Prepared by Paper Manufacturing Technology
Authors: Wenzel Claudia , Aneziris Christos G.
Published: July 2015

The current contribution deals with metal-matrix composites prepared by paper manufacturing technology. In contrast to conventional techniques, this technology is an energy-and cost-efficient process for the shaping of thin sheets using solid powder mixtures. Conventional and pre-ceramic as well as pre-metallic paper-manufacturing have in common that cellulose (pulp) fibres are loaded with inorganic fillers. The present study is focused on the paper web formation using a metastable austenitic steel powder (16-7-3 %Cr-%Mn-%Ni) and a magnesia partially stabilised zirconia powder as inorganic fillers. The paper web formation was investigated. During filtration of the aqueous fibre-filler suspension the steel particles were incorporated in-between the fibre network and steel clusters were formed. Thus, solid retentions of > 90 wt.% were achieved. Calendering had a positive influence on porosity, bulk density, and tensile strength of the green paper sheets. The development of an optimized debinding process is presented and the microstructural changes as well as phase formations during firing are discussed in response to the residual carbon content. The sintered composites attained ultimate tensile strengths of up to 177 N/ mm2 at a total porosity of 66 %. These metal-matrix composites are promising materials for the shaping of light-weight structures.
Short Glass Fiber Reinforced PA6 Materials for Automotiv Applications – Assessment Aging Behavior with Methods of Polymer Diagnostics
Authors: Schoßig Marcus , Illing Thomas , Grellmann Wolfgang , Langer Beate
Published: July 2015

The qualitative and quantitative assessment of the aging behavior of polymers and polymeric products depends on a substantial characterization of the materials properties and is linked to a multi-parametric approach. However, the choice of suitable polymer diagnostics test methods as well as parameters for the characterization of the material behavior are important. The aging of products can be attributed to complex factors and due to the superposition of different factors, the generation of simple relationships is impossible. Important materials for the automotive industry are fiber-reinforced PA6 materials, which can fulfill the requirements related to the mechanical properties like stiffness, strength, toughness as well as other properties. However, the knowledge for the assessment of different climate conditions as well as media on the aging behavior of such materials is not complete. For this reason, it is essential to describe the behavior with a material-physical approach.
Fast Curing of Carbon Fiber Reinforced Plastics Using the Integration of Nanoparticles
Authors: Exner Wibke , Opitz Mark , Wierach Peter
Published: July 2015

Fast curing of carbon fiber reinforced plastics (CFRPs) is limited by the degradation of the resin under high temperatures and by the development of internal strains. The authors counter these problems by adding nanoparticles to the matrix of CFRPs. In the presented work various volume fractions of nanosized aluminum oxide particles are integrated into the epoxy resin RTM6. To demonstrate the increased heat flow within the CFRP component, thermal conductivity tests are presented. Results show increasing values as the filler content is raised.With increasing filler content the reaction speed is also accelerated. This effect is analyzed by differential scanning calorimetry. It is shown that the particle surface has a catalytic effect on the curing of the epoxy resin. The results of the author also show that the added nanoparticles not only change the material composition, but also modify the network of the epoxy resin. In a series of experiments it is demonstrated how nanoparticles decrease the chemical shrinkage. The results show a reduction of the shrinkage higher than the volume fraction of the nanoparticles, which can be explained by the formation of interphases. Thermal mechanical analysis also confirms a decreased thermal shrinkage due to the integration of nanoparticles. Finally, the inspection of L-shaped CFRPs samples with different filler contents show the ability of nanofillers to decrease the spring-in.In summary, the integration of aluminum oxide decreases the thermal as well as the chemical shrinkage, increases the thermal conductivity and accelerates the chemical reaction.Overall, these changes in curing behavior lead to an increased dimensional stability of the CFRPs. Thus, nanoparticles may be one way of overcoming the disadvantages of fast curing cycles.
Fundamental Studies and Development on an Innovative Ceramic/Polymer Material Compound
Authors: Nestler Daisy , Todt Andreas , Wielage Bernhard , Wagner Guntram
Published: July 2015

