Colloquiam: Documents published in 2025

Meeting UN's 2030 agenda: Analysis of enablers for energy firms..

Erola Palau Pinyana — Tue, 08 Oct 2024 15:10:04 +0200

Within the framework of the United Nations' 2030 Agenda, this study analyzes the role of the energy sector in achieving the Sustainable Development Goals (SDGs). Through a resource-based approach, it investigates the elements facilitating SDG implementation in global energy companies, distinguishing between renewable energy and fossil fuel firms. Using empirical analysis with data from 522 companies in the sector, the methodologies of Partial Least Squares Structural Equation Modeling (PLS-SEM) and Qualitative Comparative Analysis (QCA) are combined to understand the factors driving SDG implementation in this industry. The results reveal significant differences between renewable energy and fossil fuel companies regarding the effectiveness of facilitative elements, highlighting the complexity of implementing SDGs in the energy sector. This study contributes to understanding how energy companies can leverage their resources and capabilities to align with the 2030 Agenda, providing guidance for change agents in the energy transition.

Nous camins del Patrimoni Industrial de Catalunya: Passat, present i futur

Pere A Fàbregas — Tue, 08 Oct 2024 09:49:03 +0200

El treball presenta la importància de la industria i de la industrialització primerenca en la creació de la Catalunya contemporània, i els esforços realitzats per mantenir aquest llegat, al llarg del temps, amb l’aparició de la Arqueologia Industrial i del Patrimoni Industrial (Industrial Legacy) en el context internacional, com a part rellevant del Patrimoni Cultural.

Planteja la necessitat de reconstruir la industria al país, una industria nova, neta, i arrelada, per assegurar el creixement futur de Catalunya, i la millora de les condicions de vida dels ciutadans. A la vegada que albira els problemes, o oportunitats, de la transformació digital progressivament accelerada, per la preservació futura del Patrimoni Industrial com a recurs bàsic per entendre i explicar el país, i per ajudar a construir una societat més equilibrada i respectuosa amb les seves pròpies arrels.

La relació entre el proveïdor i el finançador com a element determinant de la sostenibilitat del sistema sanitari públic

Francesc Lopez — Mon, 07 Oct 2024 11:49:03 +0200

En relació al seu entorn urbà, un hospital és una organització molt gran. De fet, sovint passa allò que l’hospital és l'empresa més gran del municipi. Però la mida no li dona els atributs propis d’altres organitzacions destacades com un banc: un hospital produeix per valor dels recursos que disposa a curt termini, no pot finançar més despesa que els ingressos que li pertoquen del sistema de pagament que hi hagi, ni pot canviar l'ordenament segons el qual els pacients poden accedir a un servei ni el temps en el qual tenen garantit ser atesos. Amb aquestes dependències, és clar que en funció del que faci un tercer, un hospital pot veure compromès el seu futur en el més curt termini, el que marca el període de garantia per atendre a la ciutadania.

L’ens que ha de garantir que són compatibles els temps de resposta i la capacitat de finançar una determinada activitat és el Departament de Salut i l’organització en qui en delega la compra, el Servei Català de la Salut “Catsalut”, qui a més ha de tenir en compte si els proveïdors podran fer o no l'activitat i de quin és el seu cost per reemborsar-lo de manera continuada i complerta. Des del Catsalut, la suma de totes aquestes compres a centenars de proveïdors és el que determinarà la despesa sanitària i, si incloem la farmàcia d'alt cost, serà el paquet de despesa més gran i decisiu del conjunt del sistema. On resta la seva viabilitat? En la justa correspondència entre la compra i el seu finançament. Aquest equilibri és impossible sense un coneixement exhaustiu de què costa la producció i què costa allò que es vol comprar.

Qualsevol proposta de millora que faci referència a la sostenibilitat del sistema sanitari passa per tenir present com funciona el finançador i com es treballa des dels proveïdors: les decisions que promoguin els primers determinaran no només les accions d'assistència sinó també les d'inversió i de despesa dels segons. En aquest breu text volem aportar una visió de com es pot analitzar de manera global la viabilitat i sostenibilitat del sistema sanitari des del punt de vista del proveïdor. És una mirada parcial però té el valor de ser la del darrer pas, la que a banda de la pròpia provisió incorpora els efectes de les decisions anteriors: la planificació, el finançament i la compra.

Fatigue delamination damage analysis in composite materials through a rule of mixtures approach

Eugenio Oñate — Fri, 04 Oct 2024 14:16:11 +0200

The present study investigates delamination damage initiation and propagation within a homogenization theory of mixtures, using the concept of virtual layers and virtual interfaces. It eliminates spatial discretization of layers, introducing a resultant damage variable to capture structure’s bulk response under both monotonic and cyclic loads. Fatigue-induced deterioration is classified into sub-critical, critical, and over-critical stages based on interfacial stresses. Calibration is conducted employing the widely-available Wöhler curves for each loading mode independently. An advance-in-time strategy is included in the model to enhance the simulation speed. The reliability of the approach is assessed for crack initiation and propagation separately through standard test coupons, showing good correlation with experimental data in mode I, mode II, and mixed-mode loading conditions. Depending on the calibration procedure adopted, the model is applicable to a wide range of stress ratios. In addition, it could be integrated into any standard finite element framework using the desired number of elements through the thickness regardless of the physical amount of layers. This allows easy modification of stacking sequences or the number of layers within the constitutive law without mesh structure changes, facilitating simulation of large-scale composite laminates with minimal accuracy loss and reduced computational costs.

PLA ESTRATÈCIG DE LA FAMÍLIA EMPRESÀRIA

jordi tarragona coromina — Thu, 03 Oct 2024 18:43:04 +0200

Les empreses familiars són la base de l’economia. Tenen voluntat de continuïtat. Conjuguen dues realitats contradictòries: empresa i família.

El Pla Estratègic de la Família Empresària és el procés mitjançant aquesta documenta d’on ve, on està, on va, perquè i com farà el camí. El realitza la mateixa família; la tasca de l’extern és com la de la llevadora. La base és la comunicació empàtica. S’analitza el DAFO de la família i empresa; si el millor és continuar, vendre o tancar; si es vol ser empresa familiar o família empresària; quines són la missió, visió i valors; que s’espera de l’empresa i que s’està disposat a fer per ella; com afectar i formar als continuadors; professionalitzar els sistemes i estructures; planificar la continuïtat i regular les relacions entre empresa i família.

Existeix una metodologia per la seva elaboració i execució.

Aspectes econòmics i financers del servei d'abastament urbà d'aigua

Joan Gaya — Fri, 20 Sep 2024 15:02:04 +0200

En la seva configuració actual, el servei d’abastament d’aigua te el seu origen en l’Estatuto Municipal promulgat l’any 1924. En relació a l’aigua, establia la competència municipal en abastament d’aigua -que era declarada servei públic-, aigües residuals, safareigs, abeuradors i serveis anàlegs. Així es van configurar els aspectes urbanístics que van permetre la generalització de l’abastament domiciliari de l’aigua i la regulació dels seus aspectes econòmics i financers. L’economia de l’abastament d’aigua ha estat molt protegida. En la seva qualitat de servei d’higiene urbana fins fa ben poc s’ha estimulat el consum d’aigua amb polítiques d’oferta i abundants ajuts públics. Així s’ha observat que tot i tenir un valor molt superior al seu cost, el preu al que s’ha subministrat ha estat inferior al cost. Avui tenim la consciència de que l’aigua és un recurs escàs i vivim la situació com una contradicció. El funcionament d’una societat moderna requereix la garantia dels subministraments essencials com ho són l’aigua i l’energia, que és un component d’importància creixent en el cost de l’aigua. La necessitat d’un ajust econòmic d’aquest servei afecta també a l’estructura de costos i ingressos, amb importants asimetries entre els fixes i els variables, que ens han dut a la paradoxa de l’estalvi, és a dir a la inevitable conseqüència de que el resultat d’estalviar aigua és que s’han d’augmentar les tarifes per equilibrar l’economia del servei. En conseqüència cal un replantejament de l’estructura tarifària del servei que garanteixi aquest equilibri i millori la comprensibilitat de la factura per als usuaris. Altres aspectes regulatoris a revisar afecten a la corresponsabilització dels concessionaris en les polítiques de reducció de pèrdues d’aigua del servei, l’encaix econòmic de les polítiques de protecció social que garanteixin el dret d’accés universal a l’aigua o l’adopció de sistemes tarifaris equitatius per a municipis turístics. '''Paraules clau''': aigua, abastament, dotació, costos, tarifa, regulació.

Reforma de l’administració i qualitat institucional

Genèric Congrés2025 — Fri, 20 Sep 2024 12:10:04 +0200

CHAPTER 23: REVALUATION OF RECYCLED REINFORCEMENT FIBERS THROUGH TEXTILE TECHNOLOGIES

Libro Blanco AEMAC — Sun, 15 Sep 2024 19:42:06 +0200

This chapter addresses the environmental and energy challenges posed by the increasing production of composite materials, particularly those reinforced with carbon and glass fibres. Current recycling technologies focused on fibre recovery, such as thermal and chemical methods, now enable the production of fibres suitable for reintegration into the value chain. The chapter details adapted textile technologies for processing these recycled fibres, covering methods from non-woven fabric production to the newest manufacturing technology of yarns and unidirectional tapes. Technologies such as carding and yarn formation are analyzed, highlighting the need for hybridization with virgin materials to enhance the mechanical properties of the final products. While current advances do not yet match the performance of virgin materials, ongoing research continues to optimize these processes, paving the way for the industrialization of more sustainable composites, with applications ranging from lightweight structures to sectors with higher mechanical requirements.

CHAPTER 25: CONCLUSIONS

Libro Blanco AEMAC — Sun, 15 Sep 2024 19:27:03 +0200

Salari mínim, productivitat i mercat de treball - Comunicació breu

Victor Bottini — Fri, 02 Aug 2024 13:09:03 +0200

Autora: Montserrat Cerqueda Serrando, degana del l’Il·lustríssim Col·legi de Graduats Socials de Barcelona, Girona i Lleida.

Eix: 4. El capital humà i el futur del treball. Salari mínim

Justificació paper: El salari mínim interprofessional (SMI) ha augmentat un 54% en els darrers sis anys. Ha passat de 736 € l’any 2018 als 1.134 € l’any 2024. Una mesura que, segons els registres, afectarà a més de 2,5 milions de persones d’arreu del territori.

Un increment com aquest ens hauria de fer pensar en si s’han fet bé les coses durant la darrera dècada i si aquestes pujades actuals són proporcionals a l’augment productiu que estan tenint les empreses. Augmentar l’SMI no vol dir, automàticament, que es redueixin els problemes i les incerteses. Aquest increment tan dràstic en tan poc temps pot suposar un greu inconvenient per les empreses i pel mercat de treball.

