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With the growing urbanized population, vertical farming becomes indispensable in eradicating hunger and ensuring food security for the future. Food security has become a major challenge for the future owing to the scarcity of land, rising global population, urbanization, and polluted soil and water resources. In this scenario, vertical farming as an innovative food production technology caters increased productivity with limited resources and improved carbon footprint. The review begins with a brief introduction to the concept of vertical farming, its opportunities and implications on the economy, environment, and society as a whole, following with an in-depth qualitative analysis of the cutting-edge innovations/technologies are presented in detail. Contrary to the numerous research focusing on mere analysis of economic viability and statistical analysis, the aim is to introduce real cutting-edge technologies that address the challenges of vertical farms such as lack of technical skills or energy requirements. The recent advances of vertical farms includes construction of outer vertical structure and growing shelves using light weight and transparent polymer composites, engineered and tunable LEDs lightings, 3-D printed and recyclable growing substrates, AI-integrated IoTs for environment control, harvesting materials for renewable energy storage etc. Such material innovations with inclusion of AI and robotics transform automated vertical farming into ‘state of the art’ agricultural technology. Production shelf fabricated using UV cured GBOV-glass fiber composite with 60% transparency can overcome the material weight limitation, corrosion, light obstructions etc. associated with the conventional steel shelves. Replacing non-renewable fossil fuels using renewable energy harvested by carbon dots, fluorescent materials, and perovskite solar cells is recommended to minimize the high capital investments associated with energy as well as to reduce the environmental impact. Smart materials such as phase change materials and thermoresponsive windows control the amount of energy expended whereas smart substrate promotes resource management. Application of the newest technology AI in vertical farming facilitates precise control of environment, early pest detection, automation of farming processes, data-driven decision making and precision agriculture. In short, vertical farms utilizing modern innovations of science and technology caters enhanced productivity, improved quality, reduced cost, resource management and sustainability. Hence, automated and sustainable vertical farms promoting global food security and circularity have the potential to transform into burgeoning technology of future.
Efficient recycling pathway of bio-based composite polyurethane foams via sustainable diamine
(2024)
Aminolysis is widely recognized as a valuable chemical route for depolymerizing polymeric materials containing ester, amide, or urethane functional groups, including polyurethane foams. Bio-based polyurethane foams, pristine and reinforced with 40 wt% of sustainable fillers, were depolymerized in the presence of bio-derived butane-1,4-diamine, BDA. A process comparison was made using fossil-derived ethane-1,2-diamine, EDA, by varying amine/polyurethane ratio (F/A, 1:1 and 1:0.6). The obtained depolymerized systems were analyzed by FTIR and NMR characterizations to understand the effect of both diamines on the degradation pathway. The use of bio-based BDA seemed to be more effective with respect to conventional EDA, owing to its stronger basicity (and thus higher nucleophilicity), corresponding to faster depolymerization rates. BDA-based depolymerized systems were then employed to prepare second-generation bio-based composite polyurethane foams by partial replacement of isocyanate components (20 wt%). The morphological, mechanical, and thermal conductivity properties of the second-generation polyurethane foams were evaluated. The best performances (σ10 %=71 ± 9 kPa, λ = 0.042 ± 0.015 W∙ m-1 ∙K-1) were attained by employing the lowest F/A ratio (1:0.6); this demonstrates their potential application in different sectors such as packaging or construction, fulfilling the paradigm of the circular economy.
A review, with 32 refs., of various new proposals for recycling and reusing of wind turbine blades by small companies (including the Polish Anmet company). New projects on shredding blades as well as on architecture objects, road construction, geotechn. blocks, floating platforms and observation towers were presented. Prodn. of composite chipboard panels and recovery of carbon fibers by waste pyrolysis were also included.
Carbon fiber-reinforced plastic (CFRP) components are known for their exceptional resilience and ultra-lightweight nature, making them the preferred choice for applications requiring high mechanical loads with minimal weight. However, the intricate and anisotropic structure of CFRP components poses challenges, resulting in expensive repairs and testing. This complexity also leads to increased waste generation. Yet, innovative recycling processes offer a solution by reintegrating carbon components into a closed material cycle, promoting sustainability and circular economy principles. This work focuses on recycled CFs (rCFs) obtained through a continuous recycling method for CFRP primary recyclate from composite pressure vessel. Furthermore, re-purposing of the separated matrix material for secondary energy sources makes the process, a 100% recycling route. This closed-loop approach addresses conventional pyrolysis challenges and contributes to more efficient utilization of CFRP waste components. rCF and recycled polyethylene terephthalate (rPET) polymers were compounded through an extrusion process. Test specimens were then fabricated according to standard test norms to evaluate the resulting tensile and bending properties. The tensile and flexural modulus of the rCF-rPET obtained are 6.80 and 4.99 GPa, respectively. The need for enhancing the quality of rCF is apparent. Suggestive and potential implications and the marketability of rCF-rPET compounds are also discussed.