Fibre-reinforced ceramic composite materials offer excellent thermal, mechanical and chemical properties. Due to their intrinsic fibre structure and porosity, they offer a great damage tolerance. Therefore, they provide superb attenuation characteristics, as do polymer composites. The current compound systems consisting of ceramic components feature a rather low capacity for energy absorption in relation to their weight; this is a fact in dire need of a fundamental change. In regards to the development of new hybrid ceramic/polymer material compounds basic research of the material design and binding behaviour of the different components is necessary. The advantage of this development allows for a selective implementation of positive characteristics of one component in an integrated compound-system. This opens up completely new possible are-as of application, such as wear and tear resistant and chemically inert, energy absorbing elements for the construction of reactors or areas of medical technology. During the investigation, a few selected fibre-reinforced ceramic composite materials with a specific porosity were produced, while adjusting the amount of resin/hardening agent used, as well as modifying other parameters. This was followed by tests regarding the wetting with a polyurethane component. The characterisation and analysis of the hybrid compounds on a microscopic scale is achieved by means of optical microscopic examinations. The characterisation of the mechanical attenuation characteristics on the other hand is realised by means of DM(T)A. The flexural strength is determined by utilising a “three-point-bending test”.
Surface and Fracture Surface Analysis of Thermally Bonded Metal/FRP Joints
Authors: Nestler Daisy , Döhler Claudia , Wielage Bernhard , Wagner Guntram
Published: July 2015

The increasing implementation of fibre-reinforced plastics (FRP) leads to a broad utilization of metal/FRP joints. The examination of adhesively bonded metal/FRP joints is focusing on the maximum joint strength and the surface pretreatment used to promote it. A deeper understanding of the mechanisms behind the correlation is lacking. Along with the chemical condition of the surface (free chemical bonds, polarity, etc.) the surface morphology plays an important role. This study addresses the connection between the surface morphology and joint strength. The investigation of the surface morphology of the metallic joining area and the fractured surface of both joining partners by means of imaging and tactile methods and the results are presented.
Workpiece Shape Deviations in Face Milling of Hybrid Structures
Authors: Denkena Berend , Grove Thilo , Hasselberg Eike
Published: July 2015

A currently common method to design high-performance workpieces is to combine two or more materials to one compound. This way, workpieces can be composed of the most qualified materials according to local loads.When machining high-performance workpiece compounds (e.g. cylinder crankcases), high quality requirements concerning the accuracy of dimension and shape as well as the surface roughness must be fulfilled. However, machining of workpiece compounds leads to unfavorable changes of the workpiece quality in comparison to machining of the single materials. Significant shape deviations occur when different materials are machined alternately in one cutting operation. This is due to unequal material properties, cutting characteristics, chip formation mechanisms as well as characteristic interactions between the single components.The focus of this research is on the process understanding as well as on the identification of measurable shape deviation indicators that describe the surface finish of hybrid structures. Here, the indicators material height deviation, transition deviation at the material joint, surface roughness deviation as well as surface defects (e.g. scratches) on the surface are presented. The overall aim of this research is to predict the surface finish resulting from face milling an aluminum/cast iron compound or a polyurethane/cast iron compound.
Sandwich Structures: Analysis of Bonding Techniques between Faces and Core and the Effect of Internal Pressure
Authors: Müller Lena , Lehmann Benjamin , Gresser Götz T.
Published: July 2015

The following work was focused on the analysis of adaptable pressurized sandwich components. The investigations were carried out to study the influence of internal pressure on mechanical characteristics. The bonding quality between core material and outer layers is of particular importance. For analyzing the bonding quality peel tests were conducted. In order to investigate the influence of the internal pressure and also of a bonding technique on bending properties four-point bending tests were carried out. In addition, the pressure characteristics were studied with compression tests during which a compression die was pressed into the component. After the compression tests, the rebound properties of pressurized and standard components were observed and compared.
Requirements for a Process Chain for Manufacturing of Piezoceramic-Aluminum Sandwiches
Authors: Nestler Matthias , Hensel Sebastian , Drossel Welf Guntram , Müller Roland
Published: July 2015

Lightweight solutions and functional integration become more and more important in different fields of industry. In order to achieve a sensor and actuator functionality of shaped sheet metal parts, today a generally manual application step of the piezomodule is necessary. This subsequent process is time consuming and leads to high costs. In earlier studies a method was presented allowing the fabrication of a formable compound with an integrated sensor and actuator functionality. The formability of the compound is achieved using a viscous adhesive, surrounding the piezomodule during the forming operation. The low viscosity of the adhesive allows a relative movement between the piezomodule and the sheet metals and drastically reduces the transfer of critical strains to the piezomodule. Curing of adhesive takes place after the forming operation. To improve the efficiency of the process chain an advanced adhesive system with robust application properties has to be used. Furthermore, the productivity of several fabrication steps and their sequence in the process chain have to be verified and improved. The paper presents the process chain designed for automated production of formable sandwich sheets with integrated piezomodules, including the production steps for the fabrication of the semi-finished part as well as the forming operation. Aiming on a good formability during the shaping operation and on a stiff connection between the piezomodule and the sheet metal in the finished sandwich part, one focus is set on the adhesive properties required during the different process steps.
Experimental Investigation of the Shear Cutting Behaviour of Sandwich Panels
Authors: Stein Philipp , Übelacker David , Holke Dirk , Groche Peter
Published: July 2015

