Scipedia: Documents published in 2026

Reutilization of CFRP elements from aircraft dismantling for the reinforcement of reinforced concrete structures

Norbert Blanco — Tue, 22 Apr 2025 12:46:23 +0200

In the coming years, the growth of aircraft fleets is expected due to increased globalization and transportation needs, leading to a rise in the use of CFRP (Carbon Fiber Reinforced Polymer) composites thanks to their excellent specific properties. This implies that the sector must face the challenge of dealing with CFRP elements from aircraft that have reached the end of their useful life, without a clear and sustainable alternative to landfill disposal currently available. On the other hand, the rehabilitation of buildings and civil infrastructure is essential to prolong their useful life and reduce energy consumption and environmental impact associated with construction. Currently, there are various techniques for using CFRP composites to reinforce reinforced concrete structures, improving their flexural response. However, the manufacturing cost of these reinforcement materials and the associated environmental cost limit their wider use. Therefore, the reuse of CFRP composites from other sectors can represent a very interesting alternative. This work explores the possibility of using CFRP elements from the aerospace sector to reinforce reinforced concrete structures. Specifically, the capacity of these reused CFRP composites to be used as external reinforcement in concrete beams subjected to bending is analyzed. The results are compared with those of a reference beam reinforced with newly manufactured CFRP composite material. It is concluded that it is feasible to reuse CFRP materials from the aerospace sector for the reinforcement of reinforced concrete beams.

Nanocomposites based on PVDF-HFP and piezoelectric nanoparticles fabricated by solvent-casting and electrospinning techniques for sensing applications

Esther Arribas Yuste — Mon, 14 Apr 2025 23:24:13 +0200

This work deals with the development of flexible piezoelectric nanocomposites based on PVDF-HFP copolymer reinforced with ZnO nanoparticles (NPs) for biomedical sensing applications. Two fabrication techniques are analyzed: solvent casting and electrospinning. The films obtained by the solvent casting technique, characterized by FTIR-ATR and Atomic Force Microscopy (AFM) in PFM mode, show a significant increase of the piezoelectric coefficient (d₃₃) for ZnO NPs concentrations equal or higher than 12% by weight, with respect to the unreinforced polymeric matrix. FTIR analysis estimated an electroactive phase content close to 60% in the reinforced samples. On the other hand, the preliminary study of optimization of electrospinning parameters, evaluated by Scanning Electron Microscopy (SEM), demonstrates the feasibility of forming mats with high fiber content and homogeneous nanofiber diameters between 110-140 nm, whose morphology depends on parameters such as the speed of the collector. These preliminary results are promising for obtaining flexible piezoelectric fabrics by both fabrication routes.

Characterization of 3D-printed cordierite-rGO nanocomposites for aerospace applications

Maria Garcia-Martinez — Mon, 14 Apr 2025 23:00:45 +0200

One of the most critical challenges in the aerospace industry is the mismatch in the coefficient of thermal expansion (CTE) between optical components in satellites and their metallic supports, which limits system reliability and performance. Ceramic materials, due to their superior thermal properties, offer a potential solution; however, their adoption has been limited by the complexity of their geometries and conventional manufacturing constraints. Additive manufacturing has opened new opportunities for the development of advanced ceramics, including ceramic matrix composites (CMCs). Within the framework of the AERORECORD-3D project, funded by the Spanish Ministry of Science and Innovation, ceramic cordierite-based supports reinforced with reduced graphene oxide (rGO) have been developed for aerospace applications. In this study, cordierite nanocomposites with varying rGO contents were successfully fabricated via 3D printing. Their thermal, electrical, and mechanical properties were evaluated to assess their performance, exploring their potential as advanced materials for demanding space applications. This work represents a significant step toward the implementation of 3D-printed ceramic nanocomposites by combining innovative materials with advanced additive manufacturing technologies.

Caracterización de las propiedades mecánicas de estructuras kirigami impresas en 3D y sus conexiones fabricadas con materiales compuestos

Montserrat Dolz — Mon, 14 Apr 2025 22:00:24 +0200

El avance de la tecnología de impresión 3D ha permitido la creación de estructuras complejas con formas únicas, como los diseños basados en kirigami, inspirados en el arte de cortar papel para formar estructuras tridimensionales. Estas estructuras ofrecen beneficios significativos, como una construcción ligera, despliegue rápido y la capacidad de soportar cargas mecánicas y absorber energía de deformación. Sin embargo, existe una investigación limitada sobre el comportamiento de estas estructuras y sus conexiones críticas cuando se fabrican con materiales compuestos mediante técnicas de impresión 3D.

Este estudio examina las propiedades mecánicas de estructuras kirigami impresas en 3D y sus conexiones, centrándose en mejorar el comportamiento de unión y optimizar el uso del material. Se emplea el marco Space Mapping para abordar la anisotropía inherente de los compuestos impresos en 3D, transformando el comportamiento direccional complejo del material en un dominio isotrópico equivalente. Este enfoque permite aplicar modelos no lineales isotrópicos ya consolidados, mejorando la precisión de la simulación y reduciendo el coste computacional.

Se utilizan simulaciones por elementos finitos para modelar el comportamiento de las estructuras kirigami, prestando especial atención a las propiedades del material, la adhesión entre capas, la dirección de impresión y la orientación de las fibras en el material compuesto. Se llevan a cabo ensayos mecánicos para validar las simulaciones, centrándose en la rigidez y resistencia de los pliegues y uniones bajo diferentes condiciones de carga. Mediante la mejora de los mecanismos de plegado y la optimización de la distribución del material en las zonas críticas, esta investigación busca demostrar cómo se comparan las estructuras kirigami frente a los diseños sólidos tradicionales en aplicaciones que requieren tanto resistencia como adaptabilidad.