Com a graduats i graduades socials, i com experts en Dret del Treball i la Seguretat Social, veiem diàriament els problemes als quals s’estan enfrontant les empreses. Tenir una persona treballadora implica uns costos, així que una pujada tan abrupta de l’SMI en un espai tan curt de temps fa que les empreses pateixin i els seus comptes d’explotació es puguin ressentir.

L’objectiu d’aquest paper és poder analitzar l’evolució que ha patit el salari mínim interprofessional a Espanya, a l’hora que es pugui veure com això està afectant el mercat de treball. Com a professional del dret del treball i la seguretat social, aquesta és una matèria que ens afecta directament i necessitem entendre l’evolució i saber què està passant per poder assessorar correctament a les empreses i a les persones treballadores. L’anàlisi també incorporarà la importància de la negociació col·lectiva per arribar a un consens en matèria d’SMI. A tall d’exemple, a la darrera pujada del salari mínim, el Govern central va arribar a un acord amb els sindicats i va deixar de banda la patronal perquè aquesta no acceptava un augment més enllà d’un 3%. Amb aquesta situació es posa de manifest un fracàs de la negociació col·lectiva que s’hauria d’evitar per no implantar una gestió en base a imposicions d’una de les parts.

Resultats i conclusions: El Premi Nobel d’Economia 2021, David Card, ha arribat a afirmar que augmentar el Salari Mínim Interprofessional no afecta pràcticament l’ocupació. El destacat economista canadenc, durant una de les seves conferències, va posar de manifest com el model alemany, d’incrementar l’SMI, no va tenir repercussió directa sobre l’ocupació, ja que el mercat de treball va continuar amb el seu habitual funcionament.

D’altra banda, augmentar l’SMI està molt bé, però s’ha d’acompanyar amb unes condicions i uns llocs de treball que siguin de qualitat, que permetin crear un teixit empresarial productiu i responsable. Només d’aquesta manera les persones treballadores podran tenir un lloc de feina estable i de qualitat, el que acabarà repercutint en una millor productivitat i, per tant, un millor funcionament de les empreses. A més, incrementar el salari mínim té una correlació directa amb un augment del consum i, per tant, una activació de l’economia.

ANNEX 1: COMPANIES, TECHNOLOGICAL CENTERS, UNIVERSITIES AND AGENTS

Libro Blanco AEMAC — Thu, 25 Jul 2024 21:45:02 +0200

ANNEX 2: LIST OF PROJECTS RELATING TO SUSTAINABILITY

Libro Blanco AEMAC — Sun, 21 Jul 2024 13:09:05 +0200

CHAPTER 20: FAST WARMING AND LOW ENERGY CONSUMPTION

Libro Blanco AEMAC — Sun, 21 Jul 2024 12:46:05 +0200

Many manufacturing processes for composite material structures are based on large and expensive facilities that result in slow, expensive, and energy-inefficient processes. The preforming of dry fiber fabrics, for example, is carried out in large hot drape forming facilities, where conventional heating sources based on infrared lamps are not very efficient, since much of the heat supplied is transferred to the heavy aluminum molds in which the preforming process is carried out. In the current context in which it is essential to reduce the carbon footprint of each component, it is essential to reduce the energy needed in production processes and at the same time achieve competitive cycle times.

In this context, Tecnalia has been working for years on the direct resistive heating technology in order to accelerate and optimize composite material manufacturing processes. The direct application of a current to the carbon fiber material to be processed has the advantage of avoiding the heating and cooling of the molds or other adjacent tools, obtaining the results much more quickly and efficiently than with the methods used until now. In the case, for example, of the preforming process of carbon fabrics, applying heat only to the preform allows reducing cycle times and energy consumption by more than 60% and 80% respectively. This means reducing the cost of the process related to lower energy consumption and shorter cycle time. The quality of the preforms obtained through resistive preforming is the same to that obtained through conventional hot drape forming technology and, in addition, it is a repetitive process that has been validated in industrial manufacturing environment.

The article also indicates that this direct resistive heating technology is not only applicable in carbon fiber preforming processes but could also be used in other manufacturing processes for composite material components.

CHAPTER 19: MATERIALS COMPOSED OF NATURAL FIBERS

Libro Blanco AEMAC — Sun, 21 Jul 2024 12:27:02 +0200

This technical report addresses the study of composite materials with natural fibers as reinforcement. The properties, applications and manufacturing processes of these materials are explored, highlighting their relevance in various industries. The environmental and sustainable benefits associated with the use of natural fibers instead of traditional materials are analyzed, as well as the current issues to overcome.

CHAPTER 14: REUSE OF POLYMERIZED COMPOSITE MATERIALS

Libro Blanco AEMAC — Fri, 19 Jul 2024 18:15:05 +0200

Spain, holding a prominent position in Europe's composites industry and notably in aviation composites, faces significant waste management challenges within its 500-strong composite company sector. As it shifts towards the Circular Economy to enhance competitiveness and resource efficiency, Spain adheres to the EU's waste hierarchy, emphasizing the critical need for waste minimization and the reuse of materials. This transition is particularly vital given the environmental impact of disposing of polymer-matrix composites, especially cured composites, with Europe generating roughly 400,000 tonnes of thermoset composite waste annually, a substantial portion of which is from Spain.

This study delves into the reuse and repurposing of polymer composites, promoting their integration within the Circular Economy to preserve material integrity and value. It showcases innovative repurposing projects in Spain and across Europe, such as transforming wind turbine blades into materials for construction, which demonstrates the feasibility of extending these materials' lifecycles. These efforts align with sustainability goals aimed at waste reduction and resource conservation. However, challenges persist, including matching waste volume and condition with market demands and scaling these practices effectively. The concept of structural re-use, turning cured composite waste into high-value, reusable products, highlights the potential of merging reuse and recycling strategies. Innovative approaches to reuse not only mitigate sustainability challenges but also foster economically viable solutions, marking a significant stride towards sustainable and efficient resource utilization in the composites sector.

CHAPTER 21: REUSABLE AUXILIARY MATERIALS. ALTERNATIVE VACUUM BAGS

Libro Blanco AEMAC — Wed, 17 Jul 2024 22:09:03 +0200

Auxiliary materials are essential elements for polymer composites manufacturing. Each of these elements performs a specific function and requires partícular characteristics depending on the process parameters.

They are generally single-use materials (consumables) and thermoplastics nature, so they could be recovered and recycled. However, due to the manufacturing process of composite parts, this recycling becomes complex due to contamination by resin and fibers and the heterogeneity of the different auxiliary materials.

Because of this, one of the alternatives to reduce the consume of these elements and minimize their environmental impact is to use of reusable auxiliary materials. Currently, there are commercial solutions based on silicones. This alternative must be evaluated for each case, considering parameters such as the number of parts to be manufactured or their size and geometry.

CHAPTER 22: DESIGN CONCEPTS BASED ON LOW CARBON FOOTPRINT CONSIDERATIONS AND METHODOLOGIES, EASE OF SEGREGATION AND RECOVERY.

Libro Blanco AEMAC — Wed, 17 Jul 2024 19:12:03 +0200

In the current context of transitioning towards a circular economy and the digital age, the design of products based on composite materials requires a rethinking of decision-making processes. It is necessary to incorporate methodologies that include sustainability concepts, from selecting materials that can be revalorized to designing a product so that segregation at the end of its useful life is as simple as possible, always ensuring the technical, functional, and safety requirements of the products. This presents a complex scenario that will be elaborated on in the following sections:

CHAPTER 18: REACTIVE THERMOPLASTIC RESINS

Libro Blanco AEMAC — Wed, 17 Jul 2024 19:10:06 +0200

One of the main challenges currently faced by the composite materials sector is to ensure its sustainability, both at the level of the raw materials used, the production means necessary for its transformation, as well as its management and treatment. at the end of its useful life.

Especially critical is the situation of thermostable composite materials, widely used in structural applications due to their excellent performance/weight ratio. There are different fields of research, oriented towards the search for more sustainable alternatives for these matrices so that these high mechanical performances continue to be guaranteed and that they can be transformed by conventional manufacturing processes.

Reactive thermoplastic resins are a sustainable alternative for the manufacture of recyclable, weldable and processable structural composite components by conventional manufacturing technologies (Infusion, RTM. Pultrusion, Fillament Winding)

CHAPTER 17: VITRIMERS

Libro Blanco AEMAC — Wed, 17 Jul 2024 19:08:06 +0200

The development of recyclable plastics is a key focus of research in the current world due to its environmental issues and concerns about non-renewability. Recently, vitrimeric materials have garnered significant attention as an exciting class of renewable plastics due to their potential to exhibit strength, durability, and chemical resistance approaching that of traditional thermosetting plastics, while also demonstrating recyclability at the end of their lifespan. This is attributed to their chemical structure, as vitrimers possess dynamic covalent crosslinking, providing them with stability while being reprocessable. This review summarizes the latest advancements and prospects in the development of vitrimeric materials. Special emphasis is placed on vitrimer design strategies that pave the way for the development of next-generation circular materials. The emerging applications of vitrimers are also discussed in terms of their properties, including self-repair, malleability, processability, and multiple shape memory.

CHAPTER 16: BIO-MONOMERS AND THERMOSTABLE BIO-RESINS

Libro Blanco AEMAC — Wed, 17 Jul 2024 19:05:03 +0200

Thermosetting resins, especially epoxy resins, have historically been based on petroleum-derived monomers, posing problems of toxicity, high costs, and dependence on non-renewable resources. This chapter presents the use of natural plant sources to develop more sustainable resin precursors.

The synthesis of bio-epoxy monomers from vegetable oils, polysaccharides, lignin, polyphenols, and natural resins is currently the subject of interest in several research projects and scientific papers, in some cases reaching the level of product commercialization. Vegetable oils, such as linseed and soybean, and the transformation of saccharides into epoxy monomers are examples of explored options. Naturally occurring epoxy monomers derived from polyphenols from various plant sources can also be found, although their epoxidation requires the use of toxic compounds such as epichlorohydrin.

Several natural sources, such as natural rubber, resin acids, and lignin are examined as alternatives to synthesize epoxy resins of natural origin. Leutelin, recently identified in fruits and medicinal herbs, is highlighted as a promising compound to produce bioepoxy monomers.

Although initially the research focused mostly on the development of monomers of natural origin, research also extends to hardeners of natural origin, highlighting the synthesis of amines from vanillin and curing agents based on phenalkamines. The development of hardeners with reversible bonds, such as lignin imines, is also being explored, and the catalytic effect of hemp fibers in the curing of epoxy resins is highlighted.

The combination with traditional monomers or the development of recyclable resins and vitrimers with reversible bonds are current fields of interest for the development of these resins, especially in the context of their competitors of petrochemical origin.

