Colloquiam: Revista de Materiales Compuestos

Manufacture of a train carbody section using automatic lamination processes

María Ordóñez Muñoz — Fri, 19 May 2023 13:58:03 +0200

Within the European platform Europe's Rail, whose objective is to promote research and development activities in the railway sector, can be found the PIVOT-2 project (Grant Agreement no. 881807), which addresses the implementation on track of light and environmentally friendly vehicles, reducing energy consumption and therefore the CO2 emissions derived from the transport sector.

To meet these objectives, the project seeks to achieve the weight reduction of primary structures. This way, the use of composites materials appears as an interesting alternative in a sector where their use has been very limited to non-structural components, largely due to the need to comply with fire protection regulations (EN 45545) [1]. Thanks to the development of new resins, the possibilities of these materials are increasing, being necessary to evaluate their performance in new applications.

Similarly, the characteristics of the railway industry mean that the manufacturing processes of composite materials widely used in other sectors, such as the aerospace, must be adapted. Likewise, and due to the requirements of the final product, it will be necessary to adapt the materials to these new applications, developing materials with higher grammage or ply thickness than those currently used.

The project evaluates the automatic laying of different materials developed for the railway sector. The behaviour of flat laminates is analysed, as well as the lamination of the material on core structures. Finally, studies are validated with the manufacturing of a train carbody section, using automatic lamination processes (ATL).

Welding thermoplastic composites using resistive heating: tooling design, joining procedure and demonstrator manufacturing

Aroa Iriarte Legarreta — Thu, 18 May 2023 09:12:04 +0200

Thermoplastic welding technology is a long-established technology in the industry where the efficiency of the welded joint can be approached to the properties of the base material by fast, automated and reversible joining. The joining of two thermoplastic compounds can be done by fusion bonding and reconsolidation of the pieces in the joining line. The most promising fusion bonding techniques, and nowadays with more presence in the aeronautical sector, are resistance welding, induction welding, ultrasonic welding and laser welding. Among these methods, the advantage of resistance welding is that the heat is produced exactly at the interface to be welded, avoiding unwanted heating in other parts of the piece. This method is based on the application of an electrically conductive implant between the two parts to be welded under pressure that generates heat with the passage of current. The objective of this work was to develop a resistance welding system for the joining of a thermoplastic composite assembly. A demonstrator of a representative element of the aeronautical sector was manufactured in carbon fiber and PPS composite material consisting of a skin to which two L-shaped brackets made of the same material as the skin were welded. The welding process carried out and the electrical and thermal parameters obtained show the repeatability of this process. This technology could be easily scalable for the welding of larger elements and different geometries.

Integración de estructuras en material compuesto termoplástico mediante soldadura por inducción

Javier Ávila — Fri, 11 Apr 2025 12:17:33 +0200

Los materiales compuestos termoplásticos (TPCs) están transformando la industria aeroespacial gracias a su alta tenacidad, capacidad de reprocesamiento y reciclabilidad, alineándose con los objetivos de sostenibilidad y reducción de peso estructural para minimizar las emisiones de carbono. No obstante, las técnicas de unión convencionales, como remaches y adhesivos, presentan limitaciones significativas, como la pérdida de integridad estructural debido a perforaciones, el aumento de peso y procesos largos y costosos. La soldadura de TPCs es un proceso de unión para eliminar las superficies diferenciadas de las piezas a soldar mediante una nueva consolidación del material. El entrelazamiento de las cadenas poliméricas resultante en la zona soldada posibilita la transferencia de cargas a través de la interfaz. Esta técnica permite obtener uniones ligeras, sin necesidad de elementos adicionales, y con propiedades mecánicas comparables al material base. FIDAMC trabaja sobre un método de soldadura por inducción para material compuesto termoplástico, bajo el cual han sido fabricadas probetas a partir de paneles planos. Las probetas simulan el pie de un larguerillo soldado a un revestimiento como resultado de la puesta a punto del proceso. Las probetas han sido ensayadas obteniendo propiedades mecánicas por encima del 90% respecto del valor de referencia Este trabajo ha estado apoyado por un modelo numérico creado en COMSOL Multiphysics para modelar y simular la interacción entre los campos electromagnéticos y la distribución térmica a lo largo del material durante el proceso de soldadura.

