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Über dieses Buch

This book comprises the proceedings of the conference “Faszination Hybrider Leichtbau 2018”, which took place in Wolfsburg.

The conference focused on new methods and technologies for the development and production of multifunctional and hybrid lightweight solutions in large-scale vehicle manufacturing. Further, it promoted the exchange of insights and lessons learned between experts from industry and academia.

Lightweight design and construction are key technologies for the development of sustainable and resource-efficient mobility concepts. Material hybrid structures, which combine the advantages of different materials (e.g. fiber-reinforced plastics and metals), have a high potential for reducing weight, while simultaneously expanding component functionality. However, the efficient use of functional integrated hybrid structures in vehicle construction, requires innovations and constant developments in vehicle and production technology. There is a great demand for affordable lightweight construction in mass production that takes into account the increasing requirements in terms of variant diversity, safety and quality- particularly with regards to new methods and technologies.

Inhaltsverzeichnis

Frontmatter

Projects within the Open Hybrid LabFactory

Frontmatter

MULTI MATERIAL DESIGN. A CURRENT OVERVIEW OF THE USED POTENTIAL IN AUTOMOTIVE INDUSTRIES

Abstract
Multi material design represents the current forefront of the lightweight design trend for automotive mass production. The combination of different materials (such as metals and fiber reinforced composites) can be used to improve components in terms of various requirements (component properties, manufacturability, costs, etc.). With the reduction of component weight, low costs and feasibility in mass production, hybrid design approaches are the ideal compromise for the mass automotive lightweight construction of the future. However, there is currently no selection strategy for a specific definition of potential hybrid component areas. The basis for developing a selection strategy for potential vehicle sections in multi material design is a comprehensive overview of current examples. The acquisition and analysis of more than 150 components from the automotive industry and research make it possible to identify the main implementation features and drivers of hybrid design in automotive engineering. This contribution shows that the potential of hybrid design approaches in vehicle technology can usually be limited to a few arguments, such as cost-efficiency or weight reduction. The article shows that the hybrid design is marketed as an innovation feature. A particularly suitable group of components for the application of hybrid design could only be identified to a limited extent. A statement about the “correct” use of multi material design based on the compilation of current examples could not be identify clearly. This confirms the need for a targeted selection strategy for multi material components or an improvement indicator.
Benjamin Bader, Eiko Türck, Thomas Vietor

DATA MINING APPLICATIONS IN MANUFACTURING OF LIGHTWEIGHT STRUCTURES

Abstract
Advanced manufacturing of automotive lightweight structures implies the introduction of new process steps into traditional process chains. Due to the combination of materials and their functional integration, those process steps show increased complexity. As a result, manufacturing faces new challenges regarding a constant and high product quality. A widely discussed approach to encounter these new challenges is the analysis of manufacturing process data by applying data mining methods. Benefits of the underlying digitalization approach are found in extensive transparency, product quality assurance, decision support or even in an automated manufacturing control.
Application fields of data mining in manufacturing of lightweight structures, the design of an appropriate context-based data acquisition infrastructure and special aspects of lightweight structures manufacturing influencing the CRISP-DM data mining workflow are discussed. The application of machine state recognition in extrusion of a glass fiber reinforced plastic rib structure exemplifies the proposed aspects.
Sebastian Gellrich, Marc-André Filz, Johannes Wölper, Christoph Herrmann, Sebastian Thiede

DEVELOPMENT AND NUMERICAL VALIDATION OF COMBINED FORMING PROCESSES FOR PRODUCTION OF HYBRID PARTS

Abstract
This paper gives an overview about different one-shot processes of hybrid forming and joining of semi-finished products using conventional forming presses. An example of forming with a variothermal tool is given by forming a sandwich structure. Different aspects of the forming process are addressed, including the interlayer formation during the process. Here, the objectives are the complete impregnation of the fibres, the consolidation and a firm bond. It is shown, that in contrast to that, the objective when forming a sandwich sheet is to prevent delamination. For forming a hybrid battery tray, a process was developed that combines the advantages of organic sheet forming and compression molding. In order to predict the quality of the bonding of the glass mat reinforced thermoplastic to the organic sheet the temperature evolution is numerically analysed.
Bernd-Arno Behrens, Sven Hübner, Alexander Chugreev, André Neumann, Nenad Grbic, Henrik Schulze, Ralf Lorenz, Moritz Micke, Florian Bohne