Dieser Beitrag stellt eine Entwicklung, Anpassung und Untersuchung der neuartigen Pinschweißtechnik zur Verbindung thermoplastischer Faserkunststoffverbunde mit metallischen Fügepartnern dar. Die untersuchte Fügetechnik bietet, im Vergleich zu anderen Verfahren, neben einer einseitigen Zugänglichkeit, ein hohes Leichtbaupotenzial. An Multimaterial-Einzelpinverbindungen wurden die CMT-Pinschweißbarkeit charakterisiert und unterschiedliche Fügestrategien erprobt und ausgewertet. Als Bewertungskriterien wurden das Schweißgut sowie der Faser- und Matrixerhalt in Abhängigkeit von den Schweißparametern untersucht. Die mechanische Beanspruchbarkeit der mit dem entwickelten Verfahren erstellten Verbindungen wurde in Scherzugversuchen ermittelt. An Mehrpinverbindungen wurde anschließend der Einfluss der Pinanordnung untersucht und die Auslegung der Fügezone analysiert. Der Fügeprozess wurde an Funktionsmustern und diese wiederum in 3-Punkt-Biegeversuchen validiert sowie mit dem Kleben verglichen.
Modern material-compatible joining methods for fiber-reinforced plastics require the heating of the materials. In order to predict the respective complex temperature fields and curves, the Fraunhofer IAP and the BTU
Cottbus-Senftenberg have developed numerical methods, which are able to simulate different radiation sources and process sequences as well.
Fiber-reinforced plastics (FRP) offer great lightweight construction potential. However, the anisotropic high-performance materials can only be fully utilized through the development of material-specific joining processes. A literature study shows that conventional methods such as screwing, riveting and bolting are unsuitable, since the load-bearing fibers are severed in the joining region. This leads to high-stress concentrations. To reduce these, a method is presented in which through holes are created in thermoplastic FRP by reorienting the fibers in this area around the point of disruption in accordance with the load path. For this purpose, the polymer matrix is softened locally by applying heat and penetrated with a needle or mandrel. Based on this, a technology for material-specific joining of FRP and metals has been developed in the form of thermomechanical flow drill joining. In this process, a mandrel forms a bush from the metal component and deflects the fibers of the locally softened organic sheet to suit the material. Cold metal transfer (CMT) pin welding is presented as another fully automatable joining process. In this method, the softened plastic component is penetrated with the welding wire, displacing the fibers in the joining area and realigning them to suit the load path.
Neuartige, werkstoffgerechte Fügeverfahren für Faserkunststoffverbunde setzen die Erwärmung der Materialien voraus. Um die damit verbundenen komplexen Temperaturfelder und -verläufe vorherzusagen, haben das Fraunhofer IAP und die BTU Cottbus-Senftenberg numerische Verfahren entwickelt. Mit diesen können auch verschiedene Strahlungsquellen und Prozessabläufe simuliert werden.
Carbon fiber reinforced plastics (CFRP) owing to its excellent properties have found its extensive application in various fields ranging from medical to automobile and aerospace industries. This has thereby led to ever-increasing demand of carbon fiber production and as well as resulting in tonnes of carbon fiber wastes in the landfills [5]. Due to the high positive impacts of using carbon fibers, the energy intensive and cost intensive production of virgin fibers and the growing landfills are often overlooked. Hence, the need for recycling and repurposing of carbon fiber wastes have gained the significance at present day. Although various recycling technologies have been developed yet, various challenges are faced with processing of recycled carbon fibers (rCF). Besides, the desired application specific properties are not compromised for high cost and high-energy requirement. Therefore, an overall development of processing rCF is sought from not only
a sustainability point but also an economic point. Various efficient recycling technologies are currently operating. The challenges arises in commercializing the recycled fibers after the recycling process. The recycled fibers often require various post-processing of fibers and
undergoes fiber degradation. This induces a skeptical mindset for the buyers to introduce the recycled fibers in the material ecosystem. This paper currently discusses the processing challenges of long rCF in a compounding plant. To form a closed loop, the recycled fibers
are obtained from the novel thermocatalytic degassing process from the CFRP recycling pioneers in Germany, Global EnerTec AG, Guben. This plant in Guben not only recycles carbon fibers from automotive CFRP wastes but also repurposes the epoxy matrices into secondary energy sources. This paper focuses in investigating the processing of rCF obtained from a 100% recycling technology. The aim is to investigate the possible technical challenges so that the rCF can be repurposed to new product manufacturing. Thereby, addressing the concerns with the development of closed loop circular economy in recycling CFRP wastes.
Durch den strukturellen Einsatz von Faser-Kunststoff-Verbunden (FKV) lassen sich hochwertige gewichtsoptimierte Karosserien in Mischbauweise umsetzen. Die untersuchte CMT-Pin-Schweißtechnik zur Verbindung von thermoplastischen Organoblechen mit Stählen bietet, im Vergleich zu anderen Verfahren, neben einer einseitigen Zugänglichkeit, ein hohes Leichtbaupotenzial. Das Vorhaben wurde auf eine werkstoff-, prozess- und konstruktionsgerechte Umsetzung des Verfahrens ausgerichtet.