CHAPTER 15: REUSE OF FIBERS AND RESINS IN STRUCTURAL ELEMENTS. PROPOSALS FOR USE IN DIFFERENT INDUSTRIES: PRELIMINARY PROPOSALS FOR USE

Libro Blanco AEMAC — Wed, 17 Jul 2024 19:04:02 +0200

One of the main problems of composite recyclability, is to find applications with a positive business case and technically viable. In order to determine possibilities, it is necessary, first, to analyze mechanical properties of materials as well as today available manufacturing processes with this type of products.

CHAPTER 13: WASTE MANAGEMENT AND REUSE TECHNOLOGIES OF NON-POLYMERIZED COMPOSITE MATERIALS

Libro Blanco AEMAC — Wed, 17 Jul 2024 18:58:05 +0200

This chapter addresses two relevant challenges to enforce in a manufacturing plant where carbon fiber prepreg is used as raw material for the manufacture of aeronautical parts. The first challenge is the segregation of fresh production waste, where the resin is fresh and has a big potential for being used as material for other applications. This chapter described a proposal for the collection of this highly valuable material in a pilot plant where aircraft stabilizers are manufactured. This second challenge addresses solutions for the reprocessing of waste material discarded during the manufacturing of carbon parts. Hereafter is described the preparation of new materials or by-products, which can be reincorporated into the production system of other composite material parts.

CHAPTER 10: MECHANICAL RECYCLING OF COMPOSITE MATERIALS

Libro Blanco AEMAC — Wed, 17 Jul 2024 18:55:03 +0200

The mechanical recycling of long-fiber composite materials is presented as an alternative of greater technological simplicity as well as low energy consumption, emission of pollutants and use of solvents, which places it in an advantageous position from the point of view of environmental sustainability. However, the products obtained are short-fibered, which reduces their mechanical reinforcement capacity, and have been used mainly as fillers for cementitious, asphalt and thermoplastic matrices.

The technologies used to reduce the size of the initial pieces substantially influence the characteristics of the final product obtained, especially if they are to be used for functional purposes in terms of electrical or thermal properties. In addition, the fibers obtained have a proportion of resin from the initial composite material, so the subsequent treatment processes of these fibers, both physical and chemical, can affect the amount of final resin present in the product, its agglomeration or its surface characteristics.

The current challenges for these products is to find processes that allow a better quality and greater uniformity of the final properties of the short fiber, so that the products obtained present a greater added value, which allows them to compete with other current discontinuous reinforcements.

CHAPTER 12: WASTE REDUCTION IN PRODUCTION AND REUSE OF MATERIALS

Libro Blanco AEMAC — Tue, 16 Jul 2024 23:29:03 +0200

The efforts to reduce, reuse and recycle scrap derived from manufacturing processes with composite materials are significantly increasing in all those sectors making use of such materials in their production systems. The rising commitment with the environmental cause and the everyday stricter regulation in terms of waste management has led to launching new initiatives to minimize the environmental impact of composite materials and derived components manufacturing. Therefore, the aim of this chapter is to provide several examples of optimization initiatives in the use of composite materials and, consequently, the reduction and reuse of waste in production environments in the aeronautical sector, having Airbus as a reference where, according to the available pre-pandemic data, 61% of the scrap corresponds to uncured material whereas 39% refers to cured waste.

CAPÍTULO 11: TECNOLOGÍAS DESTINADAS A LA REUTILIZACIÓN DE FIBRAS CORTAS DE VIDRIO Y CARBONO RECICLADAS

Libro Blanco AEMAC — Tue, 16 Jul 2024 23:10:04 +0200

En este capítulo se describen las diferentes estrategias de reutilización que se pueden llevar a cabo con los materiales compuestos con matrices poliméricas una vez pasados por los centros de reciclaje actualmente disponibles a escala industrial.

El trabajo describe cómo, dependiendo de la naturaleza tanto de las matrices como de las fibras de refuerzo, la reutilización de este tipo de fibras debe estar dirigida hacía un tipo de procesos u otros y cómo, mediante la variación de las tecnologías, es posible dar lugar a productos con una mayor o menor orientación de las fibras. De la misma manera, el capítulo analiza algunos de los procesos de fabricación de materiales compuestos, que pueden afectar a la longitud de las fibras y por lo tanto modificar las propiedades del material final.

De esta forma, se describen las diferentes tecnologías actualmente disponibles y en proceso de desarrollo en España para poder dar una nueva vida a las fibras de carbono y de vidrio, orientadas a retener la mayor parte de su valor añadido y propiedades, como son: reutilización en materiales compuestos termoestables, reutilización como refuerzo en materiales compuestos termoplásticos, reprocesado de la fibra (estructuras de fibra tejidas o no tejidas), reciclado de fibras que todavía estén embebidas, reciclajes específicos según la naturaleza de la fibra.

A lo largo del texto se van recogiendo algunos de los proyectos liderados por entidades españolas con mayor relevancia en el desarrollo de las diferentes tecnologías y, además, al final del mismo se remarcan esos mismos proyectos y otros más en los que se destaca el trabajo realizado por centros, universidades y empresas españolas en el campo de la reutilización y reciclaje de fibras de carbono y de vidrio.

CHAPTER 9: SOLVOLYSIS AND BIOLOGICAL RECYCLING OF COMPOSITES. OBTAINING RAW MATERIALS

Libro Blanco AEMAC — Thu, 11 Jul 2024 20:02:03 +0200

This chapter analyses the chemical recycling technique by solvolysis and by biological recycling, explaining that it involves breaking the polymer chain by using reactive solvents, temperature, catalysts, and pressure in the first case, and enzymes and microorganisms in the second. The situation of both technologies is shown, i.e. the operating parameters found in the literature for each type of polymer. In the case of solvolysis, the companies that are currently commercializing this technology are listed; there are still no companies for the case of biological recycling as its technology readiness level (TRL) is lower than for solvolysis. The chapter ends with recommendations for future developments for both types of solvolysis.

CHAPTER 8: REVALUATION OF PYROLYSIS PRODUCTS

Libro Blanco AEMAC — Thu, 11 Jul 2024 19:45:04 +0200

This chapter describes the physical-chemical properties and market options of pyrolysis oils and pyrolysis gases coming from residual fiber-reinforced plastic materials. The description focuses on the pyrolysis products generated from the two predominant types of resin in these materials, i.e. epoxy and unsaturated polyester, from both production and end-of-life waste. Pyrolysis oils and gases have two potential industrial applications: the petroleum refining and petrochemical industries, and the alternative fuels market, namely, refuse derived fuels (RDF). However, it can be observed throughout the chapter that the physical-chemical properties of these two products are far from the standards currently required by the industry. Finally, the state of the art of the research on the optimization possibilities of these products is presented, highlighting a successful case where the oils are eliminated and hydrogen-rich gases are generated, increasing the economic profitability of the pyrolysis processes applied to this kind of waste.

CHAPTER 7: RECYCLING AND RECOVERY TECHNOLOGIES OF CARBON AND GLASS FIBERS BY PYROLYSIS

Libro Blanco AEMAC — Thu, 11 Jul 2024 19:29:03 +0200

Of all the recycling technologies available for recycling fiber-reinforced composite materials, pyrolysis is one of the most frequently used. This technology allows the recovery of long fibers with good mechanical properties in addition to reusing the resin in the form of energy. This chapter describes this technology, including some variations of it, such as microwave-assisted pyrolysis. It can be concluded that pyrolysis is a suitable technology for the recovery of long fibers, maintaining between 70-95% of their initial mechanical properties. Furthermore, pyrolysis applied to reinforced composites is a technology currently used at an industrial level, both in Europe and in Spain.

CHAPTER 6: MANAGEMENT OF COMPOSITE MATERIALS AT THE END OF USE: CURRENT SITUATION

Libro Blanco AEMAC — Wed, 10 Jul 2024 23:13:03 +0200

This chapter presents a review of the current situation in Spain, in relation to Europe and the world, regarding the treatment of composite materials and their constituents at the end of their life cycle. Such treatment may include landfill disposal, energy recovery (incineration), recycling or recovery of materials as raw materials for the same or other uses, or the reuse or repurposing at the component or subcomponent level. These pathways or processes, along with associated developments and research, are described in greater depth in subsequent sections, while this section provides a general, combined, and particularized review, as much as possible, of the Spanish case. The chapter covers three main areas: a general framework, a section on initiatives and services offered by private companies, and a section on the activities of groups, centers, and entities within the R&D sector. Issues related to legislation, including waste classification, are presented in a specific chapter dedicated to this topic.

CAPÍTULO 5: IDENTIFICACIÓN DE LOS COMPOSITES PARA SU RECICLADO

Libro Blanco AEMAC — Wed, 10 Jul 2024 22:59:03 +0200

Currently, there is a growing interest in the development of reusable polymer matrix composite materials. In this regard, it is commonly known that although thermoplastic matrices can be reprocessed, they generally have worse mechanical properties, and their processing is much more complex than that of thermoset matrices, due to the high viscosities involved during manufacturing processes [1]. Therefore, the development of new thermoset matrices that can be reused is key. In this context, solutions such as polymers based on dynamic covalent bonds emerge, which allow the material to be reprocessed by heating it above its Tg [2], as seen in previous chapters. This would allow reprocessing similar to that of thermoplastic polymers, enabling these composite materials to be used again for new applications.

Therefore, considering the development of these new materials and the existing concerns about developing more sustainable manufacturing techniques and materials, the need arises to establish new methods for the proper identification of both the composite material waste generated and those composite materials that are recycled, i.e., those that are reused. Products can be labeled to facilitate better recovery at the end of their useful life (End of Life, EOL), especially due to the wide variety of possible material compositions in composite materials. Labeling is mandatory for certain plastic products in the automotive industry (including composite materials) according to the End-of-Life Vehicle (ELV) directive [3]. There are standards for labeling products in other sectors. Some high-value products in the aerospace and automotive industries now incorporate Radio Frequency Identification (RFID) tags for tracking product life cycle management (Product Life Management, PLM) and ensuring provenance and traceability. These tags may contain data about the material to facilitate higher-value recycling and could be linked to virtual databases that include material origin, manufacturing, and usage data throughout the entire life cycle.

Proper identification of components can also be done through the Digital Product Passport proposed as part of the ESPR (Ecodesign for Sustainable Products Regulation) [4], to maintain adequate traceability of products in terms of material technical characteristics, repair information, etc., so that consumers have a complete understanding of the materials and their environmental impact, in order to establish appropriate reuse techniques. The ESPR, in turn, aims to design components that result in more reliable, durable, reusable, repairable, easy-to-maintain, recyclable, and energy-sustainable products.

In addition, waste can be classified using EWC codes (European Waste Catalogue). This can enable proper identification of waste that may be more hazardous or waste that could be reused at the end of its first life cycle.