Functional Components

Frontmatter

HYBRID COMPONENTS WITH FUNCTION INTEGRATION FOR CRASH RELATED APPLICATIONS IN ELECTROMOBILITY

Abstract
In times of major changes in the field of automotive drive concepts, lightweight construction as a key technology is particularly important for the reduction of vehicle mass and thus for sustainable mobility. The most significant synergy effect can only be achieved considering all three principles of lightweight construction: material-, structural- and system-lightweight construction.
As a part of the BMBF-funded project thermoPre®, by pursuing this approach the substitution of a motor carrier in die-cast aluminum construction with steel attachments was investigated. For this purpose, the entire potential of the lightweight construction on the reference component was determined and maximized including a cost-efficient production. The result is a continuous glass fiber reinforced thermoplastic (gfrp) component, which shows the high potential for weight and cost minimization by integrating existing attachments and inserts into the component manufacturing process.
Based on the aluminum component, a material appropriate design with subsequent topology optimization and final component design was carried out. Using the finite element method simulations, a load-capable component design was determined. The final design of the engine carrier and the necessary material blanks came from a series of optimization loops, which ultimately led to the production of prototypes. These were tested according to the requirements of the OEM, inter alia crash tests, whereby an equal and partly even improved performance was proven.
Confirmed by the good results from this research project, the implementation of a mass production of such components is planned.
Sebastian Iwan, Frank Schettler, Wolfgang Nendel, Lothar Kroll

COMPOSITE ENGINE BLOCK – CHALLENGES FOR DESIGN AND MATERIAL

Abstract
A hybrid engine block including a metal supporting structure and a composite plastic housing shall be designed and manufactured. The focus lies on the material selection, adapted to the engine block requirements, and the analysis of the joint area by pressure and leak tight tests. Several surface treatments are applied and compared to each other.
Melanie Jauernick, Christine Schütz, Joachim Sterz, Birte Horn

DEVELOPMENT OF A LIGHT-WEIGHT SEAT STRUCTURE USING A HYBRID MATERIAL APPROACH

Abstract
Carbon fibre composites are lightweight, and provide a high strength solution for automotive applications, however, the associated material and processing costs are relatively high. This project focused on the development of a composite front seat back (FSB) by primarily reducing cost through materials and component design without compromising safety. The use of cheaper, lower strength materials and low-cost production methods was explored. A hybrid light-weight material system consisting of carbon fibre non-woven and a low-cost long fibre reinforced thermoplastic was developed. Consequently, bonding solutions for dissimilar materials including the exploration of surface preparation techniques and their impact on the composite bond strength were investigated. The employment of flame and blown ion plasma treatment resulted in a 300 % increase in shear strength between inner and outer seat material. As a result, a unique materials and production solution that met the performance criteria with continued reduction in weight and cost was achieved.
Claudia Creighton, Mandy de Souza, Russell J. Varley, John Antony