Development of smart technology for monitoring the manufacturing process of composite parts in the aerospace industry

Maialen Garaigordobil — Mon, 14 Apr 2025 15:59:24 +0200

In recent years, the aerospace industry has seen significant advancements thanks to the incorporation of composite materials, which enable the design of lighter structures with excellent mechanical properties. However, the manufacturing process of these composites remains difficult to monitor and still lacks proper standardization. This has led to the need for the development of intelligent control technologies that can be implemented to efficiently oversee the production cycle. In this work, a detailed analysis of the various stages involved in the infusion-based manufacturing process of composite parts has been carried out, identifying weaknesses and defects that may arise during production. The technology developed aims to implement a wireless monitoring system using ferromagnetic microwires embedded in structural composite components, with the goal of improving process control and reducing potential errors. Although the knowledge gained from this project is focused on a specific manufacturing process, the results obtained could be extrapolated to other sectors operating under similar conditions. In this way, the quality and added value of the parts produced with this technology are enhanced, ensuring compliance with the stringent demands of the market.

AUTOMATED MANUFACTURING OF THERMOPLASTIC COMPOSITES FOR HYDROGEN STORAGE

Prasad Shimpi — Mon, 17 Mar 2025 11:45:34 +0100

The research work is focused on developing thermoplastic composites by automated tape laying process (ATL) having acceptable gas permeability levels to store hydrogen H2 in linerless composite material tanks at cryogenic temperatures. Carbon fibre (CF) with polyamide 11 (PA11) matrix was used to manufacture composites using automated tape laying process. The manufactured composites treated in autoclave and tested for hydrogen permeability at room temperature. The results show that autoclave cured CF/PA11 composites meet the set permeability requirements for composite hydrogen storage vessel designed for pressure of 6 bar.

Desafíos y estrategias de optimización en la soldadura ultrasónica continua robótica de CFR-TP

Maryam Ahanpanjeh — Sat, 17 May 2025 00:02:13 +0200

La soldadura ultrasónica continua robótica (cUSW) es una técnica prometedora para unir termoplásticos reforzados con fibra de carbono (CFR-TP), que ofrece alta eficiencia y tiempos de procesamiento rápidos. Sin embargo, mantener la calidad de la soldadura y la robustez del proceso presenta desafíos significativos. Las características de la soldadura, como la resistencia de la unión y el rendimiento a largo plazo, se ven fuertemente influenciadas por parámetros clave durante las fases de generación de calor y consolidación. Comprender las interacciones entre el sistema robótico y el proceso de soldadura ultrasónica es esencial, ya que impactan directamente en la calidad y consistencia de la soldadura. El robot debe controlar con precisión el movimiento del sonotrodo durante la fase de generación de calor para mantener una fuerza constante, precisión de trayectoria y uniformidad de velocidad, asegurando una transferencia de energía eficiente y una fusión uniforme. Durante la consolidación, tanto la velocidad como la fuerza son cruciales, controlando la disipación de calor para reducir la temperatura de la interfaz por debajo del punto de cristalización y prevenir defectos. Para abordar estos desafíos, es esencial la monitorización en tiempo real de los parámetros clave del proceso. La integración avanzada de sensores y las estrategias de control basadas en datos permiten ajustes dinámicos para optimizar las condiciones de soldadura y prevenir defectos. Este artículo explora los desafíos asociados con la soldadura ultrasónica continua robótica de CFR-TP y analiza técnicas de monitoreo y estrategias de control para mejorar la consistencia de la soldadura y la confiabilidad del proceso.