Estos resultados son especialmente relevantes para sectores donde se necesitan diseños ligeros y flexibles, como la aeronáutica, la automoción, el transporte marítimo y la ingeniería civil. Combinando análisis numérico con validación experimental, el estudio ofrece aportaciones valiosas para la optimización de los puntos de plegado y conexión en estructuras kirigami impresas en 3D, con vistas a su aplicación en la ingeniería avanzada.

Towards materiality: A novel energy assessment approach for CFRP manufacturing

Jannis Eckhoff — Mon, 14 Apr 2025 21:57:23 +0200

Energy efficiency and the associated quantification of performance data present companies with major challenges for the brownfield. ISO 50001 plays a major role, particularly against the backdrop of increasing regulatory requirements at national and international level. Due to rising taxation and energy prices, the economic aspect of eco-efficient production is also becoming increasingly important. To be able to indicate the current status of production in key performance indicators (EnPIs), it is necessary to precisely quantify energy in the context of production. This work shows an approach for the integration of combined measurement approaches for electrical power in existing industrial systems. In addition to mobile solutions, static sensors with an Open Platform Communications Unified Architecture (OPCUA) and Internet of Things (IoT) interfaces are used for seamless data integration and processing. A core aspect of the work is the development and description of a materiality matrix to determine the systems that need to be considered for optimization and simulation. This paper demonstrates the applicability of the approach and describes the implementation of power measurement. The results show that this approach is an effective method for ISO 50001 compliant measurement. This serves as a basis for optimization in the brownfield and simulation for the greenfield.

Experimental characterisation of the translaminar fracture toughness of an additive manufacturing c-CFRP composite

Alex Fernández — Mon, 14 Apr 2025 13:32:24 +0200

Fibre breakeage in composite materials is usually a determining damage mechanism for its structural integrity due to the high energy associated, in comparison with matrix cracking. For this reason, the assessment of the translaminar fracture toughness is relevant for accurate numerical predictions of composite structures. However, there are scarce investigations related to this topic for additive manufactured composites reinforced with continuous fibres. In this investigation, the translaminar fracture toughness of 3D-printed continuous fibre reinforced polymer (c-CFRP) composites was characterised using double-tapered compact tension (2TCT) specimens. The 2TCT geometric dimensions were obtained through a parametric study to prevent undesired failure modes. The results show a translaminar fracture toughness of 17.4 N/mm for the tested 0/90 laminates. The fracture toughness corresponding to the tensile failure of the 0° ply was derived using a rule-of-mixtures approach. Post-mortem micrographic and X-ray analysis indicated the presence of fibre pull-outs in the crack surface and confirmed the absence of any additional damage, validating the use of 2TCT geometry for the determination of the translaminar fracture toughness in additively manufactured c-CFRP composites.

Production by pultrusion and mechanical characterization of fibre reinforced thermoplastic composites

Ana Rita Carreiras — Mon, 14 Apr 2025 11:37:02 +0200

Thermosetting matrix composites are by far the most use composite solutions in the market. Thermosetting matrices are not currently possible to recycle by convenient means, which makes them a poor sustainable solution. In environmental terms, these matrices materials are also more harmful due to gas emissions during the curing process that can be considered harmful to the workers. Thermoset composites also have some disadvantages from the point of view of mechanical behaviour, being less ductile and resistant when compared to thermoplastic matrix composites. Despite the very high viscosity of thermoplastic materials that is a main problem regarding composite processing, they have advantages such as being recyclable, cleaner workspaces and greater availability, as well as a longer shelf life. This paper aims to be a contribution to increase use of thermoplastic matrix composites as alternative to the more traditional thermosetting based composites. First, thermoplastic matrix prepregs were produced in tape form by dipping the fibres into a molten polymer bath. Carbon and glass fibres are used as reinforcement material, testing their combination with thermoplastic polymers and recycled polymers. The use of prepregs is more attractive on the market as the process of mixing and selecting the raw materials is carried out prior to their application in a consolidation process. The prepregs were then processed by pultrusion, which is characterised by its continuous nature, allowing the manufacturing of constant cross section profiles for structural applications. The pultrusion of thermoplastic composites is still a novelty and therefore presents challenges. The determination of the best combination of operational parameters was also conducted in this study. Finally, the produced profiles were subjected to mechanical tests as a way of assessing the quality of the processed composites. The mechanical properties obtained will be compared to those predicted by the application of micromechanical models using experimentally obtained mass fibre fraction content.

Development and integration of printed strain gauge-based sensors for structural health monitoring in composite material repairs of wind turbine blades

EDURNE TELLECHEA — Mon, 14 Apr 2025 11:00:23 +0200

Structural health monitoring is essential to ensure safety and extend the service life of critical components in renewable energy systems, such as repaired wind turbine blades. This study presents the development of strain gauges printed using advanced functional printing techniques, optimized for integration into composite materials and tailored to the mechanical characteristics of repaired areas to assess the effectiveness and durability of structural repairs. The integration of these sensors would enable real-time monitoring of key parameters, such as microstrains, during the operation of the blade after repair. The experimental work included the printing of strain gauges, evaluation of different substrates, and cyclic loading tests under controlled conditions to assess the accuracy and sensitivity of the printed gauges. Additionally, composite material coupons were characterized under tensile and compressive loads to analyse the impact of gauge integration on the mechanical properties of the composite. Preliminary results demonstrate the feasibility of this approach, although full validation is required, including aging studies, testing in real operational environments, and exposure to extreme temperature variations prior to industrial implementation.