Continually increasing exhaust emission standards for automobiles and an increasing environmental awareness push design engineers to develop new constructive and material concepts. So-called sandwich panels, consisting of stiff facings and light-weight cores, offer the possibility to combine properties of different materials synergistically. When processing large quantities, as is the case in the automotive industry commonly used manufacturing processes for cutting sandwich panels, like sawing or milling, are not applicable. A common manufacturing process to cut metal sheets in high quantities is shear cutting. However, pre-trials of shear cutting of sandwich panels have shown that it is not possible to achieve flawless cutting surfaces with current process layouts. Characteristic types of failure like high bending of the facings, delamination effects, burr formation and an undefined cracking of the core material were ascertained. Thus, in this study, the influence of cutting parameters, such as the clearance and the punch diameter, on these types of failure is examined. Five different clearances between 0.025 mm and 0.4 mm with two punch diameters, 8 mm and 32 mm, were investigated. In order to compare the influence of different materials, three commercially available sandwich panels were studied. The chosen sandwich panels differ both in the face sheet thickness and the core material. Finally, the shear cutting force is measured to identify a possible correlation between the cutting force and the face bending. As a result, optimal clearances to minimize the face bending are derived. Additionally, the influence of the core stiffness on the cutting force is determined.
Combined Detachable Joints for Textile Reinforced Thermoplastic Composites with Embedded Sensor Networks
Authors: Modler Niels , Adam Frank , Weck Daniel , Winkler Anja
Published: July 2015

In regard to the realization of innovative lightweight constructions, textile reinforced composites show outstanding mechanical properties, e. g. adjustable high specific stiffness and strengths. Furthermore, these materials enable a process immanent integration of functional elements (f. e. conductors, sensors, actuators or electronic components) directly into the composite structure due to their layered built up. Currently, no joining technologies for such function integrative composite parts exists, which enable a simultaneous mechanical and electrical load transfer from part to part by only one joining element type. Therefore, the paper focuses on detachable functional interfaces, which enable the mechanical connection of two join partners and the transfer of electrical signals by contacting the composite embedded conductors. Investigations in regard to the selection of suitable joining elements and their behavior under mechanical and thermal loads are performed. The investigations show that the electrical resistances are low and not affected significantly by rising tensile loads or repetitive joining operations. Tensile tests using both single lap shear and double lap shear specimens show that the electrical contact almost exists until the mechanical failure of the joints occurs.
Process Combination of Hydroforming and Injection Moulding for the In Situ Manufacturing of Metal and Plastic Composite Structures
Authors: Albert André , Drossel Welf Guntram , Zorn Wolfgang , Nendel Wolfgang , Raithel Dirk
Published: July 2015

The use of lightweight structures is a major trend in the reduction of fuel consumption and CO2 emissions, especially in transport. Metal plastic hybrid structures are an efficient solution to use the best material at every point in the design space. In the state of the art production technologies, the metal parts are produced separately from the plastic parts. The injection moulding process is only used for forming the plastic parts and for joining. These process chains are very extensive. The article shows the development of new process combinations. The aim is a combination of metal forming and injection moulding in one die and one process. One part should be produced with every single stroke of the press.In the first step, deep drawing, injection molding and media based forming with the plastic melt were successfully merged in one tool and one process. It was possible to integrate the injection moulding process into a deep drawing machine. In the next step, it was possible to successfully combine hydroforming and injection molding. For this process combination the hydroforming process is integrated into an injection moulding press. Different surface structures of the metal tubes, such as sandblasting, knurling and laser structuring, were systematically tested regarding to their properties as an adhesion promoter. The target is to establish a purely mechanical connection between the hydroformed metal component and the injection moulded component from glass fibre reinforced plastic instead of the chemical bonding agents often used previously, such as Vestamelt®.
Toughening of Photopolymers for Stereolithography (SL)
Authors: Dorfinger Peter , Stampfl Jürgen , Liska Robert
Published: July 2015