Auf Basis experimenteller und numerischer Untersuchungen wurde eine Methode zum Vorwärmen von Organoblechen mittels Infrarotstrahlung entwickelt. Die Eignung der CMT-Pin-Technologie wurde sowohl für das Fügen von karbon- als auch glasfaserverstärktem PA6 betrachtet. Als Bewertungskriterien wurden das Schweißgut sowie der Faser- und Matrixerhalt in Abhängigkeit der Schweißparameter untersucht. Das entwickelte Verfahren wurde mit herkömmlichen Fügemethoden bzgl. der in Kopf- und Scherzugversuchen ermittelten Festigkeiten verglichen. Zur Bestimmung der Beständigkeit der Verbindungen gegen unterschiedliche Witterungsbedingungen wurden Salzsprühnebel- und Wechselkorrosionstests durchgeführt. Mit dem Fügen von Hutprofilen wurde die Anwendung der entwickelte CMT-Pin-Technik am Tunnel sowie den Längs- und Querträgern der Bodenstruktur eines Kraftfahrzeugs demonstriert.
In der Automobilindustrie spielt bei der Herstellung von schalenförmigen Faserverbundkomponenten mit komplexer Geometrie das Resin-Transfer- Moulding-Verfahren (RTM) eine bedeutende Rolle. Um Verschnitt sowie Umformgrad zu reduzieren werden geometrisch komplexe, großflächige Strukturen aus einzelnen Sub-Preforms zusammengesetzt. Während der Preform-Montage entstehen im Überlappungsbereich des Bauteils Wanddickensprünge sowie lokale Abweichungen vom gestreckten Faserwinkel. Der textile Fügebereich der Sub-Preforms ist nicht nur für die mechanischen Eigenschaften eines Bauteils ausschlaggebend, sondern hat auch direkten Einfluss auf das Füllverhalten bei der Bauteilherstellung im RTM-Prozess. Ziel dieser Arbeit ist die Entwicklung flexibler, werkstoff- und prozessgerechter Preforms für hochbeanspruchte Faserverbund-Komponenten im Automobilbau. Textilien welche mit dem TFP-Verfahren hergestellt werden erfüllen die Anforderungen der Großserie bei Gewährleistung der Richtungsflexibilität. Diese Arbeit bietet Lösungen für eine gekoppelte Drapier- und Füllsimulation von lastpfadgerechten technischen Gesticken, sowie einen Abgleich mit experimentell gewonnenen Erkenntnissen. Prozessrelevante Parameter, wie Spaltabstände und Überlapplängen werden analysiert, bewertet und gegenübergestellt. Erkenntnisse bzgl. dem Einfluss von Drapierprozessen auf das Füllverhalten werden ermittelt und mit den Auswirkungen dieser Überlappungen auf die mechanischen Eigenschaften verknüpft.
The European Parliament and Council has defined a mandatory specific emission target of 95 g CO2/km by 2020 for passenger cars. Vehicle weight is a significant factor contributing to fuel consumption. Reducing the weight of the vehicle can be one promising option for decreasing CO2 emissions, which becomes a top priority for the automotive industry. In this research, two approaches were used to address the need. One involved developing structural parts using fibre reinforced plastics (FRP), and the other involved designing and developing FRP–metal hybrid laminates, which were constructed by reinforcing FRP locally to the metal surface. Existing joining techniques such as riveting, bolting, adhesive joining, ultrasonic welding, and flow drill joining techniques require additional processing steps to perform the joining, which could considerably increase processing time, cost, and energy expenditure. The present work describes a method to join FRP and metals using the adhesion strength of the investigated polymers. The developed FRP–metal hybrid laminates combine the advantages of metal and FRP together. Steel hot-stamping is known to yield very high strength. Fibre reinforced plastic–metal hybrid laminates were developed using hot stamped steels to transfer their superior mechanical properties to the final structure. To utilize the complete lightweight potential of thermoset and thermoplastic polymers, FRPs and FRP–metal hybrid laminates were developed using both the polymers. Along with this increased demand for FRP structures, there is growing interest in a repair technique in the automotive industry. The second objective of this thesis consists of designing and developing a new repair technique, which regains the strength and stiffness properties of the damaged part. The existing scarf repair technique is not suitable for thin laminates, which have limited access to the damaged area. Perforation damages were introduced into the FRP structures using a low-velocity impact load. A modified injection repair technique is used to repair these damaged FRP structures. Non-destructive techniques were utilized to understand the damage and the effectiveness of the repair.