Lightweight conductive paths for structural health monitoring systems using 3D-printed metallic and carbon-filler based inks

Tasdeeq Sofi — Mon, 14 Apr 2025 10:19:23 +0200

Guided wave-based structural health monitoring (SHM) systems using piezoelectric sensors for composite parts face challenges due to the weight of copper wiring. This study developed lightweight, 3D-printed conductive paths using silver ink (Dycotec Materials) and epoxy (Epolam 8052) doped with carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). The inks were characterized for their weight and conductivity with a Keithley 2410. Following which they were evaluated for signal transmission of guided waves and easy integration with induction heating. Nanoparticle-doped epoxy inks demonstrated increased viscosity and controlled circuit dimensions, though dispersion issues led to voids and agglomerates. Unmodified silver inks did not show good printing quality; however, the quality was improved significantly with the adding of GNPs. Circuits from both inks were evaluated for conductivity and signal transmission. Silver inks achieved conductivity levels comparable to copper and effective signal transmission, while nanoparticle-doped epoxy had significantly lower conductivity and signal loss (2-3 times), even at its best formulation. A lightweight film integrating silver circuits was successfully bonded to a composite panel using induction heating, demonstrating a rapid integration method for SHM systems. These findings highlight the potential of metallic and nanoparticle-doped inks to replace traditional copper wiring, offering significant weight reduction, and easier integration capabilities for SHM applications.

Mechanical behavior analysis at low temperature of flax/epoxy laminates

Gabriel Enrique Sánchez Escudero — Sun, 13 Apr 2025 11:49:34 +0200

The growing environmental consciousness of recent years has driven the composite materials industry to increasingly adopt natural fibers as a sustainable alternative to synthetic ones, aiming to reduce the ecological footprint of manufacturing processes. Replacing conventional synthetic fibers with natural counterparts, such as flax, offers a significant decrease in energy consumption during laminate production, enhancing overall process sustainability. This study explores the mechanical performance of a flax fiber-reinforced epoxy laminate with a twill weave configuration. The material was tested under tensile and in-plane shear loading at both room temperature and subzero conditions (–40 °C and –70 °C). The laminate demonstrated a nonlinear stress–strain response, characterized by three distinct regions, suggesting that a trilinear model may be appropriate for its numerical simulation. The influence of temperature on the mechanical behavior was assessed in both the longitudinal and transverse tensile directions, as well as in shear. Results reveal that lower temperatures lead to increased stiffness and strength, although differences between –40 °C and –70 °C were not substantial.

Multilayer Composite Prepreg Reuse of Composite Parts

Pablo Vazquez — Sat, 12 Apr 2025 18:34:33 +0200

If we want to maintain, or even increase, the current level of use of high-performance composite materials, some major challenges need to be solved: reduction in the cost of the final structure, reduction in energy consumption during the manufacturing cycle from the base material to the final structure, and develop strategies following the “5Rs Circular Economy” approach: Rethink, Refuse, Reduce, Reuse and Recycle technologies to produce materials and structures with high added value. This communication has the intention to show Airbus work on the reuse of multilayer uncured prepreg scrap generated in AFP, to be used for the manufacturing of non-loaded parts by BMC (Bulk Moulding Compound). We will deal with the problem understanding; multilayer prepreg scrap represents an important part of the fresh scrap generated in the manufacturing plants and no feasible technology has been yet developed to treat this type of residue due to the difficulty of separating layers without completely damaging the composite prepreg. We will also detail the multilayer prepreg scrap treatment, part production, material characterization, and the opportunities to introduce parts made of reuse prepreg on real aircraft.

Analysis of Delamination Behavior in Mode I under Thermal Environment Exposure in Adhesive Joints of Carbon-Epoxy Composite Materials

Paula Vigón — Fri, 11 Apr 2025 19:25:45 +0200

This study analyzes the delamination behavior in mode I, under static and fatigue loading, in adhesive joints on a composite material with an epoxy matrix and unidirectional carbon fiber reinforcement (CFRP). The samples were exposed in a climate chamber at 60°C and 70% relative humidity for different periods (no exposure, 1, 2, and 4 weeks). Subsequently, standardized DCB tests were performed to evaluate the effect of environmental aging on interlaminar fracture toughness and adhesive strength. After an initial static characterization, reference parameters for fatigue tests were defined, obtaining initiation (ΔG–N) and crack growth (G–da/dN) curves. The initiation data were analyzed using a Weibull probabilistic model. The results show a change in the epoxy adhesive behavior with exposure time, evidenced by a reduction in the fatigue limit and an increase in crack propagation rates.