Therefore, this chapter aims to address, in a simple manner, those methods for identifying composite materials, both focused on the traceability of products through digital passports, and for managing the waste generated during their service life using EWC codes.

CHAPTER 4: LIFE CYCLE ASSESSMENT METHODOLOGY

Libro Blanco AEMAC — Tue, 09 Jul 2024 22:22:03 +0200

Life Cycle Assessment (LCA) of composite materials is the use of a systematic approach to assess environmental impacts throughout all stages of the life cycle. This methodology includes defining the objectives and scope of the study, data collection, impact assessment and interpretation of results. This chapter presents the specific considerations for the LCA of composite materials, analyzing related works on this topic. It is concluded that most of the work published to date uses LCA as a tool for comparative studies between traditional solutions (mostly metallic structures) and lightweight composite solutions. The authors observe that there has also been an increase in the use of green or bio-based composites in the recent years, made from natural fibers and/or resins.

CHAPTER 3: SITUATION OF COMPOSITE MATERIALS IN SPAIN

Libro Blanco AEMAC — Tue, 09 Jul 2024 21:45:06 +0200

Composite materials play a very relevant role in various sectors, thanks to the lightweighting they can accomplish. Their implementation has been steadily increasing in recent decades, accompanied by the development of processes and equipment that facilitate and optimize their implementation. Spain is one of the leading European countries in the implementation of these materials and technologies, with leading companies and research centers both in terms of application and technological innovation, which continue to work on expanding the use of composites and advancing their sustainability.

CHAPTER 2: SCOPE OF STUDY AND APPLICATION

Libro Blanco AEMAC — Sun, 07 Jul 2024 18:15:03 +0200

CHAPTER 1: MOTIVATION

Libro Blanco AEMAC — Sun, 07 Jul 2024 17:58:03 +0200

Los pequeños y medianos despachos y firmas de economistas ante el desafío de la información de sostenibilidad y su rol en el servicio integral a las pymes.

Esther Ortiz — Mon, 03 Jun 2024 10:21:02 +0200

Estamos asistiendo a un cambio vertiginoso en la regulación europea, con su traslado a nivel nacional, de la información corporativa de sostenibilidad. Los avances que se están dando en Europa al respecto han servido además como revulsivo para el resto de las normas y marcos de referencia existentes sobre la materia. Además, el debate se extiende no sólo a la revelación de información de sostenibilidad, sino que implica también cambios en el concepto de información corporativa, que engloba a la información financiera. Si bien parecía que estas obligaciones informativas sobre cuestiones ambientales, sociales y de gobernanza (ESG) quedaban restringidas al ámbito de las grandes empresas nada más lejos de la realidad, pues finalmente, de forma indirecta se ven afectas todas las empresas, sea cual sea su tamaño. Por lo tanto, las pymes y los profesionales (economistas) que las asesoran en el ámbito de la contabilidad, fiscalidad y la información financiera en general, juegan un papel fundamental en el camino hacia la sostenibilidad. Por ello, aun no estando las pymes incluidas en el ámbito de obligatoriedad legal de la nueva directiva de información corporativa de sostenibilidad, sí que debido a su claro efecto directo en ellas, vía mercado, cadena de valor y otros, se ha visto la necesidad de desarrollar una norma voluntaria para pymes no cotizadas. En este trabajo exponemos los principales puntos de interés acerca del proceso de desarrollo de esta norma voluntaria de información corporativa de sostenibilidad para pymes no cotizadas, la indudable importancia de las pequeñas y medianas firmas/despachos de economistas en el campo de la información financiera y no financiera en este desafío, y los puntos más importantes de esta norma, sobre la que, entre otros motivos, es vital tener una opinión para participar en el actual proceso de normalización europea de la información corporativa de sostenibilidad.

EFFECTS OF EXTREME FLOODING EVENT ON TRAFFIC LEVEL OF SERVICES IN TUGUEGARAO CITY

RALPH ANGELO ESTILLER — Tue, 07 May 2024 05:26:04 +0200

Land transportation networks such as roads and other transportation facilities underpin socioeconomic development of communities by enabling fast and efficient movement of goods and people from one point to another. However, like any other infrastructures road networks are also vulnerable to natural calamities such as earthquakes and floods that disrupts the natural flow of traffic. In the occurrence of flooding incidents, several road networks are submerged in water making it impassable for traffic especially those located in low-lying areas. In this cases, traffic that were originally catered by these flooded roads will be re-routed to other alternate routes which will then affect the traffic performance of those alternate routes. This study assessed the effect of flooding events on the traffic stream performance measured through its Level of Service (LOS). Greenshields’s linear modelling was used to estimate the maximum capacity of roads based on observed data and the corresponding volume-to-capacity ratio during normal weather condition and using travel survey to estimate the additional re-routed volume to assess the volume-to-capacity ratio during flooding events. The v/c ratio for Enrile Avenue changes from 0.483 (LOS B) to 0.515 (LOS C), while the v/c ratio for Maharlika Highway changes from 0.541 (LOS C) to 1.257 (LOS F), and Lastly, Luna extension’s v/c ratio increases from 0.523 to 0.590, though the LOS remains the same. The researcher concluded that the Level of Service (LOS) in the three selected road sections were greatly affected as their v/c ratio increases. Moreover, formulating and enforcing policies on roadway clearing operations especially on the outer lanes of all major roads could help improve the traffic performance of this roads even during flooding events.

Ports, aeroports and railway system

Daniel Marcelo Piano Bassi — Tue, 30 Apr 2024 13:52:02 +0200

ABSTRACT PREVI

INFRAESTRUCTURES I GESTIÓ SOSTENIBLE DEL TERRITORI

Ports, aeroports i sistema ferroviari

Autor: Daniel Marcelo Piano Bassi

Catalunya es tierra de emprendedores, tierra de pioneros. El progreso se percibe en el desarrollo de los medios de comunicación y transporte, de disponer de una infraestructura que actúe como motor económico del país. Algo realmente muy sencillo de entender. Funciona y funcionó así en todo el mundo. El ferrocarril sobre todo llevó el progreso a todas las regiones a las que llegó. Y, por el contrario, regiones que antaño recibían al ferrocarril y la línea en cuestión fue clausurada, volvió a la situación de atraso que tenía antes de la llegada del camino de hierro. Pasó en Estados Unidos con el trazado del ferrocarril al Far West. El desarrollo de todo el oeste norteamericano no hubiera sido posible sin el ferrocarril.

El grave problema que tenemos en Catalunya es la falta de poder de decisión sobre gran cantidad de temas, regulados por la constitución y que otorga las competencias sobre infraestructuras, entre muchos otros aspectos, al gobierno de Espanya. Entonces esta tierra de emprendedores y pioneros se ve permanentemente castrada, acotada, maniatada y amordazada por los gobiernos de Espanya, tengan el color político que tengan. Desde 1714, en que Catalunya perdió su soberanía política y económica, todas las decisiones de inversión en infraestructuras y consiguientemente de posibilidades de desarrollo, son tomadas por Madrid. Espanya tiene la particularidad de que, en el caso de inversión en infraestructura, las decisiones se toman en clave política y no por la búsqueda de la prosperidad o por una razón de mercado. Muchos prefieren una España pobre, más que una España próspera, si la prosperidad tiene que entrar por los puertos catalanes. La lógica económica llevaría a invertir donde la inversión generara más rendimiento; en cambio, la lógica del poder lleva al Estado a marginar, por ejemplo, el eje mediterráneo, precisamente por su gran potencial.

Pero la decisión política de Espanya es dar largas inclusive a Europa y eternizar la construcción del Corredor Mediterráneo, pese a contar el Estado con la financiación de la Unión Europea, que fue utilizada con otros fines. De la mano del Corredor Mediterráneo va el desarrollo del puerto de Barcelona y otros puertos del territorio catalán ya que se favorecería el transporte marítimo de carga que viene a través del canal de Suez y que ahora descarga mayoritariamente en el puerto de Rotterdam a un coste de flete marítimo muy superior al que los buques cargueros tendrían descargando en Barcelona.

El aeropuerto de Barcelona aspira a convertirse en un hub aeroportuario, pero la decisión, como siempre, la toma Madrid. Hasta el nombre del aeropuerto se tomó en Madrid sin consulta alguna. Para convertirse en hub sería necesaria la ampliación de las pistas del aeropuerto que lo habilite a procesar más aviones de fuselaje ancho y el tránsito de 75 millones de pasajeros/año.

CONCLUSIÓN:

Mientras Catalunya siga dependiendo de decisiones de Madrid, su desarrollo en infraestructuras básicas se verá frenado.

Uses of materials and energy on a finite earth

Carles Riba Romeva — Fri, 26 Apr 2024 20:56:54 +0200

The main objective of this communication is to emphasize that without a new relationship between humans and material resources, it will be practically impossible to achieve the energy transition and mitigate the effects of climate change. The Earth is an open system in terms of energy: it receives radiation from the Sun and emits the same amount of energy into space; however, in terms of material resources, the Earth is a closed system. Nature has the capacity to regenerate in a short time the organic matter of living beings, but not geological matter. The management of the enormous amount of materials of current human civilization (100 Gt in 2022) requires about half of the human energy system and emits 70% of greenhouse gases (half if we excluded AFOLU), of which 2/3 in extraction and obtaining operations. With the end of the fossil era, the management of materials becomes one of the central challenges that will force us to reverse two essential points: the end of a development based on the continuous growth of materials and the replacement of a linear economy based on extract-use-throw with a circular economy. The communication closes with some reflections on the new attitudes and actions that will have to be adopted within the framework of post-fossil sustainable development, where special emphasis is placed on the need to educate.

Treballadors del pensament

Genèric Congrés2025 — Fri, 26 Apr 2024 14:49:23 +0200

The Twin Towers Collapse, Event Analyses and Structural Lessons, Master's Degree Thesis

Alessandro Calvi — Tue, 16 Apr 2024 09:51:04 +0200

This thesis is divided into two parts: in the first part the collapse of the WTC1, WTC 2 (Twin Towers) and WTC 7 buildings following the terrorist attacks of 11 September 2001 is analysed. In the second part, the collapse type and strength of frame buildings with different topological characteristics. What links the two parts is structural robustness.
Below is an overview of the work with a description of the topic covered in each Chapter.
Chapter 1: description of the structural and fire protection characteristics of the WTC 1, WTC 2 and WTC 7 buildings.
Chapter 2: timeline of the terrorist events of September 11, 2001.
Chapter 3: description of the types of fire, the performance of structures and the behavior of the main building materials (steel, concrete) to fire.
Chapter 4: analysis of the main hypotheses of the collapse of the Twin Towers present in the literature.
Chapter 5: definition of structural robustness, structural toughness, vulnerability. Description of project strategies to prevent progressive collapses.
Chapter 6: measurement of the structural strength of buildings with a reinforced concrete frame structure. through Discrete Element simulations (DEM).
Chapter 7: discussion of progressive collapse due to impacts from an analytical and bibliographical point of view.