Smart Production/Smart Components

Frontmatter

SMART SYSTEM INTEGRATION – POTENTIALS AND CHALLENGES IN THE INTEGRATED CONDITION MONITORING OF LIGHTWEIGHT STRUCTURES

Abstract
In the field of mobile applications, the use of lightweight structures based on carbon fibres is increasing more and more. Due to its high fracture toughness, the material reacts to mechanical overloads usually with invisible initial damage, such as delamination, intermediate fibre breaks or fibre breaks, which can lead to failure of the component. Such damage substantially affects the structural integrity of the structure, which requires its detection, monitoring and repair. At present, such fracture behaviour of fibre composite structures can only be measured with great effort and usually requires long inspection times (e.g. computer tomography, infrared spectroscopy or destructive testing methods). The monitoring of the structural integrity in real time by means of material-integrated sensors and signal processing electronics is therefore imperative and requires novel material and technology concepts for the large-scale functionalization of fibre-reinforced composite structures.
Due to the laminate shell construction, high-performance composite structures based on fibre-reinforcement allow the functionalization by sensors, actuators and microelectronics and thus an improvement in the performance and functional density of such lightweight structures. Continuously innovative manufacturing technologies for active systems based on micro- and nano-effects offer special advantages. These enable the integration of functional elements into textile-based, fibre-reinforced semi-finished products and preforms. In order to achieve a reliable integration of additional functional diversity, methods are being developed for the design and integration of active transducer elements in lightweight structures. For this purpose, a combination of in-situ and in-line processes is used, which includes the injection moulding process with functionalized polymer layers to apply electrical contact and mass printing processes.
In this contribution, concepts and strategies for the integration of sensors and their processing electronics into fibre-reinforced lightweight structures will be presented and their challenges in technological implementation as well as their potentials in terms of resource saving will be demonstrated and discussed.
Michael Heinrich, Ricardo Decker, Marco Walther, Lothar Kroll

POTENTIALS OF LOAD CARRYING CONDUCTOR TRACKS IN NEW VEHICLE STRUCTURES

Abstract
Digitization, autonomous driving and lightweight construction are the major future challenges in automotive engineering. This means that more and more complex driver assistance systems, engine control units, infotainment systems, actuators, sensors, etc. must be installed and wired. However, from a lightweight point of view, these cables are additional weight without any structural benefit and only affect the weight balance.
Within this paper a new approach to integrate conductor tracks directly into composite structures is presented. In contrast to conventionally integrated conductor tracks, the conductor tracks which are presented here are designed for load carrying purposes. As a result, the wiring costs, the assembly costs and the weight can be reduced significantly. Carbon Fiber Reinforced Polymers (CFRP) are used for this purpose, which show great potential for lightweight construction and, due to their layered structure of individual layers, enable the integration of load-bearing conductor tracks.
Instead of conventional copper wires, different metal foils are inserted into the CFRP vehicle structure stack and used as a conductor track. The single layers can be stacked and arranged individually. In this way, the efficiency of the overall structure can be controlled and optimized.
In order to be able to analyze and evaluate the potential of CFRP with structurally integrated conductor tracks, analytical calculations, mechanical tests and investigations of the electrical properties are carried out. Finally, a demonstrator is manufactured to prove the power supply and the bus communication within the CFRP-structure.
Alexander Pototzky, Daniel Stefaniak, Christian Hühne

NUMERICAL AND EXPERIMENTAL INVESTIGATION OF FIBER REINFORCED BIOCOMPOSITES AS STRUCTURAL PARTS IN AUTOMOTIVE APPLICATIONS

Abstract
In the automobile industry, bio-based component structures such as natural fiber reinforced thermoplastics mostly use fiber fleeces as reinforcement. As example the interior door trim parts of the Golf VII are made of natural fiber fleeces. However, the component properties of natural fiber fleeces are not sufficient for load-bearing structures. Hence, their application has been limited to interior trim parts.
In order to expand the use of bio-based fibers for load-bearing components, new technical and ecological synergies are necessary. The combination of a thermoplastic PP matrix with a mix of glass and flax fibers does create synergistic effects on many properties. As natural fibers bleached flax fibers are used. In addition to natural fibers, also the use of recycled short fiber reinforced PP as a matrix polymer is investigated. The present study shows that these bio-based and recycled materials can be used for load-bearing component structures. Moreover the use of process simulation as a tool for developing and optimizing the manufacturing chain of a seat shell is presented.
The purpose of simulating the forming process of a structural part is to determine how the mechanical properties in the final part will be like as these properties highly depend on the fiber orientation. Therefore a draping simulation which follows the continuum mechanics approach and takes the material behavior as well as the process conditions into account was performed. Since the main objective of process simulation is to achieve the convergence between the virtual and the physical product, great care must be taken to characterize the material behavior at process relevant conditions which is the main input for an FE simulation. Therefore the material behavior was characterized in terms of thermal, mechanical and strain rate depended properties. Subsequently a crash simulation was conducted in order to analyze the crash behavior of the seat shell.
Benedikt Lahl, Nikita Pyatov, Christian Busch, Stefan Hartmann, Hans-Josef Endres, Tim Andreas Osswald