Advanced thermal control of VARI process with self-heating mold

Manuel Laspalas — Mon, 14 Apr 2025 14:49:35 +0200

Manufacturing liquid composites with thermoset resins requires precise temperature control throughout the process. In the specific case of vacuum infusion (VARI) in a self-heating mold, one side of the part is in contact with the mold, which is the one that incorporates the heating elements (resistors), while the other side is in contact with the consumables (peelable, bleeder, mesh, vacuum bag), which imposes a substantially different thermal condition that can create thermal gradients. In order to achieve the greatest possible thermal uniformity, not only throughout the length of the part, but also throughout its thickness, additional external heating elements are usually incorporated. In the present work, the thermal control of an infusion process of a leading edge section of a horizontal stabilizer of an aircraft is developed. This control has been developed using the MPC (Model Predictive Control) method, which allows applying the necessary power to the heat sources independently to control the temperature at the measurement points, based on predictions obtained from a reduced-order thermal model (MOR). This reduced representation has been generated using the POD (Proper Orthogonal Decomposition) technique from the thermal matrices obtained from a finite element simulation (FEM) model of the prototype mold, previously adjusted and validated. In order to detect and compensate for the nonlinear behaviors present in the system, mainly due to convection, a perturbation estimator using a Kalman filter is implemented. In addition, the reduced-order model allows a thermal representation of the complete system to be obtained, which facilitates the implementation of virtual sensors in a way that controls not only the temperature at the measurement points, but also at points of the part that would not be possible to monitor with physical sensors, helping to maintain a homogeneous temperature distribution in the material during the manufacturing process. The control scheme has been experimentally validated on the prototype mold, obtaining precise monitoring of the temperature profile and complying with the manufacturing standards of the part.

Process monitoring of aeronautical-graded materials using fiber optics sensors during liquid resin infusion: study on scalability methods

Cristian Builes — Tue, 15 Apr 2025 12:13:40 +0200

The main objective of the FLASH-COMP project is to develop an advanced and efficient quality control solution, operator oriented, capable of detecting defects early and accurately during the manufacturing process. This facilitates the implementation of in-situ corrective actions, aiming to achieve a zero-defect Liquid Resin Infusion (LRI) manufacturing process while significantly, reducing waste generation in composite material production. FLASH-COMP seeks to introduce new diagnostic methods that enable real-time process monitoring, providing relevant information during the process without compromising performance or the quality of the final component. Two embedded fiber optic sensor technologies are used: Fiber Bragg Grating (FBG) and Distributed All Grating (AGF), which are combined to collect process data during the preforming and resin infusion stages. Both technologies are integrated into a complex-geometry component to monitor different critical areas simultaneously. These technologies generate valuable process data, requiring an optimal strategy of sensor positioning, that can adapt to abrupt geometric changes without compromising sensor integrity or component quality. Both sensor technologies provide relevant information related to vacuum level and leaks, temperature, resin impregnation and part curing. This type of sensor requires prior training of the operator for its correct handling and analysis of the data generated. New strategies for manipulating sensors are proposed to facilitate their manipulation on an industrial scale.

Monitoring of process parameters during the forming of SMC materials, mechanical an thermal properties (COMPCERTO Project)

Paula Rodríguez Alonso — Wed, 14 May 2025 14:37:45 +0200

In recent times, polymer matrix composite material technologies have undergone a genuine revolution, driven by the surge in demand—particularly in the transportation and energy sectors. Composites are being increasingly incorporated due to the significant weight reduction they enable in structural components, which in turn leads to a decrease in energy consumption in transportation as a result of this weight savings. Ambitious EU sustainability policies (such as the EU Green Deal or the New Industrial Strategy) are further accelerating this shift toward efficient and sustainable solutions, with a significant impact on the transportation sector, especially the automotive industry—both in conventional and emerging propulsion systems (the use of lightweight materials is expected to increase from the current 30% to 70% by 2030, with composites accounting for approximately 20%). However, the automotive sector is one of the most demanding in terms of processing times. Therefore, the optimization and monitoring of processing parameters through embedded sensors in molds is presented as a valuable tool for adapting processing times and enabling continuous quality control of parts. This paper presents the results obtained within the framework of the COMPCERTO project, which aims to develop solutions that facilitate the optimized manufacturing of components with structural requirements through Sheet Molding Compound (SMC) thermoforming processes. To achieve this, the implementation of sensors for monitoring curing, pressure, and temperature in molds is proposed, enabling the acquisition of representative values at critical points and in real time for the phenomena occurring during the thermoforming of parts in the press. Preliminary tests are carried out to optimize the curing cycle in order to determine the most suitable manufacturing parameters, and based on the results, a Design of Experiments (DoE) is proposed. Finally, mechanical, thermal, and microstructural characterizations are performed on the tests defined in the DoE. This will generate a database that serves to correlate the real-time data obtained from the parts with potential defects in the SMC components.

