This contribution presents a methodology for designing, manufacturing, and testing of a multi-material solution demonstrator of a lower control arm for electric vehicle (EV) chassis made of a three-dimensional Fiber reinforced polymer-Metal Laminate (FML). The Integrated Computational Materials Engineering (ICME) approach includes simulation methodology for process modeling, i.e. forming and draping, and part performance with the aim to reduce the developing time and related trial and errors. The challenges, besides a limited availability of resources and material input data for numerical models, include the combination of different forming methods for Glass Fiber Reinforced Polymers (GFRP) and sheet metals (aluminum alloy) with the aim of simultaneous forming of both materials. Especially the sheet metal forming needed several improvement steps regarding heat treatment state to increase the ductility and reduce crack propagation, as well as optimization of the shape of the blanks to be formed into an asymmetric, three-dimensional geometry. Assembly includes adhesive bonding of the flat FML to the curved structure, and adapters for the testing to be performed. The quasi-static misuse testing is in good agreement to the results obtained from the simulated structural performance, with the weakest location being the adhesive bond line. An outlook on potential improvements regarding process simulation for manufacturing Fiber Metal Laminates, including necessary input data, is provided. 

This paper aims to define the challenges and requirements necessary for the holistic management of wind turbine blades at the end of their service (EoS). Conducted within the Swedish research project Circublade, this study focuses on Sweden, although many challenges and findings are applicable to other countries. Various alternatives for managing EoS wind turbine blades exist at different levels of market maturity, but this paper specifically focuses on repurposing the blades into new products. The development of three concept designs—short-span pedestrian bridges, façade elements for building applications, and noise barriers for roads and railways—has been explored, along with aspects related to material sourcing, logistics, and implementation. For material sourcing, a digital platform containing blade data and tools to facilitate repurposing has been developed. An environmental evaluation of the different concepts highlights the significant impact of transportation on the overall environmental footprint, underscoring the necessity of a holistic approach to managing EoS blades.

In response to global challenges in resource supply, many industries are adopting the principles of the Circular Economy (CE) to improve their resource acquisition strategies. This paper introduces an innovative approach to address the environmental impact of waste Glass Fiber Reinforced-Polymer (GFRP) pipes and panels by repurposing them to manufacture structural components for new bicycle and pedestrian bridges. The study covers the entire process, including conceptualization, analysis, design, and testing of a deck system, with a focus on the manufacturing process for a 7-m-long prototype bridge. The study shows promising results in the concept of a sandwich structure utilizing discarded GFRP pipes and panels, which has the flexibility to account for variabilities in dimensions of incoming products while still meeting mechanical requirements. The LCA analysis shows that the transportation of materials is the governing contributing factor. It was concluded that further development of this concept should be accompanied by a business model that considers the importance of the contributions from the whole value chain. 

In order to achieve a more resource-efficient society and a future with reduced carbon dioxide emissions, new technological challenges must be dealt. One way to reach a more sustainable world is to start re-using end-of-life structures and waste and give them a “Second Life” with new functions in the society. As fiber reinforced polymer (FRP) composites are lightweight, strong, stiff and durable materials, there is great potential to re-use decommissioned FRP structures for new resource-efficient solutions in the building and infrastructure sectors. The present paper investigates innovative solutions in re-using wind turbine blades and glass fibre reinforced polymer (GFRP) pipes as structural elements in new bicycle and pedestrian bridges. Specifically, a concept design for decking system made of GFRP pipes is developed and discussed. The main design requirements for pedestrian bridges are considered and assumptions regarding end-of-life GFRP quality and their mechanical properties have been addressed. The aim of this paper is to contribute to a sustainable use of GFRP waste and at the same time provide a more cost-effective solution for short span pedestrian bridges. In a larger perspective, the authors would like to highlight the economically profitable potential of recovering and reusing/re-manufacturing end-of-life GFRP composites. © 2022, The Author(s)

The focus of this contribution is to highlight the challenges of chemical recycling of End-of-Life glass fiber composite (GFRP) waste from wind turbine blades utilizing solvolysis/HTL (hydrothermal liquefaction) methods based on subcritical water as solvent. A multitude of investigations have been published during the years regarding solvolysis of newly produced composite laminates and known thermoset composition (epoxy, polyester, and vinyl ester). However, a real wind turbine blade is more complex and constitutes of thermosets, thermoplastics, and other materials such as balsa wood. It is a very challenging task to separate these materials from each other within the wind turbine blade structure, so the premise for recycling is a mixed waste stream where little is known about the chemical composition. In the present study, the solvolysis process for GFRPs based on sub/supercritical water at 250-370 C and 100-170 bar process conditions with catalyst (acid and base) and additives (alcohols and glycols) was studied and optimized. The samples used are representative for End-of-Life wind turbine blades. The aim is therefore to investigate if it is possible to develop a general process that can accept all material constituents in a real wind turbine blade, resulting in recycled glass fibers and a hydrocarbon fraction that can be used as a refinery feedstock.