Design and Simulation of Hybrid Structures

Frontmatter

INNOVATIVE HYBRID MATERIAL CONCEPTS AND THEIR VIRTUAL SAFEGUARDING

Abstract
New innovative manufacturing technologies allow the production of lightweight structures in multi- material design. By providing a high functional integration the economic mass production becomes feasible, which is needed for their use in car production. However, numerous issues in connection with an efficient and cost-effective series production and assembly of lightweight structures in multi material design are not yet fully solved. This paper covers three publicly funded research projects with participation of inpro. All of them belong to the FOREL-Cluster (research cluster electro-mobility).
The projects LEIKA (resource-efficient mixed-material construction for lightweight car bodies), ReLei (manufacturing and recycling strategies for electric mobility for recycling of fibre reinforced lightweight structures in composite hybrid constructions) and SamPa (integral production of hybrid lightweight sandwich structures with particle foam and injection moulding for mass production) cover several aspects concerned with modern hybrid car-body designs. Common to all of them is the development of appropriate simulation strategies followed by virtual safeguarding of the manufacturing process.
Henning Gleich, Frank Meißen, Kim Kose, Christian Paul

CARBON CARRIER – INTEGRATED CONCEPT FOR INNOVATIVE INTERIOR STRUCTURES

Abstract
With the common developed concept Carbon Carrier, Bertrandt and SGL show how new vehicle structures can be designed. In addition, it shows how it can be possible to make technologies visible and touchable to the end customer. The focus of the project is the use of available or soon available technologies for glass or carbon fibre reinforced plastics with a thermoset matrix or thermoplastic polymer matrix.
Michael Hage, Benjamin Wagner, Frank Preller

TAILORED STACKED HYBRIDS – AN OPTIMIZATION-BASED APPROACH IN MATERIAL DESIGN FOR FURTHER IMPROVEMENT IN LIGHTWEIGHT CAR BODY STRUCTURES

Abstract
In latest body-in-white (BIW) concepts, engineers take into account a wider range of different materials to pursue a multi-material design approach. However, the lightweight potential of common materials like steel, aluminum or even fiber-reinforcement plastics (FRP) is limited. In keeping with the motto “the best material for the best application”, a new approach for a top-down material design is introduced. With the aim to develop an application tailored material, the multi-material concept is adapted for the thickness dimension of the component. Within this contribution a new optimization- based design methodology is applied on a stiffness relevant car body part. Starting with benchmark simulations of a reference BIW structure, a critical car body component is determined by an internal energy based method and a subsequent sensitivity analysis. The identified demonstrator component is later subdivided into multiple layers and submitted to a first optimization loop in which the developed methodology varies the material parameters for each single layer. Once an optimum for the through-thickness properties of the part is found, further optimization loops with concrete material pendants and manufacturing restrictions are carried out. The result is a hybrid laminate part consisting of steel and FRP plies. To achieve a further improvement in body characteristics and lightweight, the investigated part is redesigned by the aim of topology optimization. Finally, the tailored hybrid stacks are validated in BIW simulations and compared with the reference. The optimization-based approach allows a weight reduction up to 25 % while maintaining or even improving the BIW properties.
Alan A. Camberg, Ina Stratmann, Thomas Tröster

A MANUFACTURE CONSTRAINED DESIGN METHODOLOGY APPLICATION FOR A TAILORED FORMING HYBRID COMPONENT

Abstract
Components with high performance, such as light weight, long life-cycle, good cost-benefit and other specific properties, are a constant goal of the industry. To achieve such performances, a constant progress is required in both manufacturing and design processes. These two areas must develop together and connected, at the same time that one challenges the other. Tailored Forming is a new manufacturing technique in development, which consists in a process chain to create massive hybrid material structures made of two different metals. This new technology presents a new range of manufacturing restrictions and requires a suitable design methodology to deal with the multi-material problem. The objective of this paper is to present an overview of the methodology that is currently being used to generate feasible designs for Tailored Forming. This methodology consists in an optimization tool that searches for an optimal material distribution and generates a first concept for the component, and a parametric analysis that generates a large solution space with a finer ready-to-use design result. Some examples of the applicability of these tools are here showed, with focus on a current Tailored Forming demonstrator, which is a hybrid shaft. Despite the simplicity of this application, it involves a challenging implementation, due to the manufacturing restrictions present. At the end, a final design is presented, which is not only suitable for the manufacturing process but also raises the advantages that this technology provides.
Renan S. Siqueira, Roland Lachmayer