Experimental Evaluation of the Damping Factor in Laminated Composite Materials

Daniel Trias — Fri, 11 Apr 2025 18:56:56 +0200

The use of natural fibers in composite materials is gaining significant interest in the current context of emission reduction. In this regard, along with the fact that it is an eco-responsible material, it becomes a very attractive option, although its clear inferiority in mechanical properties such as stiffness and strength compared to glass fiber, and certainly carbon fiber, raises doubts about its use in structural applications. However, flax fiber's ability to absorb and damp vibrations is much greater than that of the aforementioned high-performance structural fibers. The experimental determination of the damping coefficient emerges as a key aspect that may allow for the consideration of natural fibers in structural applications requiring damping. Existing standards are very generic and do not account for some important details in the execution of the test. The present work presents the experimental method used for determining the damping coefficient of laminated composite materials using accelerometers and a vibration exciter (shaker), including consideration of the analysis of the effect of certain parameters such as the positioning of accelerometers, excitation methods, and data reduction methods.

Manufacturing of new composites with a polypropylene matrix and latxa sheep wool reinforcement

Ander Larruscain — Fri, 11 Apr 2025 18:29:23 +0200

The development of new sustainable materials is key to meeting growing demand without compromising the planet’s future. To achieve this, it is essential to reduce environmental impact through strategies like those of the circular economy. One example is the use of Latxa sheep wool, a breed associated with Idiazabal cheese in the Basque Country. This wool has interesting physical, chemical, and mechanical properties, but currently lacks industrial applications. Therefore, it could be used as reinforcement in composite manufacturing, also supporting the local economy. In this study, polypropylene (PP) was used as the matrix—one of the most widely used thermoplastic polymers due to its versatility, good barrier properties, and chemical resistance. However, PP has few functional groups, which limits interaction with other materials. This may lead to poor adhesion at the fiber-matrix interface, affecting the cohesion and properties of the composite. To address this, composites of PP with Latxa wool fiber (PPWF) were prepared, analyzing the effect of modifying the PP with maleic anhydride (MAPP) to enhance compatibility between the matrix and the protein-based fiber. MAPP was added in a proportion of 10% relative to the wool fiber. The results show that adding 20% wool to the modified matrix significantly improves both the strength and modulus of the PP.

Effect of Environmental Degradation on the Fatigue Resistance of Mode II Adhesive Joints in Carbon/Epoxy Composite Materials

Paula Vigón — Fri, 11 Apr 2025 17:06:23 +0200

This study analyzes delamination in CFRP adhesive joints under mode II loading in both static and dynamic regimes. The ENF test was used to evaluate the effect of exposure to salt spray and a climatic chamber over various periods—one, two, four, and twelve weeks—as well as for unaged specimens. Based on the experimental data, fatigue initiation curves (ΔG-N) and fatigue crack growth curves (G-da/dN) were constructed to analyze both degradation processes. In the fatigue initiation phase, the data were analyzed using a probabilistic model based on a Weibull distribution. The most relevant findings of this study are as follows: regarding the fatigue limits obtained for the adhesive joint under mode II fracture, a decrease in load-bearing capacity was observed due to degradation processes—around 20% under static loading conditions for salt spray exposure, and 25% for hygrothermal degradation. As for the fatigue crack growth phase, the crack propagation rates were found to depend on the specific environmental degradation process to which the tested specimens were subjected.

Optimization of a car hood using natural fiber composite and 3D-printed PLA foam

Aritz Esnaola — Fri, 11 Apr 2025 15:23:13 +0200

Thanks to the wide range of available cores and skins, the design and manufacture of sandwich structures allows for many variations, but conventional manufacturing processes limit design freedom when it comes to geometries. In recent years, interest in sustainable materials, such as plant-based resins and natural fibres, has grown. Furthermore, recent advances in 3D printing have opened up new design possibilities, including the use of biodegradable foams and functionally graded structures. This study presents the development of a 1:6 scale car bonnet, where the skin is made of bio-epoxy resin reinforced with flax fibre and the core is a PLA foam produced via additive manufacturing. Two variants were considered: in the first, the core was distributed homogeneously across the entire bonnet surface, and in the second, it was distributed in areas selected through topological optimisation simulations. As both bonnets have the same mass, the density of the homogeneous bonnet had to be lower. This was achieved by programming different 3D printing parameters. Quasi-static load test results show that the bonnet with the optimised distribution is 25% stiffer. The study's main conclusion is that manufacturing cores using 3D-printed foamed PLA enables a wide range of densities and design possibilities that are not feasible with conventional materials and manufacturing processes.

Ballast Impact Damage Characterization. Determination of Acceptance/Rejection Criteria for Railway Components Made of CFRP.

Francisco José García Piñeiro — Fri, 11 Apr 2025 08:27:24 +0200

In recent years, the railway sector has been developing high-responsibility lighter components (such as the running gear frame), made from composites (mainly CFRP) to meet the new challenges of the sector. However, these components may be more sensitive to damage from impacts compared to conventional metallic ones. In high-speed train operations, elements located on the lower parts of the train are exposed to impacts with ballast stones that are lifted as the train passes (v > 200 km/h), leading to damage (sometimes internal and not visible) that can limit the use of these materials. During the development of CFRP components by Talgo, the damage caused by these types of low-velocity impacts has been analyzed and evaluated. These impacts can cause damage that requires more or less complex technologies (such as ultrasound) for evaluation, which are difficult to implement in maintenance operations. From the studies conducted on CFRP materials (compliant with the EN-45545 standard for fire, smoke, and toxicity), it has been found that acceptable approaches can be used, with easily implementable measures in routine inspections, to estimate the damage caused by ballast stone impacts. In these analyses, it was observed that: a) It is possible to estimate the impact energy level through the depth of the surface damage, b) it is possible to estimate the size of the internal damaged area based on the energy level, and c) it is possible to determine the residual strength based on the size of the internal damaged area. These results allow us to establish both acceptance requirements and criteria for the repair and rejection of materials