Utmaning är här nu - vi står inför en helt ny ström av kompositavfall från uttjänta vindturbinblad. Huvudmålet för detta projekt har varit att undersöka möjligheten att utveckla en kemisk återvinningsprocess för uttjänta vindturbinblad. Dessutom har Sveriges problematik med avseende på hantering av framtida avfallströmmar från vindturbinblad undersökts.Målet har varit att utveckla en solvolysprocess som kan användas på samtliga material i ett vindturbinblad dvs härdplastglasfiberkomposit (epoxi- och polyesterhärdplast och glasfiber), termoplaster (PET, PVC, PU) och balsaträ. Efter en screening av olika alternativa solvolyssystem har en tvåstegsprocess med glykol, alkohol och vatten optimerats (T 270-330 C, P<170 bar, 16-20 timmar). Från ett epoxibaserat vindturbinblad (ca 20-30% epoxiplast och ca 60-70% glasfiber) innehållande balsaträ erhölls produktströmmarna 15 vikt% olja och 65 vikt% glasfiber samt 13 vikt% pappersmassafraktion (räknat på bladvikt). För en möjlig ekonomisk lönsam kemisk återvinningsprocess måste högvärdiga slutprodukter genereras från vindturbinbladen. Vår bedömning är att oljan är den mest värdefulla produkten trots det låga utbytet. Produktoljan som har liknade kemisksammansättning som fossil olja (väte/kol kvot, H/C 1.5) har potential att ersätta fossil olja som ingångs material i raffinaderier och bidra till att framtida s.k. plastreturraffinaderier utvecklas. På detta sätt skulle vi kunna recirkulera kolväten vilket minskar uttaget av ny fossil olja och bidrar till minskad klimatpåverkan. Rekovind har också undersökt återvinnings problematiken runt hantering av vindturbinblad historiskt och estimerat framtida materialströmmar i Sverige. Eftersom installation av vindturbiner tog fart under 1990- och 2000-talet och den beräknade livslängden var 20-25 år, är behovet av lösningar för hantering av nedmonterade blad akut. I Sverige förväntas ca 1000-blad att behöva tas ur bruk mellan 2020-2025. Historiskt har det inte varit många nedmonteringar och dessa har hanterats med olika lösningar: renovering och andrahandsmarknad, förbränning och deponi. Vanligtvis upphandlas en återvinningslösning med en entreprenör och beroende på vilket land återvinningen sker i bestämmer vilket alternativ som praktiseras. Då det inte finns något producentansvar idag är det ägaren av vindkraftverket som ansvarar för återvinningen. (Bilaga 2 rapport: Circular economy and the management of end-of-life wind turbine blades) Under projektets gång har projektidén och resultat kommunicerats och diskuterats med industrin dvs bladtillverkare, vindkraftägare samt återvinnings- och kemisk industri. Vår tolkning av dessa möten är att intresset och viljan finns hos alla aktörer i värdekedjan för att samverka mot mer cirkulära lösningar för en hållbar vindkraft. Däremot saknas den ekonomiska potential för att utveckla de avancerade kemiska processerna då de är energikrävande och de återvunna slutprodukterna är idag dyrare än nytillverkad glasfiber resp. fossil olja.