Hybridisation of thermoplastic composite forging and continuous fibre additive manufacturing for automotive industry

Udane Olaziregi — Thu, 10 Apr 2025 09:59:54 +0200

Thermoplastic composites are becoming increasingly important in the automotive industry due to their high strength-to-weight ratio, recyclability and cost-effectiveness. Within these composites, continuous fibre-reinforced composites offer superior mechanical properties than discontinuous fibre-reinforced composites, but their design flexibility is limited. In contrast, discontinuous fibre composites allow more complex geometries. A promising approach to overcome these limitations and improve composite components is hybrid manufacturing, which integrates multiple manufacturing techniques. In this work, we have studied the feasibility of combining the additive manufacturing of composites with continuous glass fibre (cAM) and the forging of thermoplastic materials reinforced with discontinuous fibre (GMT). A topologically optimised cAM reinforcement has been inserted into forged GMT omega profiles. The results of microscopic analysis have confirmed that there is adequate compaction between the hybridised materials. Furthermore, the results of numerical simulations replicating a three-point bending test have demonstrated the potential of cAM as a local reinforcement in forged components, as the specific stiffness of the hybrid beams was increased by up to 42%. This hybridisation technique represents a significant advancement towards the development of innovative solutions in thermoplastic composite processes, with the potential to produce lighter, stronger components adapted to complex geometries.

Comparative life cycle assesment (LCA) of a boat hatch made of glass fibre and flax fibre reinforced composites

Alberto Lopez-Arraiza — Sat, 12 Apr 2025 13:26:23 +0200

The widespread use of glass fibre-reinforced composites in the marine industry is primarily attributed to their low cost, favourable mechanical properties, and high resistance to marine corrosion. However, their limited recyclability poses significant environmental concerns at end-of-life (EoL). Consequently, more sustainable alternatives such as biocomposites reinforced with natural fibres are being explored. This study presents a comparative Life Cycle Assessment (LCA) of the fore hatch of a small boat, currently manufactured by hand lay-up using glass fibre reinforced polyester glass fibre (GFRP), and a proposed alternative with flax fabric reinforced bio-epoxy (FFRB) produced by vacuum infusion. Initially, FFRB laminates were manufactured and mechanically characterised through three-point bending tests. Based on ISO 12215-5:2019 for small craft construction, the required laminate thicknesses for the FFRB hatch were determined, achieving a 14% weight reduction compared to the GFRP counterpart. Subsequently, a cradle-to-grave LCA was performed using OpenLCA software and the Ecoinvent v3.9.1 database. Results revealed that the FFRB hatch offers lower environmental impacts in fossil fuel depletion (ΔADP = –16%) and human toxicity (ΔHTP = –54%). However, terrestrial ecotoxicity (ΔTETP = +238%) increased due to pesticide and fertiliser use in flax cultivation. In conclusion, FFRB represents an environmentally sustainable alternative for marine component manufacturing, although further research is required to enhance its end-of-life performance.

High-demand industrial applications with thermochemically recycled carbon fiber

Sonia García-Arrieta — Wed, 30 Apr 2025 10:39:35 +0200

The use of carbon fiber (CF) has increased in the last decade, shifting from the aeronautical sector to the leisure and automotive sectors. CF production requires high energy consumption and emits large amounts of CO₂. This increase in consumption generates a greater amount of CF composite waste, which must be properly managed to give it a second life. Deremco project aims to transfer and increase the TRL of different recycling technologies for composite from the wind and aeronautical sectors. The companies IDEC, BIRZIPLASTIK, and TECNALIA have focused on the recovery of post-production waste from the aeronautical sector to obtain recycled CF (rCF) through a thermochemical process. IDEC proposed the horizontal stabilizer of an aircraft's as a use case. This secondary structure requires a lower level of mechanical properties, so the introduction of rCF has proven feasible. BIRZIPLASTIK proposes developing a thermoplastic formulation with high technical requirements for automotive applications. Two formulations have been developed that meet these requirements, one of which is 100% recycled material. To carry out these success use cases, TECNALIA has worked on optimized the rCF sizing processes and integrating it into the compounding and Resin Transfer Molding (RTM) processes.