Additive Manufacturing (AM) received a lot of attention in the last years. Organizations are using AM systems for a range of applications such as prototypes for fitting an assembly, tooling components, patterns for prototype tooling, functional parts and many more. Nearly a third is applied for functional parts [1][2]. Hence, the SL method provides a smoother surface finish than other AMT[3]. Not only is the smoother surface a benefit but the good precision is also a positive feature. The ongoing development of new material systems and applications make them suitable alternatives for conventional series production like injection molding or machined-core fabrication for foundry use. Small to middle series cores for faucets with quantities from around 50,000 pieces produced using AM methods are already a reality [1]. From the economical point of view, the SL is a cheap and fast process in comparison to AM systems. The SL technology used in this work is based on an active mask exposure, the digital light processing (DLP). The term DLP refers to the digital mirror devices which are used for selectively tuning individual mirrors on and off in order to selectively expose a photosensitive resin with visible or ultraviolet light. The resin contains a photoinitiator which triggers radical polymerization when irradiated with light. The polymerization process leads to a solidification of the resin, leading finally to a solid polymer part [4]. A digital Mirror Device (DMD) chip acts as a dynamic mask to expose a defined area on the bottom of a transparent material vat above the optical system. The generated picture enables layer-wise polymerization of the photosensitive resin resulting in a 3-dimensional object. The light source radiates light with a wavelength of 460 nm which means blue visible light. At this wavelength the curing takes place. At the Institute of Materials Science and Technology at the Vienna University of Technology six generations of these Blueprinter machines have been developed and built to date. The largest parts that a Blueprinter can currently generate are 110 x 110 x 80 mm3 with a resolution of 25 x 25 x 25 μm3. The wall thickness can go down to four pixels which means one tenth of a millimetre.
Preparation of Ni-C Thin Films for Strain Sensor Applications in New Hybrid Laminates with Thermoplastic Matrix
Authors: Wett Daniel , Nestler Daisy , Wagner Guntram , Wielage Bernhard , Seider Thomas , Martin Jörg , Gessner Thomas
Published: July 2015

Hybrid laminates with thermoplastic matrices offer clear advantages over laminates based on thermosetting resins. These include the formability, recyclability as well as the suitability for mass production, to name a few. The inline integration of smart systems like sensors and actuators in the hybrid laminates during the hot-pressing process is one of the long-term objectives of the Federal Cluster of Excellence MERGE. This work aims to deposit Ni-C thin films by dc magnetron sputtering on polyimide substrates for the application as strain sensors in hybrid laminates. During the first step hybrid laminates containing different polyimide foils were prepared by hot-pressing, this was followed by the mechanical testing and selection of the most suitable polyimide substrate for the Ni-C thin film deposition. The second part consisted of depositing Ni-C thin films by means of dc magnetron sputtering and utilising different Ni-C plug targets. The films were characterised regarding their growth rate, composition, structure and temperature coefficient of electrical resistance.
Virtual Composite Manufacturing Simulation Chain
Authors: Masseria Frédéric , Berger André , Kaiser Benjamin
Published: July 2015

Composite materials have been introduced in the 90’s in the car racing, naval and aeronautic sectors for weight reduction purposes. In the automotive industry, the introduction of composite materials to reduce also the weight of the vehicles leads to additional challenges for Virtual Prototyping on top of difficulties already encountered with metallic structures modeling. The impact of manufacturing on product performance is critical for composites, as the imperfections from the process may greatly affect the statics and crash performance of the final composite component. The paper will describe the state of the art of ESI Composite Solution on global composite manufacturing simulation chain (Forming, Injection, Curing, and Distortion) and how it couples to Structure/Crash through selected industrial examples.
pvT-Behavior of Polymers under Processing Conditions and Implementation in the Process Simulation
Authors: Freytag Rotraud , Pérez Gil José Antonio , Forstner Reinhard
Published: July 2015