The challenge is here now - we are facing a whole new stream of composite waste from decommissioned wind turbine blades. The main objective of this project has been to study the possibility of developing a chemical recycling process for Endof- Life wind turbine blades. In addition, the challenges of future waste streams from Swedish wind turbine blades has been investigated. The goal has been to develop a solvolysis process that can be used for all materials in a wind turbine blade, i.e. thermosetting glass fiber composite (epoxy and polyester thermosets and fiberglass), thermoplastics (PET, PVC, PU) and balsa wood. After a screening of various alternative solvents systems, a two-step process with glycol, alcohol and water has been used (T 270-330 C, P <170 bar, 16-20 h) for the separation of plastics from the glass fiber. From an epoxy-based wind turbine blade (approximately 20-30% epoxy plastic and 60-70% fiberglass) containing balsa wood, the product streams obtained were: 15 mass% oil and 65 mass% fiberglass and 13 mass% pulp fraction (calculated on blade weight). For a potentially economically profitable chemical recycling process, high-quality end products must be generated from the wind turbine blades. Our assessment is that the oil is the most valuable product despite the low yield. The product oil, which has similar chemical composition as fossil oil (hydrogen/carbon ratio, H/C 1.5) has the potential to replace fossil oil as an input material in refineries and contribute to the developed of future plastic refineries. In this way, we could recycle our hydrocarbons used for plastics, reducing the use of new fossil oil and contributing to reduced climate impact. Rekovind has also investigated the recycling problem of the management of wind turbine blades historically and estimated future material streams in Sweden. Since the installation of wind turbines took off in the 1990s and 2000s and the estimated service life was 20-25 years, the need for waste management solutions is urgent for future decommissioning of these wind turbines. In Sweden, about 1000 wind turbine blades are expected to be taken out of use between 2020-2025. Historically, the decommissioned wind turbine blades have been handled with different solutions: renovation and second-hand market, incineration and landfill. Usually, a recycling solution is procured with a contractor and depending on which country the recycling takes place in decides which alternative is practiced. Since there is no producer responsibility today, the owner of the wind turbine is responsible for recycling. (Annex 2 report: Circular economy and the management of end-of-life wind turbine blades) During the course of the project, the project idea and results has been communicated and discussed with relevant industry partners, i.e. blade manufacturers, wind turbine owners and recycling companies. Our interpretation of these meetings is that there is strong interest for all members of the value chain to work together towards more circular solutions for sustainable wind power. However, there is little economic potential for the development of advanced chemical processes since the energy consumption is high and the recycling products are more expensive than virgin fiberglass and fossil oil.

Processing of polymer fibre composites has a remarkable influence on their mechanical performance. These mechanical properties are even more influenced when using recycled reinforcement. Therefore, we place particular attention on the evaluation of micromechanical models to estimate the mechanical properties and compare them against the experimental results of the manufactured composites from recycled carbon fibre material. For the manufacturing process, an epoxy matrix and carbon fibre production cut-offs as reinforcing material are incorporated using a vacuum infusion process. In addition, continuous textile reinforcement in combination with the epoxy matrix is used as reference material to evaluate the degradation of mechanical performance of the recycled composite. The experimental results show higher degradation of the composite strength compared to the stiffness properties. Observations from the modelling also show the same trend as the deviation between the theoretical and experimental results is lower for stiffness comparisons than the strength calculations. Yet still, good mechanical performance for specific applications can be expected from these materials.

A new concept, Re-Fib, was developed within an EU project, REFORM, to recycle carbon and glass fibres from polymeric composite structures, aiming to reduce energy consumption and degradation of fibre properties during recycling. The optimized thermolysis treatment, 24 h at 380 °C, was verified able to recover clean fibres from most tested composite structures containing different thermoset resins (epoxy, vinyl ester, and polyester) and various core materials such as polyvinyl chloride (PVC), polyurethane (PU), and wood. Single-fibre test was performed in dynamic mechanical analysis (DMA). The reduction of strength was found around 26% for carbon fibres and 34–40% for glass fibres. Thermally recycled glass fibres were melt-compounded with recycled polypropylene (rPP); the resultant composites showed promising mechanical properties.

In this paper the constitutive compressive behaviour of nearly parallel spread-tow textile reinforcement is studied. The striking result of our analysis is that the spread-tow type of reinforcement should obey linear relation between force and deformation. This is in contrast to standard textile reinforcements that obey a power-law type of behaviour. To support the theoretical investigation we have developed an test rig who's chief purpose is to achieve compression between nearly perfectly parallel surfaces. This is achieved using a mechanical arrangement consisting of a ball-joint.

In this paper the constitutive compressive behaviour of nearly parallel spread-tow textile reinforcement is studied. The striking result of our analysis is that the spread-tow type of reinforcement should obey linear relation between force and deformation. This is in contrast to standard textile reinforcements that obey a power-law type of behaviour. To support the theoretical investigation we have developed an test rig who's chief purpose is to achieve compression between nearly perfectly parallel surfaces. This is achieved using a mechanical arrangement consisting of a ball-joint.