Automation of the dry fibre deposition process to manufacture structural parts for the automotive sector

Luis Carral — Wed, 21 Jun 2023 09:04:03 +0200

In recent years, lightweight structures have gained importance due to increasingly stringent environmental legislations. This situation is especially critical for the transport sector and, especially, for the automotive sector where, in parallel, there is a strong competitiveness. In this context, it should be noted that traditionally manufacturing processes for structural composite materials involver high TAKT times, which has limited their implementation. Thus, the resin transfer molding manufacturing process and, more specifically, its recently developed thermoplastic version (TP-RTM) has been identified as a route with great potential for mass manufacturing.

Within the framework of the European LEVIS project, the development of a suspension arm made entirely of composite materials has been studied. This study focuses on the development of the process window of the preforming stage, one of the most critical for the development of complex geometries. In this sense, automated taping technology has broken few years ago, allowing the improvement of robustness and productivity. Specifically, a wide range of materials has been studied and important parameters such as fibre deposition pressures and temperatures have been analysed. On the other hand, to optimize the TP-RTM, several aspects have been studied, such as viscosity of the resin, the curing cycle of the resin, the compatibility of the resin, the curing cycle of the resin with the dry fibre and the study of the optimal parameters for the resin injection.

Manufacturing of Thermoplastic Composite Upper Wing Skin by In-situ consolidation (ISC)

Eduardo Lorenzo Villafranca — Mon, 05 Jun 2023 15:49:05 +0200

The OUTCOME Thermoplastic Upper Skin consortium is a European project framed within the Airframe ITD research platform of CleanSky2, funded by the EU's Horizon 2020 program. It is focused on developing, manufacturing, and validating a thermoplastic composite upper wing skin for future application in Airbus Defence and Space transport aircraft.

The upper skin consists of a stiffened panel of approximately 4 meters in length, with six integrated stringers. These elements were joined through a co-consolidation process, where they were welded simultaneously with the tape layup of the skin using In-Situ Consolidation (ISC). The integrated stringers were manufactured in a previous stage using an oven consolidation process. The skin lamination was carried out through ISC using an automated tape laying equipment such as AFP MTorres, assisted by a laser and utilizing PEEK APC-2/AS4 material with a ¼" tow width.

Throughout the project, a campaign of structural tests was conducted to obtain the mechanical properties and allowable values for the design of the outer wing box's upper skin. Detailed and subcomponent specimens (stiffened panels) were also designed, manufactured, and tested with the aim of validating the design, analysis methodology, manufacturing method, and quality control procedure. The activity will conclude at the end of the year with the ground structural testing of the wing box, of which the element is a part, completing the testing pyramid.

New technologies in chemical recycling of composites: catalysis and sizings

Andrés Luengo — Fri, 02 Jun 2023 15:06:04 +0200

The recycling of composites by pyrolysis is a technology still under development, and although it is beginning to be implemented, it still poses different problems to be solved to ensure its viability and profitability. Thus, key aspects such as the high energy consumption of the process, the search for commercial outlets for secondary products, as well as maximising the value of the main products, understood as the reinforcement fibres of the composite itself, must be tackled. Regarding the reduction of energy consumption, AIMPLAS is working on the use of microwave radiation as a more efficient source of energy than convection heating, studying the possibility of reducing the temperature of the process, analysing the effect of this radiation on the quality of the fibres obtained and the final mass balance of the different fractions. Additionally, AIMPLAS has worked on the study of the application of sizings, mainly in carbon fibres. AIMPLAS is working on the development of new products and the optimisation of the application method to obtain short fibres coated with sizings, showing the improvement in the mechanical properties of the final composite due to a better interaction with the resin.

Influence of aging type on adhesive joints in carbon fiber-reinforced epoxy composites

Paula Vigón — Wed, 31 May 2023 13:44:03 +0200

This study analyses on comparing the static delamination behavior and mode I fracture toughness of two types of adhesives (one epoxy and one acrylic) used in a composite material with an epoxy matrix and unidirectional carbon fiber reinforcement. The material was subjected to two different degradation processes (hygrothermal and salt spray chamber), and then mode I fracture was evaluated for both materials.

The results suggest that hygrothermal exposure may have a moderate impact on the delamination behavior of the epoxy adhesive, while exposure to the salt spray environment may result in a significant loss of its delamination resistance. For the acrylic adhesive, hygrothermal exposure improved its delamination behavior, while exposure to the salt spray environment had a minor impact on its behavior. Overall, it is concluded that the type of aging has influence on the fracture behavior of both adhesives.

On the influence of ply thickness and staking sequence in the Free-edge effect

J. Martin — Wed, 31 May 2023 09:50:03 +0200

The edge effect in composite materials is a phenomenon associated with the anisotropy of these materials, generating interlaminar shear and tensile stresses and delaminations at the edges of the panels. This fact was studied by Pipes and Pagano in 1973, obtaining a solution to solve the problem with certain application limitations. This document aims to show a solution to the problem based on the studies carried out since then and use a method capable of evaluating these interlaminar forces, as well as a preliminary failure criterion associated with it. Different parameters can be evaluated such as the thickness of the sheets, the combination of materials or different laminate sequences.

Buckling of circular cylindrical shells under in-plane and/or pressure loads

J. Enrique Herencia — Wed, 31 May 2023 07:36:03 +0200

This work presents a semi-analytical approach to calculate rapidly but accurately the buckling onset of metallic and composite circular cylindrical shells with various boundary conditions under in-plane and/or pressure loads by the Rayleigh-Ritz method. Results are compared with analytical solutions and detailed finite element models reported in the literature. The proposed approach allows a quick buckling analysis of circular cylindrical shells, which makes it an ideal candidate to be used as part of an optimization scheme and/or to reduce potentially the number of detailed finite element models employed in the early design phases.

Characterization of composite material at cryogenic temperatures of 20K and the influence of hydrogen on its mechanical properties

Malte Frovel — Tue, 30 May 2023 18:59:04 +0200

The use of hydrogen as an energy source is a promising strategy to replace fossil fuels, in addition to batteries and biofuels. The European aerospace industry is already working on the development of propulsion technologies with low or zero emissions and heavily considers hydrogen technology. It is favoured in aeronautics to store H2 in liquid form, LH2, at temperatures of 20K to have the highest possible energy density of the fuel. This means that all materials in contact with LH2 need to be characterized at this temperature.

INTA began to carry out cryogenic tests on composite materials 27 years ago. Initially in the field of characterization of composite materials for tanks for reusable launchers. Later, the structural monitoring of LH2 tanks, the detection of hydrogen leaks and fuel cells have also been investigated. Currently, INTA is involved in the characterization of composite materials in LH2 tank projects and the composite material structures that these tanks carry for sustainable aviation.

The article gives an overview of the activities carried out in the field of cryogenic tests of composite materials and provides data obtained in these tests, comparing the behaviour of different materials and different types of tests. In addition, the new lines of research that are being carried out at INTA in the characterization of composite materials and their behaviour before and after being in contact with hydrogen will be explained.

Composite plate buckling. Best practices in Airbus Commercial

Alberto Montes Salmeron — Sun, 28 May 2023 22:11:03 +0200

During the last 20 years computational progress has significantly increased the capacity to determine the behavior of structures under complex loading conditions through finite element models analysis. This computational power can be used to build complex detailed finite element models but also to resolve more complex equations which were not possible to be coded before. Accurate buckling prediction is still a key factor on optimized structural designs. The accurate determination of the onset of buckling is absolutely essential to determine the initial point of instability and the subsequent post-buckling capability. Determining if the buckling will lead to immediate failure or the loading will be able to be redistributed afterwards is a major point to be considered. Designing a structural component with loading redistribution capability optimize the weight and increase the accuracy, so is a key objective of designers on structural components like torque boxes or fuselage skin. During years Airbus has been focused on developing accurate buckling predictions from close form solutions to complex energy methods development. This paper aims to summarize the evolution of such methods with special emphasis in energy methods and the best practices followed in Airbus for development. On top a summary of potential room for improvement and further evolution will be proposed.

Experimental study of the importance of fiber breakage in the resistance of thermoplastic matrix composite materials subjected to compression after impact

Fernando Naya Montáns — Fri, 26 May 2023 11:46:03 +0200

The post-impact strength of composite materials is one of the main design parameters of aeronautical structures in terms of damage tolerance. During the low-velocity impact test, from a threshold energy, the laminate only partially returns the energy received during the impact to the indenter (elastic recovery). The remaining energy is absorbed by the laminate and dissipated in the form of damage (interlaminar and intralaminar), plastic deformation of the polymer matrix and breakage of the carbon fibers. To date, few authors have attempted to quantify the participation of each of the damage mechanisms in the overall energy absorption process of the laminate due to their experimental difficulty. In this work, a methodology has been developed capable of performing damage of similar extent and location to that produced in a low-velocity impact, but without damaging the fibers, through the application of local induction heating. For this purpose, the residual strength and stiffness of AS4/PEEK laminates, subjected to impacts over a wide range of energies (30-70J), have been compared with those obtained in laminates damaged by electromagnetic currents, for equivalent damage extensions. The results reveal that the breakage of carbon fibers has a great influence on the loss of stiffness of the laminate, but not on its strength, confirming the role of delamination as the main responsible for the loss of the strength capacity of the damaged material.

Intralaminar fracture characterization tests at high strain rates

Adrian Cimadevilla Diez — Fri, 26 May 2023 10:40:04 +0200

The behaviour of composite materials under dynamic loading conditions has been a subject of research for the last two decades. When subjected to dynamic conditions, composite materials show a significant sensitivity to strain rate. This is critical for a correct simulation of the behaviour of composite structures under impact. Currently, a few studies have been carried out on the analysis of strain rate sensitivity of the fracture toughness. These studies have reported different conclusions for the same material (IM7/8552), indicating that the optimal technique for characterising this property under high strain rate loading remains unresolved. In this work, it has been carried out dynamic characterization test on the fracture toughness using the Split Hopkinson Pressure Bar. It has been developed a new methodology for obtaining an accurate synchronization between Hopkinson bar data and high speed camera. Using the proposed methodology a good repeatability has been obtained for dynamic tests.