Powders are typical starting materials for the production of ceramics. In this paper, a strategy is presented, that allows a quick quality control of inorganic powders. This strategy bases on dyes. Dye adsorption as well as the usage of indicators allow an easy and cheap characterisation of powders. Furthermore, the tests provide information on the chemical behaviour of the powders. It can be shown, that there is a coherence between the results of colour tests of a powder and the influence on the properties of ceramics
(prepared from this powder). Ceramic powders suffer from perpetual changes mainly by two reasons. First, due to their large surface
powders show interactions with components of the atmosphere (e.g. water, carbon dioxide, oxygen). A further problem arises, if natural sources are the origin of powders: The material can have tremendous
changes in the chemical composition causing serious problems in the production of ceramics. That’s why quality control of powders is a must. Unfortunately, the methods used are expensive and time consuming
(e.g. BET, EDX, XPS, ICP). In particular, smaller companies have only limited opportunities to control the quality of their starting powders. In this paper a simple, quick and inexpensive method is suggested, which bases on dyes and allows a control of powder quality.
Preforms with large complex geometry, for example, body parts for the automotive industry, are consisted into multiple elements – so-called sub-preforms. Hereby the sub-preforms can be adjusted to different local load cases but joining of these sub-preforms also raises challenges. The preform joints are decisive to the mechanical properties of the final component. The state-of-the-art joint, a single lap, results in a variation of wall thickness with local redirection of fibre orientation. In this paper, the influence of alternative joints of embroidered fabrics is analysed regarding the resulting mechanical properties of the part. The built test specimen contains different preform joints with different process-relevant parameters. Such as gaps between the sub-preforms, to analyse the influence on the mechanical performance. To reveal the various defects like voids, air pockets and to validate the fibre orientation, computer tomography (CT) investigation was performed on the built plates. In addition, the influence in mechanical properties was also analysed. The overlapping is analysed with tensile strength test according to DIN EN ISO 527-4.
In this paper the relationship between surface energy and flexural strength of metal laminate made by reinforcing glass fibre reinforced polymer on steel surfaces was investigated. Sand blasting was performed on 22MnB5 steel surface. This steel was stacked together with layers of unidirectional glass/polyamide-6 prepreg, followed by pressing in a hot press. Influenced parameters are pressure, temperature and time. 3D profilometer analysis was used to investigate the roughness profile on the surface of the steel generated by the sand blasting. The surface energy of the steel surface was calculated from a set of contact angles measured by three different liquids. To identify the optimal surface treatment, the variation of surface energy, flexural strength and roughness of the steel surface was determined as function of the surface treatment. Surface roughness (Ra of 1.08 μm), results indicate that increasing surface roughness leads to improvement in flexural modulus. The increase further leads to decrease in flexural modulus. In addition, the influence of surface energy and flexural strength on the impact damage behaviour was investigated too. The results showed that the sample with highest flexural modulus had the lowest impact-induced damage area.
At present plywood structures are used in the loading area of utility structures. Low velocity impact studies on these structures showed cracks on its lower surface. Hence, in the current study low-velocity impact of a lighter honeycomb sandwich structure is investigated to satisfy the needs of the utility vehicle segment. To meet this objective, facing sheets are manufactured using the polypropylene matrix and glass fibers. Polypropylene honeycombs are used in the study. Depending on the experimental boundary conditions, a cross-ply laminate set up is used for the facing sheets. An impact energy of 100 J is chosen in the study. This energy caused visible failure on the plywood sample. Hence a lighter sandwich construction which can resist 100 J impact is implemented in this study. Influence of top and bottom facing sheet thicknesses on the amount of damage inflicted on its surfaces are studied. Experimental histories of absorbed energy and contact force are recorded. A finite element analysis is performed using LS-DYNA and numerical results are compared with the experimental responses. A honeycomb sandwich panel [0/90/90/0/Core/0/90/90/0] meeting the objective of the study is seen as an optimum replacement for the existing plywood structures.
This study aims to investigate the low-velocity impact response and post-impact flexural behaviour of glass/polyamide-6 (G/PA-6) composite. G/PA-6 composites with a layup configuration of [02,902]s were prepared via press-forming technique. Composite samples were developed using four different processing conditions, by modifying compression pressure and heating temperature. Local variations of fiber volume and porosity fraction were noticed for samples developed in each processing conditions. On the investigated samples, damages were induced by using 35 joule of drop weight impact to investigate the impact resistance of samples with respect to different processing conditions. The damage behaviour and residual flexural strength was characterized using a micro-CT and three-point bending tests respectively. Furthermore, the influence of porosity fraction on the residual flexural strength were investigated. This paper will provide necessary fundamental knowledge for future selection of processing parameters in order to have enhanced impact performance.