Comparison of stiffness and strength of flax, hemp and kenaf composites with other natural and synthetic fibers composites using fibre-specific parameters

Maria Asun Cantera — Wed, 21 May 2025 13:48:34 +0200

The increasing adoption of natural fibres as composite reinforcement is a promising development in materials science. These fibres have a low carbon footprint and are biodegradable, and they also have remarkable properties such as low density and high specific stiffness and strength. However, the mechanical properties of these composites are influenced by various parameters, which can complicate comparisons due to their diverse internal structures. This study focuses on two key normalised parameters: the Tsai modulus, which represents the trace of the stiffness matrix tensor; and the area of the Omni failure envelope in stress space. Our analysis of published data on unidirectional flax, hemp, jute, and kenaf composites shows that trace-normalised longitudinal Young's modulus can effectively facilitate stiffness comparisons between natural and synthetic fibre composites. A new and innovative way of measuring strength is suggested. This is based on the radius of a circle that matches the area of the Omni stress envelopes. This method is both robust and reliable for quantifying and comparing material strength. Although, extensive mechanical data on natural composites is available, it is difficult to establish design criteria for comparing them. Addressing this gap presents a significant opportunity to unlock the full potential of natural fibres in composite applications, paving the way for a more sustainable future in engineering materials.

Composite sustainability for aviation - Problem or solution?

Tamara Blanco Varela — Wed, 23 Apr 2025 14:21:14 +0200

Composite materials have highly contributed to the reduction of CO2 emissions of last generation aircrafts, due to their lightweight capabilities. However, the environmental burden during composite raw material production, part manufacturing and waste treatment versus aluminium alloys has become a priority during recent years and needs to be addressed asap. This applies to current aircraft but above all to ensure that composites are the best material choice for future more conventional or breakthrough products based on sustainable aviation fuel or liquid hydrogen propulsion.This presentation has the intention to be a general and comprehensive overview of the current situation and opportunities regarding composite sustainability for commercial aeronautical sector, including:

Problem understanding: composites are key for more sustainable aviation.
As-is situation: raw material and part production, composite scrap treatment.
Opportunities to develop more sustainable composites: biosourced composites and mass balance, substance compliance, industrial carbon footprint reduction, recycling technologies and recyclable resins.
Some tips and recommendations about how to approach the development of more sustainable composites and what to prioritize from a technical point of view.

Desarrollo de la tecnología de calandrado para la reutilización de residuos de pre-preg multiaxiales no curados procedentes del sector aeronáutico