Part 2: Recyclability and revalorization of railway components made of composite materials

Marta Cerdeira Peinado — Thu, 10 Apr 2025 12:46:34 +0200

This PART 2 is the continuation of the project: “PART 1: recyclability and revalorisation of railway components made of composite materials”. Following the successful development of the recycling process for the Lightweight Running Gear Frame prototype and the formulation of a 3R epoxy resin suitable for use in the railway sector, the project advances with the following challenges:

Revalorisation of Recycled Carbon Fibre (rCF) into new fabrics, by obtaining hybrid rCF and polyamide 6 (PA 6) yarns by adapting and optimising textile processes to incorporate recycled fibres into new intermediate products.
Production of a new prepreg and its laminates. The new prepreg and its laminates will be produced using the dry fabric obtained in the previous objective and the 3R epoxy resin, developed in PART 1 of the project.

The overall conclusions of the project are that: the recycling process is suitable for post-consumer components, the spinning and weaving methods are effective for dealing with this type of fibres and the 3R laminates manufactured are of high quality and ready to be evaluated in terms of their properties.

Functionally Graded Foamed PLA Cores for Optimized Vibratory Behavior in Sandwich Panels

Jon Rodriguez — Thu, 10 Apr 2025 11:40:34 +0200

Fused filament fabrication of foamed PLA enables lightweight structural parts with adjustable density and stiffness. This material expands during printing, making it ideal for functionally graded materials. It can serve as a sandwich core, enhancing lightweight properties. These panels can be a promising type of panel, as their behavior, such as vibracoustic, can be customized. However, their effectiveness in vibration attenuation remains unexplored. This study designs, manufactures, and tests 3D-printed foamed PLA sandwich panels with variable stiffness and density to improve vibroacoustic performance. The material’s Poisson’s ratio and elasticity modulus were characterized as a function of density, controlled by hot-end temperature and extrusion flow rate. A finite element model with spatially variable mechanical properties was developed for optimization. A genetic algorithm determined the optimal core properties to maximize the first two natural frequencies of a plate with one fixed edge and three free edges. The best designs were fabricated and tested, showing significant increment in the first two natural frequencies. This work advances the design and manufacturing of 3D-printed foamed PLA sandwich panels and contributes to high-performance, functionally graded components for enhanced vibroacoustic behavior.

Robotic solution for the dismantling of aeronautical composites

Alejandro Marques — Thu, 10 Apr 2025 09:48:34 +0200

The implementation of composite materials within the industry is a trend that has been developing for many years. In the case of the aeronautical industry, the gradual replacement of metallic parts by composite elements is increasing with each new aircraft model developed. However, these composites imply a challenge towards their end of life, since their dismantling and processing is under development, and they are currently processed as waste, with no recycling or reuse opportunities. In this context, a robotic dismantling solution is proposed by means of abrasive water jet cut, guided by a digital twin system. This system allows operator-guided cutting of the composite part, permitting the selection of the specific area to be dismantled on the aircraft itself. Thanks to a portable abrasive water jet system, operated by a collaborative robot, the cutting operations can be carried out in situ. This dismantling system is placed on a portable platform, operated by an AGV (Automatic Guided Vehicle) system integrated in the dismantling system itself, capable of transporting it along the working area. In this way, new strategies for dismantling and reusing the composite material at its end of life are proposed. These new options include the extraction of complete parts selected by the operator for their reuse, the elimination and/or recovery of rivets and the adaptation of the parts to be dismantled for a subsequent recycling process.

Thermal and flame retardant properties of recyclable disulfide based epoxy vitrimers

Alaitz Rekondo — Thu, 10 Apr 2025 09:20:33 +0200

The development of flame-retardant epoxy vitrimers which are suitable for use as a composite matrix material is essential for the transition to a sustainable circular economy. In this work the thermal and flame-retardant properties as well as the rheological characteristics of epoxy vitrimers based on 4-Aminophenyldisulfide (4-AFD) hardener and with different reactive and additive Phosphorus based flame retardants (FR) with different oxidation states were studied. The use of 4-AFD as curing agent imparts vitrimeric properties to the material and allows repairing, reprocessing and recycling. A series of epoxy vitrimers (EV) were prepared aiming to improve the flame-retardant properties while maintaining dynamism and reprocessability. The neat EV (T_g ∼125 °C) showed a limited oxygen index (LOI) of 20.9 ± 0.4 %O₂ and no classification and heavy dripping in the UL-94 vertical burning test. With 1.5 wt% of Phosphorous (P) in the EV, LOI values up to 38.5 ± 0.4 %O₂ and V-0 classification with excellent self-extinguishing behavior was achieved. Especially gas phase active FRs with lower oxidation states showed better flame-retardant properties in the LOI and UL-94 vertical burning tests with identical phosphorus content. In cone calorimeter test the EVs with 1.5 wt% P reduced the peak heat release rate (PHRR) up to 43 %. The addition of reactive phosphorous-based FRs did not influence the dynamism and recyclability of the material in dynamic mechanical analysis. After mechanical recycling >73 % of the mechanical strength was recovered and the flame retardant EVs do reach as well a V-0 classification in the UL-94 vertical burning test.