Organic sheets made of fiber-reinforced thermoplastics can make a crucial contribution to increase the lightweight potential of a technical design. They show high specific strength- and stiffness properties as well as good damping characteristics, while being able to show a higher energy absorption capacity than comparable metal constructions. In addition, organic sheets provide good recycling capabilities. Nowadays, multi-material designs are an established way in the automotive industry to combine the benefits of metal and fiber-reinforced plastics (FRP). Currently used technologies for the joining of organic sheets and metals in large-scale production are mechanical joining and adhesive technologies. Both require large overlapping areas to achieve the desired joint strength and stiffness of the technical design. Additionally, mechanical joining is usually combined with “fiber-destroying” pre-drilling and punching processes. This will disturb the force flux at the joint zone by causing unwanted fiber- and inter-fiber failure and inducing critical notch stresses. Therefore, the multi-material design with fiber-reinforced thermoplastics and metals needs optimized joining techniques that don’t interrupt the force flux, so that higher loads can be induced and the full benefit of the FRP material can be used. This article focuses on the characterization of a new joining technology, based on the Cold Metal Transfer (CMT) welding process, that allows to join organic sheets and metals in a load path optimized design. This is achieved by realigning the fibers around the joint zone by the integration of a thin metal pin. The alignment of the fibers will be similar to load paths of fibers inside structures found in nature. A tree with a knothole is always going to align its fibers in principle stress direction. As a result of the bionic fiber design, high joining strengths can be achieved. The increase of the joint strength compared to blind riveting was performed and proven with stainless steel and orthotropic reinforced composites in tensile shear-tests, based on the DIN EN ISO 14273.
Composite materials have gained popularity in automotive industries due to its lightweight potential, good damping behaviour as well as high strength and stiffness properties. Based on the increase in usage of composites, there is a growing interest for a repair technique in the automotive industry. Along with these raise in
demand there comes a need for an all-inclusive review article and the objective of this article is to address this need. Two repair techniques, namely scarfing repair and injection repair, have the potential to be used in automotive industry. This paper compiles the various research work done in this field of repairing along with
various processing steps associated with it. Further this paper reviews the non-destructive technique that can be used for damage identification and repair assessment.
The current trend shows an increasing demand for composites due to their high stiffness to weight ratio and the recent progress in manufacturing and cost reduction of composites. To combine high strength and stiffness in a cost-effective way, composites are often joined with steel or aluminum. However, joining of thermoset composite materials is challenging because circular holes are often used to join them with their metal counterparts. These design based circular holes induce high stress concentration around the hole. The purpose of this paper is to focus on layup configuration and its impact on notch stress distribution. To ensure high quality and uniformity, the holes were machined by a 5 kW continuous wave (cw) CO2 laser. The stress distribution was evaluated and compared by using finite element analysis and Lekhnitskii’s equations. For further understanding, the notch strength of the laminates was compared and strain distributions were analyzed using the digital image correlation technique.
Composite structures used in modern engineering applications are often subjected to circular holes in order to join with metal components via riveting, bolting or pinning joints. These design based holes will interrupt the force flux in the direction of the fibers and create high stress concentrations near the notched area. Objective of the project is to understand the quality of the quasi-isotropic composite laminates ([45°, -45°, 0°, 90°]S) containing circular hole. To achieve this objective, a 3-phase portal milling machine and a 5kW continuous wave (cw) CO2 laser system were used to produce the circular holes in the composite laminates. The processing parameters for both the processes are varied to understand its influence. The quality of the circular hole produced
by these methods are further investigated and compared in order to arrive at the optimum processing parameters for the given quasi-isotropic composite laminates. The hole qualities were evaluated by means of delamination factor caused by milling; cone angle, matrix
evaporation for cw-CO2 laser system. For further comparisons, the optimal parameter combinations of both methods were selected for a tensile test according to the standard ASTM D5766-2002.
Organic sheets made out of fiber-reinforced thermoplastics are able to make a crucial contribution to increase the lightweight potential of a design. They show high specific strength- and stiffness properties, good damping characteristics and recycling capabilities, while being able to show a higher energy absorption capacity than comparable metal constructions. Nowadays, multi-material designs are an established way in the automotive industry to combine the benefits of metal and fiber-reinforced plastics. Currently used technologies for the joining of organic sheets and metals in large-scale production are mechanical joining technologies and adhesive technologies. Both techniques require large overlapping areas that are not required in the design of the part. Additionally, mechanical joining is usually combined with “fiber-destroying” pre-drilling and punching processes. This will disturb the force flux at the joining location by causing unwanted fiber- and inter-fiber failure and inducing critical notch stresses. Therefore, the multi-material design with fiber-reinforced thermoplastics and metals needs optimized joining techniques that don’t interrupt the force flux, so that higher loads can be induced and the full benefit of the FRP material can be used. This article focuses on the characterization of a new joining technology, based on the Cold Metal Transfer (CMT) welding process that allows joining of organic sheets and metals in a load path optimized way, with short cycle times. This is achieved by redirecting the fibers around the joining area by the insertion of a thin metal pin. The path of the fibers will be similar to paths of fibers inside structures found in nature, e.g. a knothole inside of a tree. As a result of the bionic fiber design of the joint, high joining strengths can be achieved. The increase of the joint strength compared to blind riveting was performed and proven with stainless steel and orthotropic reinforced composites in shear-tests based on the DIN EN ISO 14273. Every specimen joined with the new CMT Pin joining technology showed a higher strength than specimens joined with one blind rivet. Specimens joined with two or three pin rows show a higher strength than specimens joined with two blind rivets.