María Ariño — Fri, 16 May 2025 17:19:14 +0200

Esta investigación se centra en aprovechar los residuos de pregreg multicapa sin curar generados durante la producción de componentes aeronáuticos, con especial énfasis en los procesos de AFP (Automatic Fibre Placement) y ATL (Automatic Tape Laying). Estos residuos, que presentan características repetitivas en cuanto a tamaño, forma y apilado, se procesan mediante un sistema mecánico de calandrado para darle una segunda vida al material. Este método desarrollado por FIDAMC está basado en preparar los residuos de ATL de prepreg sin curar en tiras longitudinales orientadas en la dirección predominante. Posteriormente, estas tiras se procesan mediante calandrado en condiciones específicas de temperatura, velocidad y ratios de reducción de espesor en diferentes pasos. Como resultado, se obtiene un material reusado intermedio manipulable para la fabricación de nuevas piezas. Este material se ha caracterizado física-química y mecánicamente para optimizar sus propiedades mecánicas y asegurar su viabilidad como material reusado. Aunque las piezas aeroespaciales de material compuesto deben cumplir estrictos requisitos de seguridad, existen aplicaciones no críticas donde se pueden emplear materiales más ecológicos y económicos, como la fibra de carbono reusada. Esto permite una reducción significativa del impacto ambiental y de los costes asociados. Para estudiar la viabilidad de fabricación con este material, se ha fabricado un demostrador de costilla de borde de ataque del elevador (elevator) del estabilizador horizontal (HTP) mediante el proceso de termoconformado. Este estudio pretende demostrar el desarrollo y aplicación de nuevos materiales reusados, los cuales pueden ser utilizados en piezas semi-estructurales en el sector aeronáutico, o bien, en el sector transporte, en general. Se ha estudiado el material mediante una caracterización físico-química (micrografía, DSC, digestión y porosidad) y mecánica (tracción, compresión, ILSS, G1C, IPSS, CAI, OHC y FHC), así como otros métodos de caracterización avanzada. También se ha estudio su viabilidad de fabricación mediante la producción de un componente de geometría compleja. Además, se han propuesto diferentes alternativas para mejorar la calidad el material y ampliar el abanico de aplicación. Los resultados obtenidos confirmaron el potencial del material reusado para aplicaciones no críticas, demostrando que cumple con los requisitos funcionales de este tipo de componentes y recorriendo el camino hacia una mayor sostenibilidad en el sector.

Design of a small sustainable wind blade

Rafael Carnicero — Wed, 26 Mar 2025 14:14:33 +0100

The European Union is committed to becoming the first carbon-neutral continent by 2050. To this end, member countries have outlined a long-term strategy to achieve this goal. Among the cross-cutting elements that will make this possible is the Circular Economy. In this context, the aim is to reduce raw materials by extending the useful life of products, reusing them, recycling materials, etc. In the wind energy sector, between 80 and 90% of wind turbines are currently recycled. Wind turbine blades, manufactured mainly from composites, are difficult to recycle in terms of economic efficiency. Even so, several technical solutions currently exist at varying levels of technological maturity.

The work presented is the design of a sustainable wind turbine blade, replacing the epoxy-type thermosetting resins used until now with a thermoplastic resin with similar mechanical properties, with the advantage that the composites produced are easily recyclable. This new liquid thermoplastic resin, AKELITE, patented by the CSIC group, is capable of producing sustainable and 100% circular composite materials.

A 3D CAD model was created from a series of cross-sections of the blade. This model describes the blade's aerodynamic surface, so that in the finite element design phase (ANSYS Workbench), the laminate is defined from the outside in. The laminate design prioritizes longitudinal stiffness, ensuring the presence of layers in all traditional layers (0°, 90°, and ±45°), maintaining symmetry, and progressively reducing thickness from root to tip. The blade was subsequently manufactured and finally tested. The blade is currently being recycled for subsequent life cycle analysis.

This work is part of a project under the call for "Projects aimed at the ecological transition and the digital transition" with the participation of three research groups: CIEMAT, the University of Girona, and the CSIC.

Eco-design in Automotive through 'Material Matrix Assessment': Use Case in the Salient Project

Vanessa Ventosinos — Fri, 11 Apr 2025 13:32:22 +0200

Eco-design in the automotive sector integrates environmental considerations into the product development process to minimize impact throughout the vehicle’s entire life cycle. This approach addresses aspects such as resource efficiency, emission reduction, and end-of-life options (recycling, reuse, etc.). In recent years, eco-design has gained relevance due to increasing regulations and growing user awareness of sustainability. However, its implementation is often based on Life Cycle Assessment (LCA), a complex and demanding method during early design phases, as it requires detailed data to deliver reliable comparative results. This can delay the development time of new components—a critical parameter in the automotive industry. To overcome this limitation, CTAG has developed its own methodology, the Material Matrix Assessment, which enables rapid preliminary analysis of multiple designs without requiring detailed specifications. This qualitative methodology can identify designs with the highest environmental potential using key metrics selected by a multidisciplinary team. Each category is scored and weighted according to its relevance, resulting in an overall score for each design concept. The Material Matrix Assessment was successfully applied in the European SALIENT project, using a front-end structure as a use case. In addition to facilitating the selection of the design with the lowest environmental footprint from the earliest stages of development, the methodology also enabled a system weight reduction of over 40%.