New Production Technologies

Frontmatter

MATERIAL- AND PROCESS CHARACTERIZATION OF FIBRE-METAL-ELASTOMER LAMINATE COMPONENTS WITH HIGH FORMING DEGREES

Abstract
Hybrid material concepts provide a high variability in the resulting part properties, and thus are often applied to satisfy multiple component demands. Fibre-metal laminates (FML) are widely spread in aerospace applications and are being used for decades as they show a high lightweight potential and a good fatigue behaviour. However, a broad conventional use of hybrid laminates in the automotive sector is not existing until today. The high manufacturing costs, caused by the surface pre-treatment of the metal layer, as well as long process cycles and a limited formability of current laminates are not suitable for automotive applications.
This paper presents an approach, which allows the processing of hybrid laminates for high-volume applications and enables high forming degrees of the manufactured parts. As an additional elastomer layer is used to separate the metal from the fibre reinforced layer, carbon fibre reinforced polymers (CFRP) can be used instead of conventional glass fibres, preventing a galvanic corrosion between carbon and the metal. In addition to the manufacturing process itself, the influence of the formability will be discussed with regards to the distribution of the laminate layers, determining achievable forming degrees of the manufactured fibre-metal-elastomer laminate (FMEL) specimen. The laminate behaviour during the forming of the uncured laminate will be described by analysing micro sections. Furthermore, the results of an experimental modal analysis will be presented in order to determine the damping properties of the investigated hybrid laminates.
Sven Roth, Sven Coutandin, Jürgen Fleischer

Material Concepts

Frontmatter

FILM-ADHESIVES FOR POLYMER-METAL HYBRID STRUCTURES FROM LABORATORY TO CLOSE-TO-PRODUCTION

Abstract
For achieving efficient lightweight materials, automotive development focusses more and more on hybrid plastic structures. In this context target was to combine plastic and steel to develop a cost and weight optimized hybrid structure. Their performance strongly depends on the adhesion between the combined materials. Mechanical interlocking is commonly used for the joining of the two materials. However, an adhesive bonding of the polymer and metallic surface is more effective. Therefore, different kinds of adhesion promotion primers are available. Several of these were tested by SITECH Sitztechnik GmbH and within the project “TRoPHy2” by Salzgitter Mannesmann Forschung GmbH and the project partners. Regarding the tested primer systems, the multilayer film-adhesives by nolax AG showed the best performance. The film-adhesives were developed for hybrid structures for interior parts with decorative applications, for example metal decor parts out of aluminium with a thermoplastic back injection moulding layer.
The suitability of these film-adhesives on steel surfaces was proved within a large test program including adhesion, corrosion, forming and other automotive processing steps. Among these tests suitability for large-scale production of film coated steel was also estimated. All tests showed good results.
At the opening of the Open Hybrid LabFactory e. V. (OHLF) a first hybrid seat structure, produced by injection moulding, was presented. This structure was validated regarding to function and safety requirements. In view of a large-scale production, first lamination tests were done on the coil coating line of Salzgitter Flachstahl GmbH. A series launch is possible and economic lightweight structures are realizable.
Thorsten Schnettker, Philipp Dreessen, Klaus Dröder, Christian Vogler, David Koch, Thomas Frey, Benjamin Poller, Andreas Wedemeier, Christian Vree, Jörg Kosowski, Daniel Riss