Multi-layer constructions become more and more relevant in lightweight applications due to their high strength to
weight ratio. They offer excellent crash, damping and recycling properties. Also, the morphology of thermoplastic
carbon fibre reinforced plastics (CFRP) render them interesting for large scale manufacturing processes.
Nevertheless, a major disadvantage results in a poor resistance against wear and tear, e.g. erosion, which is
attributed to weak hardness properties. Hence, this work deals with tribological investigations on orthotropic
carbon fibre reinforced polymers (PA 6) either with protective ceramic coating or without. The chosen coating
system is a well-known protective covering of metal components, e.g. metal cutting tools, produced by physical
vapor deposition (PVD). To characterize the coating system on thermoplastic CFRP, standard analyzing methods are utilized, like optical and scanning electron microscopy (SEM). The tribological investigations are conducted by the tribological ball on disk method to generate wear tracks on the sample surfaces and hence to calculate the
wear rates. These results are compared to literature findings with respect to a certain protective coating system (TiN) and a second nano-structured gel coating system, where both systems are deposited on a thermosetting
material, i.e. carbon fibre reinforced epoxy resin, respectively. For this purpose the feasibility of depositing a protective ceramic layer on thermoplastic CFRP is demonstrated. First results on suitable surface pre-treatments have shown a significant influence on the coating quality. The improved performance regarding the wear behavior with respect to tribology compared to the poor substrate and existing technologies is shown additionally.
The current trend shows an increasing demand for novel technologies, that facilitate a functional integration of fiber reinforced polymers (FRP) in metal based structures, especially in automotive industry. To comply with the requirements of large-scale production the use of fiber reinforced thermoplastics in form of hybrid metal/composite-laminates seems advantageous. By targeted exploitation of their high lightweight potential, combined with suitable capabilities for mass production and good damping properties, cost-effective and weight-optimized parts with high stiffness and load capacity can be provided for future applications.
As there is little known about the processing and the mechanical properties of thermoplastic based FRP/metal-laminates, the study focuses on the development of novel hybrid laminates with low residual stresses, made of metallic steel sheets and continuous glass or carbon fiber reinforced polyamide 6. In this context, the influence of several pre-operations like sand blasting, cleaning or primer application on the interlaminar shear strength (ILSS) was examined in addition to their resistance to cathodic dip paint treatment.
Im Rahmen des DFG-AiF-Clustervorhabens »Großserientaugliche Prozessketten für hochintegrierte Bauteile aus hybriden Faser-Kunststoff / Metall-Verbunden« beschäftigt sich das Fraunhofer IWU, die TU Chemnitz und das IFUM mit der Entwicklung großserienfähiger Prozessketten zur effizienten Verarbeitung von Faser-Kunststoff / Metall (FK/M)-Verbunden zu konturierten Werkstücken, insbesondere unter Berücksichtigung der Anforderungen aus der Automobilindustrie. Dazu werden zwei grundlegende serienfähige Prozessketten für die Fertigung profilierter Bauteile entwickelt: Bei der Prozesskette 1 werden ebene FKM-Verbunde, bestehend aus optimiertem thermoplastischen Faser-Kunststoff und dünnwandigen Metalldecklagen, thermisch unterstützt zu profilierten Strukturbauteilen umgeformt. Die Prozesskette 2 behandelt eine neue Prozessvariante, bei der während der gemeinsamen Umformung von thermoplastischen Faser-Kunst¬stoff-Verbunden und metallischen Blechen die Verbindung der Einzelwerkstoffe zu hybriden Strukturen prozessintegriert erfolgt. Bei der Technologieentwicklung wird die gesamte Prozesskette von der Temperierung der Materialien über das Handling der Einzelkomponenten bis hin zur Umformung und Abkühlung der Teile unter Druckbeanspruchung betrachtet. Für diese Prozesskette wird ein Werkzeug ausgelegt und unter seriennahen Bedingungen umgesetzt. Die Machbarkeit beider Prozessvarianten wird an einem Technologiedemonstrator nachgewiesen und hinsichtlich der Prozessfähigkeit und der Verfahrensgrenzen miteinander verglichen.
Als branchenspezifischer Technologiedemonstrator wurde gemeinsam mit den projektbegleitenden Firmen der Dachquerträger einer PKW-Karosserie ausgewählt. An der fertiggestellten Komponente werden die mechanischen Bauteileigenschaften bei statischer Belastung geprüft. Ziel ist die Bewertung des Einsatzpotentials der untersuchten FK/M-Verbunde in Karosseriestrukturen von PKWs unter Leichtbaugesichtspunkten. Auf Basis des erarbeiteten Prozess-Know-hows können die Prozesszeiten und -kosten belastbar kalkuliert werden. Damit steht der Industrie zum Abschluss des Verbundprojekts ein umfassendes Instrument zur prozessorientierten Bauteilauslegung, Technologieplanung und Kalkulation anwendungsbereit für die Serienfertigung zur Verfügung.