Part 1: Recyclability and revalorisation of railway components made of composite materials

Marta Cerdeira Peinado — Wed, 09 Apr 2025 12:58:25 +0200

In the railway sector, represented by TALGO, there is growing concern about the recyclability and reusability of composite parts at the end of their useful life. To address this concern and comply with Spanish and European directives and legislation, an innovation project (divided into "PART 1" and "PART 2") has been carried out in which AITEX, CIDETEC, iTREE, and TALGO have collaborated. The main results of the first part are as follows:

Recycling process of the composite material of the first prototype of the Lightweight Running Gear Frame: This process focuses on recovering the carbon fiber contained in the material by combining several chemical-physical steps.
Development of a 3R (recyclable) epoxy resin formulation: This resin meets the thermal, mechanical, and FST (Fire, Smoke, and Toxicity) requirements of the railway sector and is suitable for use with prepreg technology.

The results indicate that the recycling process is suitable for producing post-consumer parts and that the formulated resin meets the required standards. The overall conclusions of the project will be revealed in PART 2 of this study.

Polymerization kinetics of a recyclable thermoplastic as a matrix for structural composites

Jordi Farjas — Tue, 08 Apr 2025 18:57:23 +0200

In this contribution we have performed the kinetic analysis of the curing process and of its thermal decomposition. Due to the presence of a peroxide initiator, polymerization is a complex process involving an induction period for a fast cross-linking reaction. From the kinetic analysis, we have been able to characterize the induction time and the degradation kinetics. Finally, from the analysis of the volatiles we have determine that the main volatile generated during decomposition is the monomer.

Ionic conductive bio-based composite aerogels

Miguel Sanchez-Soto — Sun, 06 Apr 2025 00:50:23 +0200

In the realm of energy transition, significant advancements are essential on the improvement of energy storage performance as well as in sustainability and safety. Aerogels are lightweight materials that can be endowed with mechanical strength, thermal insulation capability, and fire resistance. These characteristics make them promising for electrochemical devices such as composite polymer electrolytes (CPE). Silica-based aerogels have been used as scaffolds for solid polymer electrolytes (SPE). In these applications, the aerogel not only provides structural support but also creates additional conduction channels that improve ionic conductivity (IC). In this work, we present a bio-based aerogel composed of gelatin, montmorillonite clay, and tannic acid, synthesized using water as a solvent. By employing an ice templating strategy, we achieved a 1D pore orientation, which provides more direct conduction pathways. This aerogel exhibits an axially oriented honeycomb porous structure with high porosity (92.9 ± 0.1%) and low density (0.130 ± 0.002 g/cm³). It is also categorized as a self-extinguishing material. This aerogel was infiltrated with a SPE consisting of Polyethylene glycol (PEG) and Lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). With partial pore coverage, we achieved IC at room temperature on the order of 2 × 10^-7 S/cm. This led to promising results, resulting in a porous (76%) ionic conductive aerogel that opens new perspectives. It enables the creation of a low-density solid electrolyte, which can increase the specific capacity of the final device. Alternatively, it can serve as an active, fire resistant, scaffold for a liquid or gel electrolyte, enhancing and maximizing IC.

Effects of GlyNAC on Tissue Regeneration, Behavior, and Locomotor Activity in Dugesia tigrina

Alexander Lee — Thu, 03 Apr 2025 21:53:23 +0200

This study aims to investigate the effects of GlyNAC on planaria tissue regeneration and behavioral changes. There has been a focus on anti-aging in the older population due to the adverse effects that come with it such as muscle fatigue, a decrease in tissue regeneration, etc. As a result, there was an increase in research on finding an effective supplement to combat health issues and aging. GlyNAC, a combination of Glycine and N-acetylcysteine, has been shown to reverse and improve health by increasing glutathione levels. Glutathione is an antioxidant with multiple health benefits such as protecting against oxidative stress, a main factor in causing cell death. This experiment was conducted using planarians because they have a similar central nervous system, tissue regeneration, and glutathione production to humans. There were 1 control group and 3 experimental groups. The control group was fed regular ground beef while the experimental group was fed ground beef with GlyNAC. For tissue regeneration, each group would be measured and observed before and after the ground beef or GlyNAC-mixed ground beef. The planarians’ motility was recorded for 20 minutes with grid paper underneath their petri dishes. The results indicate that GlyNAC treated groups had increased regeneration and movement. With this support, our hypothesis of GlyNAC increases the regeneration and movement in planarians. Future Research can be done by having bigger experimental groups for more accurate data. Introduction GlyNAC There has been an interest in anti-aging in the modern day due to one’s fear of aging and the many symptoms that come with it, such as muscle fatigue, inflammation, a decrease in tissue

Long-term performance of injection-molded isotactic polypropylene containing weld lines in unfilled and glass fiber-reinforced grades

Aitor Arriaga — Wed, 02 Apr 2025 10:06:44 +0200

The study of weld lines in polymers is far from settled, especially in predicting how materials perform over long periods under stress. While previous research has explored the behavior of isotactic polypropylene (iPP) in both its unfilled and glass fiber-reinforced forms, the focus has been largely on short-term behavior. However, this study shifts the lens to long-term performance under complex conditions, specifically looking at creep and fatigue. We take a novel approach by considering iPP with 30% glass fiber reinforcement, using tensile samples that induce weld line formation. Creep behavior is measured across a broad range of strain rates and temperatures, aiming to understand the underlying mechanisms that govern material failure. These short-term tests are then linked to more comprehensive long-term evaluations, including cyclic loading and creep-to-rupture tests. Crack growth is assessed using CT specimens, enabling us to capture failure modes that are otherwise difficult to quantify. The study goes further by proposing a new way to model deformation. Instead of relying on traditional methods, we turn to the Eyring equation for a more accurate prediction of failure times under cyclic stress, especially as materials transition to brittle fracture at higher temperatures. These predictions match experimental results, demonstrating the potential of linear elastic fracture mechanics (LEFM) in assessing long-term material performance. Ultimately, this research challenges conventional models and provides a pathway for more accurate long-term predictions, a crucial step for industries relying on polymer materials in demanding environments.