The development of high performance products at lowest possible product development-time and costs is the demand of the plastics industry today. A successful use of process simulation to describe the behavior of complex structures and to minimize the technical and economic risks for companies requires application and process-relevant material data.The pvT-behavior of polymers is an essential parameter for process simulations. Especially the dependence of the specific volume of pressure and temperature [1, 2] under process conditions is not mapped to the existing measurement methods.In this study pvT measurements were performed on selected amorphous and semi-crystalline polymers (PP, HDPE, POM, PBT, and ABS) with a Pirouette pvT device, a combination of a dilatometer and Couette rheometer. The specific volume was determined as a function of temperature (25-300°C) and at pressures ranging between 200-1000 bar. On top of that, the influence of the cooling rate was also investigated by pvT measurements performed at cooling rates of 0.1°C/s, 1°C/s and 100°C/s.The coefficients for the 2nd domain Tait pvT-model, which is implemented in the software Autodesk Moldflow, were determined by fitting the experimental pvT data and comparing them with the measured curves. As a result, the semi-crystalline polymers show a shift of the transition temperature to lower temperatures and a reduction in the specific volume in the melt is observed. For validation, in a case study shrinkage results in real were compared with the simulation.
Support Structures in Lightweight Design for the Construction of Resource Efficient Bridges
Authors: Rudolph Enrico , Ehrlich Andreas , Gelbrich Sandra , Röhrkohl Meike , Kroll Lothar
Published: July 2015

Modern civil engineering is characterized by resource and energy efficiency, and functional integration. The focus of modern architecture is therefore increasingly on free-formed buildings with organic shapes and biomorphic structures. The basis of new buildings still consists of conventional materials like steel, glass and reinforced concrete. However, the applicability of these materials is limited, regarding lightweight design, freedom of design, efficiency and functional integration. Innovative projects either cannot be implemented, or would be put to enormous costs and expenditure of resources.The theoretical and experimental basis for this functionally integrated support structure was established within the scope of the research project “New lightweight structural components and processing technologies for the application in support structures”, supported by the Sächsische Aufbaubank SAB.The main objective was to develop material and design for a lightweight modular support structure and to implement it by means of innovative production methods. New approaches included the application of glass-fiber-reinforced plastic (GFRP) due to its favorable mechanical properties, low susceptibility to corrosion and load-adjusted dimensioning.In connection with the realization of the production, different technological concepts were analyzed with reference to their suitability, integration of required force transmission and further functions during and after production. The lightweight elements were analyzed on a laboratory scale with regard to their production and their mechanical properties. A holistic production and tool concept resulted from these tests, that pictures the complete process chain from textile to component. The results were implemented in practice in form of an interactive honeycomb-bridge which was built in Chemnitz.
Innovative Concepts for the Use of Composite Material Solutions in the Production of Automotive Cylinder Heads
Authors: Scharf Stefan , Baehr Rüdiger
Published: July 2015

This paper documents the initially made and generally applicable systematisation and classification for optimised design of automotive cylinder heads by using hybrid compound material solutions. Proceeding from this background, different technical variants for design and manufacture of cylinder heads are presented. The intention is to combine different materials, so that locally different stresses in modern cylinder heads may be taken up through the specific use of appropriate materials. On the basis of fundamental investigations into the bonding behaviour of different materials, appropriate opportunities for an effective reduction resp. overcoming of the interfering oxide layer are derived. With this in view new design approaches are presented. As the basis for assessment and evaluation of their performance potential different FEM and CFD calculations for temperature field analysis, strength prognosis and fatigue strength are shown. Finally special casting tests regarding the practical feasibility of the appropriate conceptions in production are presented.
Energy and Time Efficient Microwave Curing for CFRP Parts Manufactured by Filament Winding
Authors: Betz Stefan , Köster Fabian , Ramopoulos Vasileios
Published: July 2015

Process time reduction and energy/cost savings are usually in the focus of production process improvements. New technologies provide possibilities to achieve significant enhancements for relevant operation figures.Curing cycle times for CFRP manufacturing depend on several requirements: Type of resin, requested glass transition temperature, used equipment and energy source as well as sample size, weight, fibre volume ratio, fibre orientation etc. Conventional methods are mostly based on heat conduction while microwaves offer a selective and volumetric heating of the samples. Process time reduction and energy saving are the positive effects of the microwave curing technology.This paper will give an overview of the current status of this process technology not only focussing on technical aspects but also covering the process and economic effects.This work has been performed under the German BMBF project 02PJ2131, FLAME under the program Energy Efficient Light Weight Construction.
Braiding of Branches for the Fibre Composite Technology
Authors: Küppers Simon , Thumm Johannes , Müller Lena , Ewert Dagmar , Gresser Götz T.
Published: July 2015