Design and manufacturing of thermoplastic curved fuselage panel for Large Passenger Aircraft

Isabel Martín — Sun, 21 May 2023 22:22:03 +0200

Due to the huge interest of the aeronautic industry for finding new solutions in terms of processes and materials to improve performances and to reduce costs, thermoplastic composite materials appeared as an attractive solution. The high temperatures required for processing this kind of materials and the lack of knowledge in the associated manufacturing processes make their application to structural parts more complex compared to that of thermoset composite materials. The study presented here contains the design and manufacturing of a curved section of a fuselage reinforced with omega stringers and ‘Z’ curved frames. The requirements for designing were taken by considering a preliminary flat demo which was manufactured and tested. Following the manufacturing activities conducted with the flat demo, the stiffeners were obtained by hand lay-up and hot press forming, afterwards they were installed in a tooling with specific cavities and the skin was laminated on top. The lamination of the skin was conducted by using a gantry style machine from the Spanish supplier MTorres. The adhesion of the skin to the stiffeners was possible by increasing the temperature to melting point by using a diode laser. After laminating the skin, the whole demo was demolded and inspected by non-destructive testing, showing a good quality in terms of the skin consolidation and in the welding line with the stiffeners. This work was developed as part of LPA project (Large Passenger Aircraft) in the framework of the Clean Sky 2 JU program.

Resistance welding of thermoplastic composite: from laboratory optimization to scale-up on a fuselage demonstrator

Soraya Pintos — Sun, 21 May 2023 19:43:05 +0200

Future aircraft manufacturing factories are moving towards more flexible and adaptable manufacturing systems that enable shorter manufacturing cycles, environmental friendliness, energy efficiency, and higher productivity. A global aeronautic trend to face this challenge includes the replacement of metal parts with composite counterparts with emphasis on thermoplastic composites (TPCs) for their unique ability to be recycled, reprocessed, and welded. Aiming to commit to the drastic projected increase in aircraft production rates, WELDER project, focused on the next-generation MultiFunctional Fuselage Demonstrator (MFFD), has promoted the development and investigation of highly integrated and robotized manufacturing technologies that needed to be scaled up from a laboratory to an industrial environment. To contribute to such an advance, resistance welding was investigated in this work and successfully automatized for fuselage components assembly.

Welding investigation, including process maturation, parameter optimization, and scale-up analysis was performed at laboratory using LM-PAEK/CF composites. A resistance welding Heating Element (HE), made of stainless steel metal mesh and embedded in glass fiber scrims, was first designed and manufactured using a hot press. The HE, priorly characterized by electrical analysis, was adopted, in conjunction with a lab-scale welding head, to optimize and define appropriate processing times (welding and cooling), welding power, and pressures for the welding of the composite parts. The welds were characterized by visual inspection, microscopy analysis, and mechanical tests (SLSS tests - AITM 1-0019). Once materials and processes were optimized, they were scaled up to finally perform the welding of the frame couplings into MFFD.

Implementation of a void formation and transport computational framework with applicability to liquid composite moulding

João Machado — Sat, 20 May 2023 18:52:03 +0200

The inclusion of reliable void formation and transport models in process models for LCM is paramount to guarantee the reliability of the manufactured parts, since it allows the estimation of part in-situ void content after mould filling, as well as the estimation of the ideal bleeding time.

The incorporation of void dynamics into mould filling simulations has traditionally been under the form of unsaturated flow, where a continuous saturation field is advected. However, these models lack the prediction of the morphological properties of voids, which are known to influence their mobility through the reinforcement, as well as the final part mechanical properties. Also, direct numerical simulation methodologies, which are fundamentally based on the Volume of Fluid (VoF) method, can provide void morphological data but are too computationally expensive to apply directly into an entire mould filling domain.

Particle tracking methodologies have extensively been used in computational fluid dynamics (CFD), to solve problems in which the fluid flow carries solid particles, such as in sediment deposition. This methodology could prove to be a computationally efficient way to deal with the different void morphologies registered, both during void generation, as well as transport, since each void is taken as a discrete particle, thus possessing its own set of properties.

As of today, mould filling simulation software do not encompass such a methodology to allow mould design optimization. This work discusses the implementation of such a methodology, envisioning a streamlined application into process design.

Experimental and numerical analysis of the response of a carbon fiber composite material to an explosion.

Ramón del Cuvillo — Sat, 20 May 2023 17:09:03 +0200

The aeronautical industry, in its search for more weight-efficient solutions, increasingly uses composite materials due to their specific properties. However, these are vulnerable to loads perpendicular to their lamination plane. Due to these vulnerabilities, numerous studies have tried to evaluate the threat of different states of perpendicular loading, there are numerous studies of high and low velocity impacts of rigid projectiles, the impact of non-rigid projectiles such as birds, ice, etc. have also been studied. or rubber like that of a tire. However, the study of impulsive loads on composite materials is very scarce.

In this work, a combined experimental/numerical study is presented to evaluate the response of a fabric-type CFRP to shock waves, representative of impulsive loads due to explosions. The experimental tests were carried out at the so-called 'SIMLab Shock Tube Facility (SSTF)', at the Norwegian University of Science and Technology (NTNU). Laminates were tested at different pressures to investigate their behavior from an elastic response to total failure. In addition, two high-speed cameras were used to obtain, with the 3D-DIC methodology, the displacement fields. In order to study the internal damage produced in the laminates, non-destructive ultrasonic inspection techniques were used.

To reproduce the behavior of the laminates, a continuous damage model was used, which takes into account the intralaminar damages of the composite material such as fiber breakage. Interlaminar damage was modeled using cohesive surfaces.

Análisis numérico del efecto de la velocidad de deformación en laminados CFRP tipo tejido con agujero

José Manuel Rodríguez Sereno — Fri, 19 May 2023 18:15:05 +0200

Eventualmente las estructuras aeronáuticas pueden estar sometidas a eventos de impactos como los que pueden ocurrir durante un aterrizaje de emergencia o un accidente aéreo. En estos sucesos es necesario poder predecir el comportamiento de las estructuras sometidas a procesos dinámicos para poder asegurar la seguridad e integridad de las mismas. Dado que en la actualidad una gran parte de las estructuras se realizan en materiales compuesto es necesario definir un sólido conocimiento de cómo éstos se comportan bajo cargas dinámicas o procesos a altas velocidades de deformación. Siendo el estudio de laminados compuestos de fibra de carbono (CFRP) a altas velocidades de deformación uno de los principales desafíos en la industria aeronáutica. Varios investigadores han estudiado el efecto de la velocidad de deformación en laminados CFRP de estructura tipo tejido mediante el sistema experimental de barras Hopkinson (Split Hopkinson Pressure Bar - SHPB). Sin embargo, la comunidad investigadora aún no ha llegado a un acuerdo para encontrar una metodología sólida que describa con precisión la respuesta ante elevadas velocidades de deformación de los laminados CFRP tipo tejido. Es más escaso aún el número de estudios acerca del efecto de agujeros en régimen dinámico para describir el efecto del factor de concentración de tensiones. Aunque muchos estudios han desarrollado simulaciones numéricas para analizar el proceso de fractura en CFRP basándose en las teorías de la mecánica de fractura, hay poca información sobre la dependencia de la velocidad de deformación en laminados de CFRP tipo tejido con agujero.

En este trabajo, se propone un modelo constitutivo para describir el comportamiento mecánico de los laminados de tejido CFRP sometidos a compresión dinámica, incluyendo la dependencia de la velocidad de deformación. Finalmente, se ha realizado una modelización numérica utilizando el software Abaqus/Explicit de ensayos a compresión en muestras de laminados CFRP con agujeros, a diferentes velocidades de deformación (cuasi-estáticas y dinámicas) utilizando diferentes orientaciones de las fibras. Los resultados de las simulaciones han sido validados en base a los resultados de una campaña experimental.

Thermal induced stress analysis in type V CFRP pressure vessels for cryogenic applications. (Análisis de esfuerzos térmicos inducidos en recipientes a presión tipo V para aplicaciones criogénicas)

Paulo Teixeira Goncalves — Fri, 19 May 2023 18:14:14 +0200

During the manufacturing of thermoset-based Carbon Fiber Reinforced Polymers (CFRPs), micro-residual stresses are developed within the material due to the different chemical-thermal-mechanical properties of the fiber and the polymer. Considering cryogenic applications, the temperature change from ambient temperature to operating conditions (for example in liquid nitrogen which is at -196°C) involves a temperature change of more than 300°C considering curing temperature from manufacturing. This temperature change develops micro-residual stresses and ply residual stresses that could trigger premature transverse failure or micro-cracking, reducing the effective mechanical performance of the pressure vessel. In this work, a 3D finite element model of the CFRP pressure vessel is developed considering a discretization at meso-scale level, with the actual ply stack orientations and thickness profiles to study the thermo-mechanical residual stresses and the remaining pressure load carrying capacity at cryogenic conditions. The material model was calibrated with experiments on the unidirectional composite at ambient temperature, and cryogenic temperature. The results show that the thermo-mechanical residual stresses can achieve more than 50% of the ply transverse strength, pressure load carrying capacity is reduced and premature transverse failure can be triggered if these effects are not considered during design.

Durante la fabricación de polímeros reforzados con fibra de carbono (CFRP) termoestables, se producen esfuerzos micro residuales dentro del material debido a la disimilitud entre las propiedades termo mecánicas y químicas entre la fibra y el polímero. En aplicaciones criogénicas, la variación de temperatura desde la temperatura ambiente hasta la temperatura de operación, donde por ejemplo el nitrógeno líquido que está a -196°C, implica un cambio de temperatura de más de 300°C considerando la temperatura de curado. Este cambio de temperatura desarrolla tensiones micro residuales, y tensiones residuales en las láminas que pueden activar prematuramente mecanismos de falla transversal o micro fisuras, reduciendo el rendimiento efectivo del recipiente a presión. En este trabajo se desarrolló un modelo 3D utilizando elementos finitos del recipiente a presión de CFRP, considerando una discretización a nivel de meso-escala, con las orientaciones reales de las láminas y de los perfiles de espesores, para estudiar las tensiones residuales termo-mecánicas y la resistencia remanente en condiciones criogénicas bajo presión interna. El modelo de material se calibró con ensayos experimentales del material compuesto unidireccional a temperatura ambiente y a temperatura criogénica. Los resultados muestran que las tensiones residuales termomecánicas pueden alcanzar más del 50% de la resistencia transversal de la lámina, y es posible obtener una falla transversal prematura en la lamina del compuesto si no se tienen en cuenta estos efectos durante el diseño.

Characterization and properties of bio-aerogels composed of gelatin.