Reinforcement vs. sustainability: the future of self-healing and recyclability in elastomeric composites

Marianella Hernandez Santana — Mon, 31 Mar 2025 11:09:35 +0200

This work presents ionically vulcanized carboxylated nitrile rubber (XNBR) compounds reinforced with conventional and sustainable fillers. The impact of adding traditional fillers, such as carbon black and silica, as well as sustainable options, such as cellulose and ground tire rubber from end-of-life tires (GTR), on the rubber's mechanical, thermal, self-healing, and recyclability properties is carefully analyzed. The results demonstrate that the incorporation of sustainable fillers achieves a favorable balance between repairability, recyclability, and mechanical performance. In particular, the compound with GTR exhibits reinforcement levels comparable to those of silica-based compounds, while maintaining full reprocessing and repairability. This study highlights the potential of using sustainable and recycled materials in the rubber industry, significantly contributing to the development of environmentally friendly elastomeric compounds.

Buckling analysis of laminates subjected to biaxial loads using cruciform specimens

Maria del Carmen Serna Moreno — Fri, 28 Mar 2025 21:00:33 +0100

This study presents the compression-compression test with cruciform specimens (test CC) as a viable methodology to assess the geometric instability of a ∓45° symmetric laminate. The central region of the specimen, subjected to biaxial loading, exhibits a geometry similar to that of a square plate fixed along its entire perimeter. The bifurcation of the strains recorded at the top and bottom surfaces of the laminate is considered to be the threshold between the in-plane biaxial response and the response dominated by bending and torsional moments. The nonlinearities observed in the evolution of the stress-strain relationship in the region subjected to biaxial loading are confirmed to be independent of the response of the specimen arms. The bending-torsion coupling effects at the beginning of the bifurcation are observed experimentally in the deflection surface recorded by Digital Image Correlation. The results obtained suggest that the test CC is potentially suitable for the observation and measurement of buckling modes under various boundary conditions. However, more work is needed to reduce the quantitative dispersion. Specifically, the research should focus on minimizing geometric imperfections and load misalignments.

Combined Treatment of Korean Red Ginseng (Panax ginseng) and DHA Outperforms Either Treatment Alone Against Amyloid-Beta Neurotoxicity in a Caenorhabditis elegans Model of Alzheimer’s Disease

Nathalie Zhang — Thu, 20 Feb 2025 06:30:04 +0100

his study investigated the combined efficacy of docosahexaenoic acid (DHA) and Panax ginseng extract for treating Alzheimer's disease (AD). Single-target therapies aimed at clearing amyloid-beta (Aβ) have been largely unsuccessful, shifting attention toward multi-target approaches; among the most promising are DHA and Panax ginseng. Although DHA shows strong efficacy in AD prevention, once neurodegeneration has taken hold, blood-brain barrier (BBB) damage impairs its transport into the brain. Ginseng may counteract this by strengthening the BBB through the Wnt/β-catenin (BAR-1 ortholog in Caenorhabditis elegans) pathway and preventing DHA oxidation via its antioxidant properties, thereby enhancing delivery where it exerts neuroprotective effects. Based on these complementary mechanisms, the present study evaluated whether combined treatment confers benefits beyond either treatment alone using CL2355 (transgenic AD model) and N2 (wild-type) Caenorhabditis elegans. Five experimental groups were compared: two untreated controls (wild-type; AD model) and three AD model groups receiving DHA (5 mM), ginsenoside (10 μg/mL), or both. Treatment effects were assessed through paralysis (mobility), chemotaxis (neurological function), and population growth (reproduction) assays. The combined treatment reduced paralysis by 40% relative to untreated AD worms and 10% beyond either treatment alone, while significantly improving chemotactic function (p<0.01). These results suggest combined treatment holds potential as a multi-target therapeutic strategy, possibly by enhancing DHA absorption by the neurological system and/or targeting AD pathology through compounding mechanisms, though this study cannot distinguish between the two. These promising findings warrant further research using higher-order AD models or assays measuring nervous system DHA absorption.

Effects of nitrogen form on growth rate of the free-floating macrophyte Phyllanthus fluitans: Implications for nitrogen phytoremediation and invasive plant management