In many areas of fiber composite technology there is a great need for a solution of how to manufacture nodal elements and/or ramifications with an optimized force flow process and by machine, i.e. economically. Examples are hubs of wind power plants, branch points in framework constructions in the building industry and air and space travel, the automotive industry, ramified vein prostheses in medical technology, or the connecting nodes of bicycle frames. Motivated by this, the potential of plant ramifications as a model for new compound fiber constructions was investigated. Ramified species with pronounced fiber matrix structure served, inter alia, as biological models. The PBG Freiburg examined tree-formed monocotyledons of the genera Dracaena and Freycinetia [1], the BTU Dresden column cacti of the genera Pilsocereus and Myrtillocactus [2]. The plants exhibit Y-shaped and T-shaped ramifications, whose angles resemble those of the ramified technical construction units that are to be optimised bionically. As the investigations confirm, the ramifications, which are nearly completely unexplored, are characterised by very interesting mechanical characteristics, like e.g. good-natured breaking behavior and good oscillation damping caused by high energy absorption, as well as a high lightweight construction potential. The results demonstrate the high potential for a successful technical transfer of the results of the proposed project.In this paper, three different types of braided branches are represented. Firstly, the aforementioned nature-inspired Y-junctions are shown. Secondly, a type of branch with a special braiding technique that allows branches with asymmetric design of the arms and a braiding technique for the automated production of loop connections is presented.
Applications of Variable-Axial Fibre Designs in Lightweight Fibre Reinforced Polymers
Authors: Richter Emanuel , Spickenheuer Axel , Bittrich Lars , Uhlig Kai , Heinrich Gert
Published: July 2015

A load dependent and curvilinear respectively variable-axial fibre design can notably enhance the strength and stiffness of lightweight components compared to fibre reinforced structures made of common multiaxial fibre textiles. At the Leibniz-Institut für Polymerforschung Dresden e. V. (IPF) special design strategies are in the focus of current studies. Two currently developed components made of carbon fibre reinforced plastics, a lightweight three-legged stool and a lightweight recurve bow riser, are described within this paper.
Application of a Composite Hot Shearing Tool Manufactured by Co-Spray Forming
Authors: Rentsch Rüdiger , Grohmann Olaf , Schulz Alwin , Uhlenwinkel Volker
Published: July 2015

In modern manufacture, like in automotive industry, high quality products and high output rates as well as low costs are achieved by highly efficient processes. Optimized tool design represents a key factor for such processes, leading to long tool life and hence to low tooling costs. Early in the industrial manufacturing chain of roller bearings for example, hot bars are sheared into billets, which are subsequently transported automatically to the first forming stage of a press. The shear blades should have a high wear resistance at high temperatures. In this study the first bi-metal composite shear blade made by spray-forming has been developed and tested in industrial environment. The composite tool has been deposited in a co-spray forming process to directly combine a hard-facing alloy layer with a hot working steel body in order to take advantage of the high microstructural homogeneity and the low segregation generated in spray forming. After machining, heat treating and quality inspection of the new material composite, the hot working tool was used in manufacture to prove its wear resistance and durability. The results show that the interface properties of the composite are of high quality and the material has a lower vulnerability to cracks after use in production than the conventional tool, respectively material. Only the porous zone near the interface leads to fissures which are partially going deep into the tool. Hence the parameters of the co-spray forming process need to be improved.
Consideration of Accuracy of Quantitative X-Ray CT Analyses for Short-Glass-Fibre-Reinforced Polymers
Authors: Salaberger Dietmar , Jerabek Michael , Koch Thomas , Kastner Johann
Published: July 2015

A novel methodology for the characterization of short fibre reinforced polymers using Xray computed tomography is introduced and evaluated. Scans with high resolution lead to data quality that allows for single fibre examination. Data analysis takes the information of local direction into account to determine centre lines and start- and endpoints. Reproducibility and accuracy are determined for glass fibre filled Polypropylene. Nine analyses of the same specimen show very small standard deviation for fibre length and orientation distribution. Accuracy of up to 97 % is determined by comparing the XCT result with semi-automatically generated ground truth. Variation of resolution shows no influence on fibre orientation but a decrease in mean fibre length for lower resolution. The proposed method leads to accurate results at 2 μm voxel edge length or below for the investigated material system.
High Temperature Squeeze Casting of Nickel Based Metal Matrix Composites with Interpenetrating Microstructure
Authors: Edelbauer Johannes , Schuller David , Lott Oliver , Nagel Alwin
Published: July 2015