Carbon fibre reinforced thermoplastics (CFRP) are intensively used in lightweight
applications due to their high strength to weight ratio. In addition they offer good crash,
damping and recycling properties. On the basis of their morphology they are suitable for large
scale manufacturing processes. A major disadvantage consists of its poor hardness properties,
which is again an important requirement to realize a good erosion and wear behaviour.
Design/methodology/approach: In this work the application of orthotropic carbon
fibre reinforced polymers (PA6), with protective TiAlN coatings, produced by physical
vapor deposition (PVD), is investigated. The characterization of the coating is performed
by nanoindentation tests, roughness measurements and scanning electron microscopy.
Furthermore micro hardness tests on selected well prepared cross sections are conducted,
to compare the coating quality with established coating systems.
Findings: By applying TiAlN coating, the hardness of the CFRP samples can be increased
substantially up to 15 GPa, in comparison to the basic substrate. In addition the quality of
the coating surface can be improved significantly by plasma etching pre-treatment.
Research limitations/implications: The presented findings are preliminary results to
prove the application of a standard processed ceramic coating on new composite types
for mass production. The PVD coating process as well as the utilized testing methods are
suitable to realize hard coatings on thermoplastic CFRP. This effect can be exploited for
several lightweight applications to increase the erosion and wear resistance of composite
materials.
Originality/value: The presented results show, that ceramic coatings can be deposited
on standard thermoplastic CFRP with polyamide 6 matrix. Therewith it can be expected,
that the PVD coating process can make a essential contribution to increase the range of
applications.
Als Teil des DFG/AiF-Clusters „Großserientaugliche Prozessketten für hochintegrierte Bauteile aus hybriden Faser-Kunststoff / Metall-Verbunden“ erfolgte im AiF-Projekt 17688 BR/1 die methodische Entwicklung von großserientauglichen Bauweisenkonzepten für Hybridstrukturen aus thermoplastbasierten Faser-Kunststoff/Metall-Verbunden (FK/M-Verbunden) im Fahrzeugbau sowie die Erarbeitung von belastungsgerechten Krafteinlei-tungsbereichen zur Integration der neuartigen Bauteile in metallische Strukturen. Die Pro-jektergebnisse wurden in Form von drei generischen Technologiedemonstratoren am Beispiel von hybriden Pkw-Dachquerträgern veranschaulicht. Dabei wurden zwei Demonstratoren aus FK/M-Verbunden mit Stahl- (HC220Y+ZE, t = 0,25 mm) bzw. Aluminiumdeckschichten (EN AW 5182, t = 0,2 mm) und ein Faser-Kunststoff-Verbund-Dachquerträger (Kohlenstofffaserverstärktes Polyamid 6) mit metallischen Lasteinleitungselementen (HC260LAD+Z100 bzw. AA5754-W, t = 1,0 mm) konzipiert.
Im Vergleich zu einer Referenzgeometrie in Stahlbauweise (t = 1,0 mm) konnte bei ver-gleichbaren Steifigkeitseigenschaften eine Masseeinsparung von bis zu 55% mit FK/M-Verbunden und etwa 64% in Faser-Kunststoff-Verbundbauweise prognostiziert werden. Die simulativ ermittelten Ergebnisse werden in Teilprojekt 5 des Clusters experimentell validiert.
Im Hinblick auf eine werkstoffgerechte Anbindung der stark anisotropen Bauteile an metallische Grundstrukturen wurden Untersuchungen zum Thermomechanischen Ausformfügeverfahren (TAF) und dem Kleben mittels 2K-Epoxid- und 2K-Polyurethanklebstoffen durchgeführt. Anders als bei etablierten Verfahren aus dem Metallbau, wie dem Nieten, Clinchen oder Schrauben, die auf spanend gebohrten Durchgangslöchern im Faser-Kunststoff-Verbund oder Fügeelementen mit Schneidanteil basieren, findet bei den untersuchten Verfahren keine Schädigung der Faserstruktur statt.
Die Ergebnisse aus Kopf- und Scherzugversuchen nach DIN EN ISO 14272 und DIN EN ISO 14273 zeigen eine prinzipielle Eignung des TAF-Verfahrens, sowohl für die Verbindung von FK/M-Hybridlaminaten, als auch FKV mit Metall. In Zugscherprüfungen nach DIN EN 1465 wurde der Einfluss verschiedener Vorbehandlungsmaßnahmen auf die Haftfestigkeit der geklebten Zugscherproben ermittelt. Dabei erwies sich insbesondere die Kombination aus Korundstrahlen und Beflammen mittels Flammenpyrolyse als zielführend.