TESTING OF METAL CONNECTIONS USING ADHESIVE BONDING COMBINED WITH SELF-PIERCING RIVETING

Abstract
A modern car body structure is driven by the multi-material design approach. The best material at the correct place is the objective. Consequently, components made of dissimilar materials need to be joined and the applied joining technology becomes a key issue for crashworthiness and structural reliability. In the present work, connections between steel and aluminium using adhesive bonding combined with self-piercing riveting and their structural design are investigated. The safe application of this hybrid joining technology in a vehicle structure requires detailed knowledge about its mechanical behaviour. For that purpose, riveted, bonded and hybrid connections need to be characterized under tension, shear and mixed mode loading. In the present work, results obtained from a novel test setup are presented. The response of self-piercing riveting and adhesive connections is discussed separately as well as the interaction between both joining technologies. Furthermore, a new test setup for adhesively bonded and point-wise connected components is presented. Here, load combinations comparable to a vehicle crash are introduced into the connections. The developed setup facilitates successive failure of multiple connections and enables a broad validation of numerical connection models.
M. Reil, O. Knoll, D. Morin, M. Langseth

APPLICATION OF INNOVATIVE MATERIAL CONCEPTS FOR SAFETY LIGHTWEIGHT INSIDE CARS USING ALTERNATIVE POWERTRAINS

Abstract
New megatrends in the automotive sector like alternative powertrains, autonomous driving or car sharing but also continuous improvements like increased safety regulations or CO2-emission standards can be influenced directly but also indirectly by an application-orientated selection of the used material or material combination. Thereby a new generation of material concepts can help to fulfil the partly divergent requirements and conflict of objectives consisting of strength, stiffness, energy absorption or lightweight. Further, the materials must be suitable for volume production and easy to integrate into established manufacturing processes like cold or hot forming and assembling, especially joining. Of course, new materials should be cost-effective, recyclable and completely simulatable.
To reach those targets, material scientists have different approaches like developing a monolithic metal or a compound structure, varying by fundamental basics like alloying elements, microstructure, number of phases, homogeneity, anisotropy, cross-sectional profile but also layer set-up and order [1].
The present paper takes up the mentioned diversity and introduces into different further developed material concepts which can be differentiated into opportunities for creating tailored properties of austenitic cold-hardening stainless steels, surface structured thin steel sheets and steel-polymeric composite structures. For every development, the focus is targeted to the combination of strength, stiffness and lightweight with the question how to increase every single value of the combination by using one of the new material concepts.
The target application is thereby the field of alternative powertrains, especially the application area of electric mobility. Therefore, three different concept ideas are given for this strategic part of automotive development. One element is to use significantly cross-industry innovations to ensure a fast integration combined with reliable experience into this new application field.
Stefan Lindner

BIO-BASED MATERIALS FOR EXTERIOR APPLICATIONS – PROJECT BIOHYBRIDCAR

Abstract
The objective of this work is to evaluate the possible uses of bio-based materials (natural fibres, matrix systems) and hybrid material concepts for sustainable mobility. In the first stage, this has been elaborated for a door frame and door panel of a Porsche Cayman GT 4 Clubsport (981) as a test vehicle. On this demonstrator vehicle, the material concepts optimised in the laboratory for selected components are intensively tested in practice in the VLN racing and their suitability for serial production of various exterior components will be analysed. The holistic view is divided into three main points:
  • Technical evaluation (mechanics, vibration, semi-finished products, design, calculation)
  • Ecology (LCA)
  • Economy (supply chain, availability, production process, processability)
This article is focused on the first results of the technical evaluation for the door frame and gives a first outlook on the ecology and economy aspects for the used materials. As part of the project, various exterior components are manufactured under different weighted aspects that allow the comparison of carbon, natural and, especially, hybrid fibre reinforced plastics, thereby highlighting the specific advantages of different material combinations, e.g. using a combination of flax and carbon fibres for reinforcement. In addition to the technical feasibility in terms of material properties and the processing methods as well as an ecological consideration, in particular the economic feasibility of these materials is considered. The following chapters present the fundamental strategy of the project which is to transfer the results to a sustainable mobility in the future.
Ole Hansen, Christoph Habermann, Hans-Josef Endres