High temperature squeeze casting enables the fabrication of composite structures for alloys with high melting points, suitable for structural and tribological applications at high temperatures. Nickel-chromium alloys with chromium contents of about 20 wt% are extremely resistant to corrosion and exhibit operation temperatures up to 1000 °C due to the high solubility of chromium in nickel and its high melting point. The creep and wear resistance of the metal matrix composite material (MMC) is achieved by a stable ceramic backbone of Alumina with a bimodal pore structure. The fabrication of interpenetrating nickel-chromium/alumina MMCs, namely NiCr8020/Al2O3/50pp, at temperatures above 1550 °C is shown. A special infiltration tool geometry has been used to withstand thermal and mechanical strain, necessary for the infiltration of preforms with 40 mm in height. The infiltration was performed in a unique high temperature squeeze casting device with tool temperatures of about 700 °C. Infiltration duration (pore filling) was as long as about 12 s. For this, the thermal management of the tool is the demanding part. Whereas the inner cavity has to be as hot as possible to enable infiltration and to prevent premature solidification. In contrast the outer side of the infiltration tool has to be as cold as possible to withstand the infiltration pressure applied directly to the squeeze casting tool.
Safety of greenlight photoselective vaporisation of prostate in lower urinary tract symptoms due to benign prostatic hyperplasia in patients using anticoagulants due to cardiovascular comorbidities
Authors: Cakiroglu Basri , Sinanoglu Orhun , Dogan Akif Nuri
Published: July 2015

Lasers have been used in the management of benign prostatic hyperplasia for the last two decades. To be comparable, they should reduce or avoid the immediate and long-term complications of transurethral resection of the prostate (TURP) or open prostatectomy (OP), especially bleeding and need for blood transfusion. Although Holmium laser treatment of the prostate was compared frequently in terms of cardiovascular safety with TURP or OP, photoselective vaporisation of the prostate (PVP) was not largely evaluated. In this article we analyzed the current literature to see if there is convincing data to support the observation of some authors that use of PVP is associated with increased safety in patients on anticoagulants with cardiovascular comorbidities. With this purpose a Medline search between January 2004 to March 2013 was performed using evidence obtained from randomised trials, well-designed controlled studies without randomisation, individual cohort studies, individual case control studies and case reports Results: In the last 10 years, several case-control and cohort studies have demonstrated the efficacy of PVP as well as its safety in patients with cardiovascular comorbidities using anticoagulants. The results confirmed the overall lower perioperative and postoperative morbidity of PVP, whereas the efficacy was comparable to TURP in the short term, despite a higher reoperation rate. Conclusion: Although it is still developing, PVP with KTP or LBO seems to be a promising alternative to both TURP and OP in terms of cardiovascular safety and in patients using anticoagulants.
Use of transvaginal ultrasound in females with primary bladder neck obstruction. A preliminary study
Authors: Galica Vikiela , Toska Elona , Saldutto Pietro , Galatioto Giuseppe Paradiso , Vicentini Carlo
Published: July 2015

Introduction and aim: The video-urodynamics study is the principal exam to establish a possible primary bladder neck obstruction (PBNO) condition. While trans-rectal ultrasonography plays an important role in the evaluation of the low urinary tract symptoms (LUTS) and the severity of bladder outlet obstruction (BOO) in men, the use of the transvaginal ultrasound (TVUS) in women with symptoms suggesting BOO remains unclear. We tried to check the utility of the TVUS in women with PBNO condition. Material and methods: We selected female patients which presented BOO without pelvic organ prolapse (POP). According to the data of the video-urodynamic exam we selected the patients with the suspicion of PBNO. A TVUS in basal and during micturition was performed before and after surgery. Results: TVUS showed a closed bladder neck bladder in basal condition and during micturition similarly to the fluoroscopic image during video-urodynamics. The mean distance from bladder neck to the vaginal mucosa resulted 1.3 cm in this patients. Conclusions: TVUS results worthy in the evaluation of patients with PBNO before and after surgery.
Correcting and sharing our complications. Misplacement of pigtail catheter, during a Robot Assisted Pyeloplasty. Clinical findings, diagnosis, possible causes and endoscopic treatment
Authors: Stravodimos Konstantinos , Katafigiotis Ioannis , Fragkiadis Evangelos , Tyritzis Stavros , Constantinides Constantinos A.
Published: July 2015