Miguel Sanchez-Soto — Fri, 19 May 2023 16:52:03 +0200

Aerogels are low density foam-like materials that are obtained from a sol-gel process in which the solvent used is replaced by air without collapsing the previously formed three-dimensional structure. In this work, we have studied the properties of aerogels composites that have been generated only from natural substances, using gelatin as matrix, clay and tannic acid as modifiers and water as unique solvent. The aerogels were obtained through lyophilization. While pure gelatin aerogel behaves like an elastic and low-stiffness foam, the addition of tannic acid and clay allow obtaining high resistant foams, reaching of up to a 9-fold increase in the elastic modulus, maintaining very low densities ( 0.14 g/cm3). These increases were obtained, on the one hand, due to a change in the aerogel micro-structure that evolved from a layered towards a honeycomb one. On the other hand, the alkaline conditions employed lead to the oxidation of tannic acid that was then able to establish covalent bonding with the amino groups of gelatin. The presence of well-dispersed clay in the matrix significantly reduced the rate of thermal degradation of the compounds due to its rearrangement into a stable protective layer on the surface of the material. Under conditions similar to those developed in a fire, the compound exhibited low flammability and high resistance to the spread of fire thanks to the synergistic action between clay and tannic acid. The achievement of multifunctional properties in these natural aerogels, allows broadening its applications, making that eventually, can replace traditional petroleum-derived foams, such as polyurethane, polystyrene or phenol-formaldehyde that have a notable environmental impact.

Ultrasound-assisted compounding extrusion to improve dispersion of nanoreinforcements

Gaston Francucci — Fri, 19 May 2023 16:27:03 +0200

The addition of nanoparticles can significantly improve the properties of polymers. However, the industrialized production of nanocomposites presents the technological challenge of correctly dispersing the nanoparticles in the polymer matrix. EURECAT has developed a device that can be connected to standard twin-screw extruders and provide ultrasound vibration to the molten material, thus aiming to improve the degree of dispersion of nanoparticles. The present work presents the experimental validation of this technology, including the construction of processing windows and the comparison of nanocomposites obtained by traditional compounding and ultrasound-assisted extrusion. The produced nanocomposites consist of 94% polypropylene and 6% nanoclays (Cloisite 20A). The properties analyzed are: fluidity (MFI), mechanical properties (traction), O2 barrier properties and microstructure (TEM). The MFI results and the increase in material stiffness suggested an improvement in nanoparticle dispersion when using the ultrasonic device, especially when the intensity was set to 60%. These observations were verified with the results of the barrier tests (to O2), which demonstrated that the ultrasound treatment was effective in reducing the O2 permeability of the compounds.

Development of bio-based fire retardant additives and study of their incorporation into epoxy matrices for the mobility and construction sector

Antonio Gonzalez-Jimenez — Fri, 19 May 2023 14:32:04 +0200

This study aims to develop innovative flame-retardant additives from renewable resources, which will ensure high fire protection, low environmental impact, low toxicity and good processability in conventional polymer manufacturing processes in bio-epoxy matrices.

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).

New materials for additive manufacturing based on recycled composite

Andrea Torre Poza — Fri, 19 May 2023 09:34:09 +0200

LMPAEK/CF laminates collected from scrap waste of Automated Fiber Placement (AFP) manufacturing were recycled obtaining different fiber sizes. The fraction with the smallest average particle size was mixed with different concentrations (5, 10, 20, 30% wt.) of PEKK (60:40). Blends processability was assessed by means of differential scanning calorimetry (DSC) and rotational rheology. Lastly, the mixture with 5%wt of carbon fiber content and PEKK was used for the filament manufacturing. This filament was printed in a robotized cell equipped with a 6-axis robotic arm using a printing head with a 0.8mm nozzle. The mechanical characterization of the printed samples revealed a significant improvement in the mechanical properties compared with neat PEKK or LM-PAEK.

3D printing by direct ink writing of graphite electrodes using whey as sustainable binder

Pablo Rodríguez Lagar — Fri, 19 May 2023 09:15:03 +0200

Traditionally, electrodes are produced by coating slurries of porous carbon powders on thin metallic plates. With the development of additive manufacturing technologies, new production methods have been studied in the literature that are intended to the fabrication of 3D electrodes with geometries that offer advantages in terms of easing the different transport phenomena involved in electrochemical processes. However, the low mechanical strength of the 3D electrodes hampers their applicability. This study introduces a novel method for producing graphite/graphene oxide electrodes that possess adequate flexural strength. The proposed method involves using whey, a sustainable by-product of the dairy industry, as a binder. The electrodes are made by direct ink writing (a room temperature extrusion 3D printing technique) which allows the manufacture of 3D structures by overlapping layers of material filaments. By using this technique, electrodes with geometries tailored to satisfy the specific requirements of the application can be prepared. Specifically, we have developed electrodes for water splitting with complex geometries in which the active surface area is enhanced and that guarantee a quick release of the bubbles formed in the reaction, thus avoiding the problems related to mass transport associated to conventional, flat electrodes.

CHARACTERISATION OF MODE II INTERLAMINAR FRACTURE UNDER FATIGUE

Ainhoa Arrese — Thu, 18 May 2023 17:01:04 +0200

It is essential to understand the behavior of composite laminates against fatigue crack initiation and growth in order to accurately predict component service life and to establish safe maintenance periods.

In this work, an extrapolation procedure to characterize the mode II fatigue behavior based on the J_0i-C_0i and Δ_0i-C_0i master curves is presented and validated.

The extrapolation procedure, based on the compliance variation, assumes that all effects associated with damage are included in the equivalent crack length. In this method, new factored expressions for flexibility (C_0i), Integral-J (J_0i) and crack tip displacement (Δ_0i) are defined and according to their polynomial expressions with respect to the equivalent crack length, invariant relationships between J_0i-C_0i and Δ_0i-C_0iare obtained for a given material system and test configuration.

Once the master curves have been calibrated, the extrapolation procedure allows characterizing the fatigue behavior of a material system by determining the Paris law during the fatigue test, monitoring only the test flexibility and the maximum load with respect to the number of cycles.

Characterization of composite joints welded by electrical resistance. Effect of processing parameters.

Marta Herrera — Thu, 18 May 2023 13:46:24 +0200

One of the main advantages of using reinforced thermoplastic materials is the possibility of joining different parts by welding. Welding process avoids the use of mechanical joints, which increase the weight of the component and the manufacturing time; as well as adhesive joints, where it is difficult to ensure their quality.

Welded joints are of special interest when applied in assembly processes with a high production rate. However, welded joints on high-rate components require research into new materials, processes, and inspection techniques. In this line, the present work analyzes the results obtained from different welded joints through heating by electrical resistance without contact. This characterization study includes mechanical, microstructural and physical-chemical properties analysis, as well as its evaluation through non-destructive inspection techniques. As a result, a deeper knowledge of the materials and processes has been obtained, including the effect of the different welding processing parameters.

Different opening mode mechanical tests are presented in this study, as well as thermal analysis by differential scanning calorimetry to evaluate the effect of temperature and time applied during the welding process on the final properties. The quality of the process in the different joining elements has been verified with inspection by means of infrared thermography, correlating indications in the level of IR radiation with localized variations microscopy features (i.e.: amount of resin). In addition, a microstructural study has been carried out to assess the fiber/resin content of the material in the joint areas, as well as a complementary analysis using computed tomography and ultrasound.

Synthesis of hybrid acrylic-polyurethane biobased systems for adhesive applications

Raquel Rodriguez — Thu, 18 May 2023 12:29:05 +0200

Hybrid acrylic/water-based polyurethane systems have been synthesized by a polymerization process in which acrylic monomers have been used as solvents in polyurethane systems. The polymerization has been carried out in four main stages The first stage in which a prepolymer has been obtained, a second stage in which the chain extension has been carried out. In the third stage has obtained the phase inversion and finally in the last stage has been carried out the synthesis of acrylic monomers. Polymerization was monitored by ATR-FTIR and gravimetry. The effect of incorporating a bifunctional chain extender and replacing a conventional PPG polyol with two types of commercial biopolyols (Priplast 1900, 48% renewable and Priplast 3294, 100% renewable) was analyzed. It has been proven that the addition of a second bifunctional chain extender improves the adhesive properties of the hybrid system, an effect that is enhanced by the use of biopolyols. It has been proven that the use of bio-based polyols is possible since they do not significantly reduce thermal properties, making it feasible to obtain a material with 20% renewable content.

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.

Analysis of composite beams using reduced order modeling

Raul Rubio — Wed, 17 May 2023 16:44:04 +0200

Beam-like components help to provide structural integrity in a wide range of applications. Initially made of alloys or natural materials such as wood, today’s technologies like pultrusion make possible the manufacturing of such components with composite materials providing good quality products with high performance to weight ratio. The anisotropic nature of composite materials, though, poses a challenging framework when numerically simulating them. This work presents the integration in standard Finite Element (FE) packages of a machine learning methodology that naturally captures the behaviour of composite materials: the multiscale method for periodic structures using domain decomposition and ECM-hyper reduction. The method provides a special type of finite element that can be assembled using FE libraries. However, the kinematics of this element may be described by more Degrees of Freedom (DoF) per node than most standard FE packages consider, hence implementing it is a non-trivial task. The strategy presented here tries to tackle the limitation by means of static condensation followed by a regression procedure. Periodic boundary conditions are employed for the extra DoFs while the regression consists in a polynomial on the logarithmic space. This paper focuses on the performance of the integrated beam element through the analysis of a pultruded omega profile whose anisotropy requires the use of complex models to accurately capture its mechanical behaviour. The agreement between the results obtained with the proposed model and those given by more complex formulations validates the methodology and enables its use in regular FE codes to characterize complex composite beam structures.

Additive preforming technology applied to carbon-reinforced composites

Enrique Hernández Murillo — Tue, 16 May 2023 16:33:03 +0200

Manufacturing composite materials by conventional methods is known to be costly as it requires many steps, equipment and tooling. The challenge this presents can benefit from the moldless approach and rapid, automated prototyping enabled by additive manufacturing. Today, additive technologies are changing the manufacturing processes of plastics and composites, allowing short series to be automated and scalable for adaptation to long series, always oriented to final part production. In addition, the mechanical limitations presented by 3D printing processes of polymeric materials have been enhanced by the reinforcement of short or continuous carbon and glass fibers, mainly. Moreover, the hybridization of additive technologies with conventional processes makes it possible to overcome their current limitations, taking advantage of many of their benefits and increasing the fields of application.

In this context, the idea of developing a technology that allows obtaining intermediate parts or preforms with high geometric complexity, which require a subsequent process, such as resin transfer molding (RTM), that confers mechanical performance similar to that of composites. In this work, an alternative method of manufacturing carbon fiber reinforced preforms using an additive process based on Fused Fusion Deposition Modeling (FDM) is detailed, as well as the production of composites from these preforms. Thus, the 3D preform is manufactured from fiber filaments coated with a thermoplastic binder. Then, this preform is subjected to a thermosetting resin injection process in a mold to obtain the final composite. In summary, a new method of additive preforming in combined with RTM is proposed to manufacture carbon fiber reinforced polymer composites (CFRPC).