IMPROVING THE DURABILITY OF BIO HYBRID FIBER REINFORCED PLASTICS BY PLASMA TREATMENT

Abstract
Natural fiber-reinforced polymer composites have already been successfully established in various lightweight applications subjected to moderate mechanical stress, e.g. automotive interior. Recently, the development of biobased hybrid composites containing both, natural and high-performance fibers, gained the attention of research institutions and industry. These new composites offer optimized density, mechanical performance, have reasonable cost and low environmental impact. The bio hybrid composites enable utilization of the advantages of cellulose-based and high-performance fibers in the same composite and minimize the limitations of the individual composites. Although this approach seems to be a promising solution for several drawbacks, the deficiency of the approaches to improve the durability of these composites in outdoor applications limits their market penetration.
In this project, a specially developed plasma treatment approach, cascade-atmospheric pressure plasma is being adapted in order to improve the mechanical performance of the biobased (hybrid) composites for the application-oriented use under various environmental conditions, e.g. high humidity absorption and temperature variance. This study presents selected results of this project including the assessment of the plasma treatment of multi-ply textiles and the corresponding influence on the mechanical performance of the composites. UD flax tapes and balanced, more isotropic flax fabrics were treated under various plasma parameters and integrated into a partially biobased epoxy resin via vacuum infusion. The analysis of the textile surface and composite mechanical properties were used for the assessment. It has become evident that the selection of the plasma parameters has a significant effect on the packing density and wettability of the treated textiles. Controversial effects have been observed with regard to the mechanical properties of the composites. An improvement of weathering durability is still remaining.
Florian Bittner, Martin Bellmann, Madina Shamsuyeva, Hans-Josef Endres, Wolfgang Viöl

THE BEST PROPERTIES FROM THERMOPLASTIC AND THERMOSETTING RESINS COMBINED IN FIBER REINFORCED PLASTICS FOR IMPROVED PRODUCTIVITY AND PROPERTIES

Abstract
Structural parts made of fiber reinforced plastics do not play a predominant role in automobile mass production due to the costs associated with storage condition, low level of automation, long processing times and safety and health regulations. The idea was to develop a holistic approach which can solve the problems with understanding the whole process chain from molecule to the finished product and integration in common technical infrastructure. A promising strategy was to create a matrix resin which combines easy processing of thermoplastics with superior mechanical properties of thermosets. The new matrix can pre-applied on all type of fibers. The resulting tack-free prepreg has a long shelf life at room temperature in consequence of phase separation of matrix raw materials which can be eliminated by raising the temperature. The resulting material has high reactivity and can be cured to a thermoset within a few minutes. Individual specification of the material like glass temperature, cure rate and toughness can be adjusted.
Andreas Niepel, Woo Jin Choi, Thomas Kowalik, Andreas Hartwig

FAUST: MATERIAL CHARACTERIZATION OF LOW-COST FOAM MATERIALS UNDER REAL BOUNDARY PROCESS CONDITIONS FOR RTM LARGE-SCALE PRODUCTION

Abstract
The Resin Transfer Molding (RTM) process is the first choice for large-scale production of continuous fiber reinforced composite structures due to its capabilities of industrialization and automation at low price. However, the process is currently limited to monolithic structures. Low-cost and yet powerful foam materials do not seem to be compatible with the manufacturing conditions of the RTM process. Available measuring methods do not sufficiently analyze the foam behavior during processing, so that expensive preliminary manufacturing tests are necessary. The use of high-performance foam material, as known in aerospace applications, is not an alternative due to their high price.
In order to enable the use of low-cost foam materials, it is important to match material and process. For this reason, a simple but highly efficient method based on ultrasonic sensors has been developed and patented by the Institute of Composite Structures and Adaptive Systems at DLR. The Foam Analysis Ultrasound System (FAUSt) enables a quantified property description of foam materials under realistic manufacturing conditions for the first time. Without contact to the sample the time-dependent deformation of foam materials depending on temperature and pressure can be determined. In addition to the material characterization itself, the measurement results benefit primarily the development of efficient, material-adapted impregnation strategies. Also process parameter identification for ideal processing and quality assurance is supported. Furthermore, the data can be used for numerical simulation methods in the early development process.
Mark Opitz, Dominic Bertling, Nico Liebers
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