Environmental sustainability assessment of a recyclable wind turbine blade: Preliminary results

Ana Rosa Gamarra — Mon, 14 Apr 2025 17:39:30 +0200

Recycling wind turbine blades is a key element in ensuring the sustainability of the energy transition. Conventional wind turbine blades made of epoxy-based composite plastics cannot be recycled and are mostly disposed of in landfills. This paper presents the environmental sustainability assessment of a blade manufactured with a new recyclable liquid thermoplastic resin. A Life Cycle Assessment (LCA) methodology was applied to calculate the environmental footprint, including 16 impact categories, enabling a comparison between the environmental impact of a conventional blade and one based on the new recyclable resin. The results from the resin production stage showed that the innovative resin had a higher environmental impact than epoxy. For example, in the climate change category, the emissions were 7.89 kg CO₂ eq./kg compared to 3.99 kg CO₂ eq./kg. However, it is necessary to evaluate the full life cycle of the blade, including use phase, recycling process, resin recovery, and the manufacturing of new blades. The results of the full life cycle assessment of a blade manufactured with the recovered innovative material will be presented. The life cycle approach is essential for assessing novel material applications to support the sustainable deployment of renewable energy technologies, including circularity criteria.

Impact-Fatigue of Self-Reinforced Polyethylene Terephthalate

Jon Aurrekoetxea — Fri, 11 Apr 2025 15:22:23 +0200

The objective of this work was to characterise the impact-fatigue behaviour of self-reinforced polyethylene terephthalate (srPET). The impact characterisation results, covering the range of incident energies from subcritical to perforation, show that the main deformation mechanism is plastic deformation followed by tensile fracture of the PET fibres, and that the energy penetration threshold for a 1.1 mm thick specimen is 13.9 J. In single-impact scenarios, srPET has a specific penetration threshold of 3.24 J/g, which is worse than self-reinforced polypropylene (srPP). However, if the environmental goal is to reduce waste volume, srPET is a better option since PET has a recycling fraction of 18.2%, compared to 2.7% for PP. Additionally, srPET guarantees a lifespan of 100 impacts for incident energies up to 60% of its penetration threshold, while srPP cannot exceed 40%. Finally, the fatigue life loss of srPET is also more gradual, a key aspect from the structural integrity point of view.

Increasing Profitability in Wind Turbine Blade Recycling: A Pyrolysis-Based Approach with Thermal Treatment of Volatiles

Alexander Lopez-Urionabarrenechea — Tue, 15 Apr 2025 20:07:13 +0200

Pyrolysis is a technically suitable process for recovering fibres from reinforced plastic waste that may also contain other types of materials (wood, foam, lacquer, etc.), such as wind turbine blades at the end of their useful life. The economic profitability of the pyrolysis recycling process depends mainly on the value of the recovered fibres, since pyrolysis liquids currently have no industrial application (and are therefore hazardous waste) and the gases are usually used to partially supply the energy requirements of the process, which is endothermic. Given that the wind turbine blades currently being retired are mainly made of glass fibres, which have low economic value, the profitability of the pyrolysis recycling process for this type of blade is a critical issue. This paper presents an analysis of the increase in the profitability of a wind turbine blade pyrolysis process that includes a treatment stage to improve the properties of the liquid and gaseous products. To this end, the investment required for this treatment (additional process units) has been defined and the energy costs and liquid waste management costs have been quantified in scenarios with and without treatment, including in the latter case the income from the sale of hydrogen. With this information and the amortisation expense, the incremental income statements derived from carrying out the treatment have been prepared, obtaining the net cash flows (NCF). The NCF has been used to calculate the net present value (NPV) of the investment project, as this is the best criterion from a financial point of view for evaluating a project. Finally, a sensitivity analysis was performed taking into account deviations in the investment to be made, income and costs. The results show that the cost of managing liquid waste is the parameter with the greatest influence on profitability, meaning that implementing the treatment increases the profitability of the recycling process.