Objective: Robotic assisted pyeloplasty (RAP) is rapidly adopted by surgeons around the world. We present a unique complication of the technique, consisting of pigtail misplacement, which was endoscopically resolved. We discuss the clinical findings, differential diagnosis and principles of endoscopic treatment. Materials and Methods: A 41 years old female patients underwent transperitoneal right side RAP with the Hynes-Anderson technique for ureteropelvic junction obstruction. Pigtail was placed intraoperatively in an antegrade fashion. Post operative course appeared normal but Kidney-Ureterer-Bladder(KUB) X-ray, revealed a misplaced pigtail. Patient underwent a semirigid ureterorenoscopy demonstrating that the pigtail was exiting the collecting system in the rear line of suturing between continuous sutures. Pigtail was retrieved with a stone retrieval forceps with short upward motions in the renal pelvis under fluoroscopy and then removed from patient, in order to avoid stressing the anastomosis. No leakage was noted in fluoroscopy, a pigtail was correctly placed and patient recovery was uneventful. Results: Retrograde pyelography was the key to accurate diagnosis and endoscopic treatment, because the exact point of exit and anastomosis integrity were established. Retrieval of the pigtail was the most challenging part. Lack of proper visualization and mobilization of the rear part of the anastomosis during surgery, combined with lack of tactile feedback, because of robotic instrumentation, were of critical importance in the manifestation of such a mishap. Endoscopy facilitated case resolve, but proper handling is required to protect the anastomosis. Conclusions: The introduction of novel techniques can carry the burden of novel complications. A surgeon must always keep in mind the complications inherent to the technique and at the same time the limitations of the equipment used, especially the lack of tactile feedback in robotic instrumentation.
Patch bulging after plaque incision and grafting procedure for Peyronie’s disease. Surgical repair with a collagen fleece
Authors: Fabiani Andrea , Fioretti Fabrizio , Filosa Alessandra , Servi Lucilla , Mammana Gabriele
Published: July 2015

The incision/excision and grafting techniques (PIG) for surgical therapy of Peyronie’s disease (PD) have gained popularity in recent years. Several different graft materials have been used but the ideal graft has yet to be established. The use of grafting materials could cause complications. In the daily clinical practice it will always be more frequent to manage complications arising from their use. We present herein the case of a patch bulging repaired with a ready-to-use collagen fleece (Tachosil®, Takeda, Linz, Austria, Europe) in a 61 years old man subjected to intervention of geometric corporoplasty with Paulo Egydio technique using an acellular collagen material (Xenform® patch, Boston Scientific, Natick, MA, USA) as graft. We also discuss the possible implications of PIG procedure.
Profile and correlates of functional status in elderly patients presenting at a primary care clinic in Nigeria
Authors: Ajayi Samuel A. , Adebusoye Lawrence A. , Ogunbode Adetola M. , Akinyemi Joshua O. , Adebayo Ayodeji M.
Published: July 2015

Background: Assessing the functional status of elderly patients is central in measuring their health outcome. Little is known about the functional status of elderly patients attending our primary care clinic in Nigeria.Objective: To assess the correlates of functional status in elderly patients presenting at the General Outpatient Clinic of the University College Hospital, Ibadan, Nigeria.Method: A cross-sectional study of 360 randomly selected patients aged 60 years and above was undertaken to assess their functional status by scoring their basic activities of daily living (BADL) using the Modified Bathel Index. An interviewer-administered questionnaire was used to obtain the socio-demographic data, anthropometric measurements and morbidities of each patient.Results: The mean age was 69.1 ± 6.6 years with a female-to-male ratio of 1.9: 1. The prevalence of overall functional disability (defined as when assistance was sought in the performance of at least one of the components of BADL) was 88.3%. The highest prevalence of functionaldisability was experienced in the area of personal hygiene and grooming (95.3%) and transferring from bed to chair (95.3%). Overall functional disability significantly increasedwith increasing age (χ2 for trend=14.004, p < 0.0001), living in a polygamous family unit (p = 0.025), and lack of formal education (p = 0.020).Conclusion: Functional disability was high amongst the elderly in this setting. Age, education, and living in a polygamous type of family unit had significant influence on the functional status. High premium should, therefore, be placed on considering these factors in reducing functional disability in the elderly.
Single and Multiple Gene Manipulations in Mouse Models of Human Cancer
Authors: Lehman Heather L. , Stairs Douglas B.
Published: July 2015

Mouse models of human cancer play a critical role in understanding the molecular and cellular mechanisms of tumorigenesis. Advances continue to be made in modeling human disease in a mouse, though the relevance of a mouse model often relies on how closely it is able to mimic the histologic, molecular, and physiologic characteristics of the respective human cancer. A classic use of a genetically engineered mouse in studying cancer is through the overexpression or deletion of a gene. However, the manipulation of a single gene often falls short of mimicking all the characteristics of the carcinoma in humans; thus a multiple gene approach is needed. Here we review genetic mouse models of cancers and their abilities to recapitulate human carcinoma with single versus combinatorial approaches with genes commonly involved in cancer.