Nach Ermittlung der benötigten Kennwerte wurde eine Simulations- und Auslegungsstrategie für kraftflussgerechte Fügepunkte am Beispiel von thermomechanisch gefügten Verbindungen vorgestellt. Aufgrund der anisotropiespezifischen, inhomogenen dreidimensionalen Spannungszustände in der Umgebung von FKV-Fügezonen wird eine schnittreaktionsbezogene Methodik zur Auslegung von FK/M-Fügezonen empfohlen. In Verbindung mit einer entsprechenden Versagenshypothese erlaubt diese auf Basis von einfachen Fügepunkt-Ersatzmodellen eine einfache ingenieurmäßige Analyse des Fügepunktversagens durch Auslesen der Schnittreaktionen.
Des Weiteren wurden in Zusammenarbeit mit TP5 zwei Prozessvarianten zur fertigungs-technischen Umsetzung der hybriden Dachquerträger aufgestellt. In ersten Vorversuchen konnte daran bereits die Herstellung erster Demonstratoren erfolgreich durchgeführt wer-den, die im Rahmen des 35. EFB-Kolloquiums am 25.03.2015 in Bad Boll sowie im EFB-Arbeitskreis Hybride Strukturen am 21.01.2015 in Dresden und 17.06.2015 in Rostock vorgestellt wurden.
Das Ziel des Forschungsvorhabens wurde erreicht.
Das IGF-Vorhaben „Bauweisenkonzepte und Auslegung von Krafteinleitungsbereichen bei Hybridstrukturen aus Faser-Kunststoff/Metall-Verbunden im Fahrzeugbau“ wurde im Rahmen des AiF/DFG-Clusters „Großserientaugliche Prozessketten für hochintegrierte Bauteile aus hybriden Faser-Kunststoff/Metall-Verbunden“ unter der Fördernummer AiF 17688BR/1 von der Forschungsvereinigung EFB e.V. finanziert und betreut und über die Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF) im Rahmen des Programms zur Förderung der industriellen Gemeinschaftsforschung und -entwicklung (IGF) vom Bundesministerium für Wirtschaft und Technologie aufgrund eines Beschlusses des Deutschen Bundestages gefördert. Der Abschlussbericht ist als EFB-Forschungsbericht Nr. 417 erschienen und bei der EFB-Geschäftsstelle und im Buchhandel erhältlich.
Multi-material-design (MMD) is commonly realized through the combination of thin sheet metal and fibre reinforced plastics (FRP). To maximize the high lightweight potential of the material groups within a multi-material system as good as possible, a material-adapted and particularly fibre adjusted joining technology must be applied. The present paper focuses on two novel joining technologies, the Flow Drill Joining (FDJ) method and Spin-Blind-Riveting (SBR), which were developed for joining heavy-duty metal/composite hybrids. Tests were carried out with material combinations which are significant for lightweight constructions such as aluminium (AA5083) and carbon fibre-reinforced polyamide in sheet thickness of 1.8 mm. The mechanical testing and manufacturing of those multi-material joints was investigated.
Prozessketten zur Herstellung und Integration von naturfaserverstärkten Hochleistungskunststoffen
(2015)
Thermoplastic fiber reinforced/metal-hybrid laminates for structural lightweight applications
(2015)
Reliable line production processes and simulation tools play a central role for the structural integration of thermoplastic composites in advanced lightweight constructions. Provided that material-adapted joining technologies are available, they can be applied in heavy-duty multi-material designs (MMD). A load-adapted approach was implemented into the new fully automatic and faulttolerant thermo mechanical flow drill joining (FDJ) concept. With this method it is possible to manufacture reproducible high strength FRP/metal-joints within short cycle times and without use of extra joining elements for the first time. The analysis of FDJ joints requires a simplified model of the joint to enable efficient numerical simulations. The present work introduces a strategy in modeling a finite-element based analogous-approach for FDJ-joints with glass fiber reinforced polypropylene and high-strength steel. Combined with a newly developed section-force related failure criterion, it is possible to predict the fundamental failure behavior in multi-axial stress states. The functionality of the holistic approach is illustrated by a demonstrator that represents a part of a car body-in-white structure. The comparison of simulated and experimentally determined failure loads proves the applicability for several combined load cases.
The development of a new joining technology, which is used to manufacture high strength hybrid constructions with thermoplastic composites (FRP) and metals, is introduced. Similar to natural regulation effects at trees, fibers around the FRP joint become aligned along the lines of force and will not be destroyed by the joining process. This is achieved by the local utilization of the specific plastic flow properties of the FRT and metal component. Compared with usual joining methods—such as flow drill screws, blind and self-piercing rivets—noticeably higher tensile properties can be realized through the novel process management. The load-bearing capability increasing effect could be proved on hybrid joints with hot-dip galvanized steel HX420LAD and orthotropic glass—as well as carbon—fiber reinforced plastics. The results, which were determined in tensile-shear and cross-shear tests according to DIN EN ISO 14273 and DIN EN ISO 14272, are compared with holding loads of established joining techniques with similar joining point diameter and material combinations.
Der Trick: CFK statt Stahl
(2013)