Nathalie Zhang — Tue, 11 Feb 2025 02:43:10 +0100

Phytoremediation is a promising method for mitigating nitrogen pollution due to its low cost and generation of biomass that can be repurposed. However, given the risk of plant invasion and the low tolerance to extreme conditions of plants currently used for phytoremediation, broad implementation requires the discovery of new species. This study assessed the phytoremediation suitability and invasive potential of Phyllanthus fluitans, a promising free-floating macrophyte for which no peer-reviewed physiological data exist. P. fluitans is morphologically similar to Lemna minor, the most widely used phytoremediation species, but has the added benefit of larger fronds that reduce wind-driven displacement risk. Plants were placed in 0.002M solutions of ammonium-to-nitrate ratios ranging from 0:1 to 1:0 across two independent trials. Plants receiving solely nitrate exhibited drastically higher fresh weight (p<0.05), dry weight, leaf count (p<0.05), root length, and survival rate compared to all other groups. Ammonium dose-dependently increased mortality, causing toxicity symptoms like chlorosis, necrosis, and stunted growth, resulting in complete die-off in the sole ammonium group. Additionally, the reduction of a mineral supplement between trials revealed P. fluitans to be highly sensitive to elevated water hardness. Collectively, nitrate preference and poor resilience render P. fluitans a poor phytoremediation candidate. However, under optimal conditions, the species can more than double its biomass in 24 days. This indicates that the invasive potential of P. fluitans varies drastically depending on environmental conditions, a finding that environmentalists can use to make condition-specific risk assessments and manage invasions accordingly.

The Effects of Energy Efficient Behavior Reminders on Electricity Conservation in a New York Public High School

Amanda Chen — Mon, 10 Jun 2024 21:03:03 +0200

Excessive electricity consumption negatively affects the economic growth of developing countries, and is a major cause of carbon emissions throughout the globe. This experiment investigated how the use of energy efficient behavior reminder affects electricity conservation in a New York City Public High School. In this experiment, during the first 10 days of the experiment, custodians were not reminded to turn off lights. From Day 11-20, reminders were sent to custodians every Monday and Fridays to turn off the light. During Day 21-30, reminders were sent everyday to remind custodians to turn off the lights. The results showed daily reminders had a significant decrease in electricity consumption compared to when no reminders were sent, but there was no significant difference between the percentage of lights being on, making it difficult to confirm if the custodians followed the reminders. The reminder of turning off lights was not a major source of electricity consumption and other factors might have consumed a larger portion of electricity.. More schools should be studied in order to validate the results. Future studies/research can test the effects of energy saving behavior reminders on electricity conservation from turning off electronic devices, such as smart boards or computers, at the end of the day.

REPAIRING OF STEEL STRUCTURES BY COMPOSITE PATCHES ACTING AS A CRACK ARRESTORS

Lourdes Blanco Salgado — Sun, 01 May 2022 19:58:52 +0200

Today’s merchant and passenger vessels are complex structures that operate in harsh environments with respect to static and cyclic loads and corrosion. Depleting funds for fleet renewal and increasing through-life cost of maintenance and repair are the principal factors that lead to the need to implement new solutions that are easy to apply and low cost. All this added to the growing need for lightening in the transport sector turn the FRP materials into the main candidates as drivers for this change.

This present study within RAMSSES is focused on the compare a damage steel structures to repair composite patches. A representative structural detail of a cruise vessel was selected and designed as a demo case. The best patch solution was selected by FEM calculations, which have been fed from the mechanical test results of the composite material combinations, steel, surface treatments and adhesion joint of the one-shot dissimilar joints without adhesive.

Fatigue tests have been carried out and monitoring by strain gauges and FBGs positioning and distribution in the high stress areas along the demonstrator. Fatigue tests have been carried out in the six demos to compare crack evolution in cracked Patched and Un-Patched demonstrators.

As conclusion after the fatigue tests, composite patch works as crack arrested. Therefore, this behaviour represents an improvement of the 2.6 times of the fatigue life comparing UnPatched and Patched damaged steel.

Performance-Based Optimization of Reinforced Ductile Concrete Frames with Asymmetric Reinforcement in Columns, using the ISR analogy

Luis Fernando Verduzco Martínez — Sun, 05 Sep 2021 20:43:03 +0200

The present work exposes the design of optimization procedures both with the “Particle Swarm Optimization” (PSO) algorithm and the “Genetic Algorithm” (GA) for the design of reinforced concrete frames, making comparisons in cost, weight of the structure and predicted damage. The optimization procedures are built up using the “Idealized Smeared Reinforcement” (ISR) analogy for each element of the structural model frames considered for this work. Two different numerical structural plane-frame models were created for the application and comparison of the performance of the optimization design procedures hereby proposed. The optimization procedures were mono-objective with a cost-objective function, taking on account steel reinforcement and concrete for the cost computation. Two different design approaches were carried on for this work, one proposing asymmetrical reinforcement for columns and the other with symmetrical reinforcement. In order to compute the damage indices considered for this study a non-linear Pushover structural analysis is performed. Results show that asymmetrical reinforcement in columns may reduce concrete volumes, although such reduction in material might not be quite proportional with construction cost, given that asymmetric reinforcement in columns is more expensive than symmetrical, per unit-cost. The bigger the structure, the more likely is to obtain lighter structures by using asymmetrical reinforcement. Regarding damage of the structure, results show that when using asymmetrical reinforcement in columns, it is more likely to obtain smaller values for the expected damage with no great difference on the estimated collapse Safety Factors for the seismic loads. In general, the proposed methodology hereby proposed enhances quite good optima results, requiring only a few adjustments of clash-free and slap reinforcement after the optimization procedure terminates. When designing reinforced concrete frames with asymmetric reinforcement in columns, an increase in construction costs of as much as $25\%$ as that obtained for symmetric reinforcement could be enhanced. In general, with the proposed methodology to optimally design reinforced concrete frames, savings of as much as $20\%$ in construction costs from an initial structural proposal can be reached.

List of Equations in https://doi.org/10.23967/j.rimni.2020.09.001

Dejan Brkić — Sat, 05 Sep 2020 14:50:02 +0200