Eco-design of lightweight structural parts for electric vehicles – ALMA project

Denise García — Tue, 16 May 2023 09:59:04 +0200

A great deal of work on lightweight cost-effective strategies has been underway in the last decades to improve the electric vehicle efficiency and driving range. At the time, and according to recent EU project results, up to 30-40% weight reduction was achieved so far in the vehicle structure at prototype level, but further efforts need to be invested to push the technology up to the market. Besides, the adoption of circular economy principles across the entire life-cycle is needed to enable, on one hand, the integration of environmental and cost considerations at the early design stages and, on the other hand, new options for the end-of-life recovery, repair, reuse and recycling.

ALMA project aims to apply eco-design principles to redefine the vehicle architecture and develop a new 26% lighter multi-material body structure using novel advanced high strength steel grades, high performance composites and advanced steel-hybrid laminates. Specifically, Designing for Assembly and Disassembly (DFA/DFD) and Design for Recycling (DFR) methodologies have been targeted to ensure cost-efficient separation, recycling and recovery at the end-of-life (EoL). The ALMA project has also considered aspects for the selection of the best material and production process for the right application at the design stage. The integration of regulatory considerations from early stages of design, especially forthcoming legislative requirements on emissions and the forthcoming ELV directive was also part of the design process.

As a result, the ALMA project intends to foster the adoption of a circular approach in the automotive sector, reinforced by the use of eco-design methodologies from early stages of the car conception and supported by LCA methodologies, helping the automotive industry to harmonize with circular economy principles: design to reduce the production of waste and pollution and extend life cycle for materials and products.

Development of manufacturing processes of hybrid structures made of recycled thermoplastic material with unidirectional inserts

Amaia de la Calle — Mon, 15 May 2023 10:44:03 +0200

One of the most important challenges in the automotive field is to deal with the new regulations regarding the material’s recycling, following the guidelines of the Circular Economy, without losing properties. The hybridization of parts of recycled material combined with continuous fiber inserts could be a solution to this problem. Within the framework of the ZeKonp project, a study and optimization of the manufacturing process variables of compression moulding of hybrid structures with unidirectional tape inserts. has been carried out

The starting material has been a plate of a semi-finished hybrid of GMT material obtained by scraps of UD tape from production waste. The reinforcement has been placed with a Multilayer automatic taping equipment.

In order to optimize the process, variables such as the arrangement of the material, temperature and compaction pressure, the strategy and speed of deposition of the strips and the welding process of the materials have been studied.

In addition to the reuse of the materials, the process and life cycles of the final product has also been taken into account in order to reduce the environmental impact throughout its life cycle

Nuevo concepto de eco-composite híbrido de fibra natural y láminas de madera (FWL). Fabricación, caracterización mecánica y envejecimiento en agua de mar. New concept of natural fibre-wood hybrid eco-composite (FWL). Manufacturing, mechanical characterization and seawater ageing.

Alberto Lopez-Arraiza — Sun, 14 May 2023 11:03:03 +0200

RESUMEN

En el presente trabajo se estudia un nuevo eco-composite tipo FWL (“Fiber-Wood Laminate”) obtenido mediante la hibridación de fibras naturales y láminas de madera. Para ello, se han fabricado laminados por infusión de bioepoxi (SuperSap®) reforzada con tres capas de fibra de lino bidireccional y dos chapas de madera de pino, una en cada cara del eco-composite. Posteriormente, se realizaron ensayos de tracción, impacto de baja energía (E₀=1J-25J) y se inspeccionó el daño mediante ultrasonidos. Igualmente, se repitió la caracterización para laminados sumergidos un periodo de bioactividad marina de 6 meses.

Los resultados muestran que el FWL presenta un aumento del módulo elástico del 58% frente al biocomposite de lino (FFRB). Tras la inmersión en agua de mar, se observa que la absorción de humedad provoca una caída de la rigidez del 4,6% y del 6,9% en el FWL y FFRB, respectivamente.

Por otro lado, los umbrales de penetración y perforación del FWL son un 29% y 32% inferiores a los correspondientes del FFRB. Después de la inmersión, dichos umbrales se desplazan a valores superiores en ambos eco-composites, más significativamente en el FFRB, debido al efecto plastificante de la absorción de humedad que se pone de manifiesto en los distintos patrones de daño observados por inspección mediante ultrasonidos.

En conclusión, las láminas de madera del FWL aumentan la rigidez a tracción del nuevo eco-composite y ejercen un efecto barrera frente a la absorción de humedad debido a la inclusión de la bio-resina en la estructura celular de la madera.

ABSTRACT

The present work explores a new concept of eco-composite named FWL (“Fiber-Wood Laminate”) obtained by combining natural fibres and wood sheets. The studied FWL configuration consisted of a single thin pinewood veneer at each of the outer layers of a bidirectional flax fibre-reinforced bio-epoxy (SuperSap®) manufactured by infusion. Tensile and low energy impact (E0=1J-25J) tests were performed and the damage was analysed by ultrasonic inspection. Furthermore, the last characterization was also conducted on laminates after being immersed during a marine bioactivity period of 6 months.

The results showed an increase in the Modulus of Elasticity by 58% in the FWL compared to the flax-reinforced biocomposite (FFRB). After seawater immersion, the stiffness decreased by 4.6% and 6.9% in the FWL and FFRB, respectively. The penetration and perforation energy thresholds of the FWL obtained by falling weight impact tests were 29 and 32% lower than those of the FFRB, respectively. The effect of seawater immersing entailed a displacement to higher values of the energy thresholds, mainly in those of the FFRB. The plasticizing result of moisture absorption was evident in the different damage patterns observed by ultrasonic inspection.

In conclusion, the thin pinewood veneers increased the tensile strength of the new eco-composite. The epoxy matrix filled the cellular structure of the wood, which acted as a barrier to reduce the water absorbed by the flax fibres.

NEW SUSTAINABLE BIO-PUR FORMULATIONS FOR OFFSHORE RENEWABLE ENERGY

Oihane Echeverria Altuna — Wed, 10 May 2023 14:54:12 +0200

The development of sustainable composites has become in a major strategy for different sectors, such as the offshore renewable energy industry.

Thermoset polyurethanes (PUR) offer some advantages for their use in structural composite parts, like their good thermal properties, adhesion with different types of fibers, ultra-fast curing, low viscosity and corrosion resistance, highlighting their resistance to fatigue and consequent durability. However, PUR have some environmental drawbacks, such as their petrochemical origin and low recyclability.

Consequently, biobased PUR (BIO-PUR) formulated based on polyols derived from vegetable oils have aroused keen interest. Moreover, it is possible to incorporate recycled monomers in their formulation, which are obtained from highly degraded plastics collected from the sea.

In addition, it is necessary to consider the PUR end of life to improve the composite sustainability. An interesting solution is the incorporation of dynamic bonds into the PUR network, with reversible capacity such as Diels-Alder, to improve the polymer recyclability.

Therefore, this work has focused on the development of a new formulation of BIO-PUR with the required mechanical properties for structural applications in the marine environment. In addition, the integration of recycled monomers and DA bonds have been explored to improve the circularity of the developed resin. To this end, aspects ranging from analysis and synthesis to the characterization of the resins have been covered.

Structural, optical and electrical properties of semiconductor films TiO2: Mn for solar cells

Begoña Asenjo — Mon, 03 Apr 2023 12:14:05 +0200

TiO2 is a semiconductor oxide with many applications due to its properties. To increase the electron transport of the material, it is usually doped with transition metal ions so as not to alter its chemical and mechanical stability and thus be able to use this material for the manufacture of solar cells. In this work, the effect of the incorporation of the Mn dopant on the optical and electrical structures of the TiO2 fims grown by chemical methods under different conditions and deposited by the spin coating technique on glass substrates. Using optical spectroscopy, the influence of the starting precursor, thickness of the fims and the concentration of the dopant was mainly observed with respect to transmittance.

Evaluation of conventional behavior of bitumen containing PET plastic and HMA pavement response utilizing 3D-Move analysis software

Nahusenay Muluken Tessera — Thu, 02 Mar 2023 16:32:48 +0100

A well-developed road network provides good services for road consumers. Most roads in the world are flexible types of pavement. Bitumen has viscous-elastic properties and is very sensitive to temperature; it plays a vital role in producing hot mix asphalt and influences the performance of HMA pavement. Flexible pavements are linked to extreme temperatures, causing rutting and fatigue cracking. Pavement distress shortens service life and increases maintenance costs. This research focused on improving pavement resistance to distress by modifying the conventional properties of bitumen using alternative materials such as shredded PET plastic. In this study, two stages were applied. The first stage was collecting samples, and the second stage determined the conventional properties of bitumen by adding 3%, 6%, and 9% of shredded PET plastic to the bitumen. Penetration, ductility, and softening point tests were performed to analyze the conventional behavior of bitumen. Finally, top-down and bottom-up cracks are used to evaluate rutting damage, with 3D-Move analysis software that accounts for moving vehicles under various loads and speeds. From the conventional bitumen test, at 3% PET plastic added to the bitumen has no significant effect on the penetration grade, Ductility, and softening point. However, when 6% and 9% PET by weight of bitumen mixed, the penetration grade, ductility, and softening result become 49.3mm, 45.5mm, 97mm, 85mm, and 57mm and 62^oC, respectively compared with the penetration grade, ductility, and softening point value of unmodified bitumen (66.5mm, 142cm, and 48.9^oC). Besides, the 3D-Move Analysis software results show that asphalt binders with higher PET plastic content best resist the rutting damage, top-down, and bottom cracks.

Robotic additive manufacturing of continuous carbon fiber thermoplastic composites

Alberto Pedreira — Mon, 27 Jun 2022 00:30:05 +0200

Fused Filament Fabrication (FFF) technology is one of the most popular 3D printing processes and interest in direct manufacturing of functional parts is growing. For this reason, both techniques and feedstock materials require improvements to meet the mechanical requirements of load-bearing components. In this sense, this work is focused on the robotized FFF process of continuous carbon fiber thermoplastic composites. It includes an analysis and comparison of the developed FFF robotic 3D printing process with the conventional process, as well as the development of robotic 3D printing equipment for the manufacture of continuous fiber reinforced composites and the characterization of the printing process developed to print the new filaments based on the thermoplastic matrix and reinforced with continuous carbon fiber. The material was analysed by microscopic analysis, and the manufacturing specimens were characterized by mechanical tensile and flexural tests.

Machining of Hybrid Composite Materials

Materiales Compuestos — Mon, 02 May 2022 16:38:49 +0200

Composite materials have been having an increasing importance in the industry. Their high specific properties and their high flexibility that allows tailoring materials that suit the needs of practically every project, have been leading to a growth in the demand of this kind of materials. Fiber-Metal Laminates have an established usage on the aeronautic industry and lately have been subject of research by the automotive industry.

Since composite manufacturing methods allow the obtention of components with their final geometry, drilling is the most used machining operation in the machining of composites. Drilling of composites is very demanding from the tools point of view, with very high wear rates and several defects can occur to the workpiece like delamination, fiber pull-outs, burrs and matrix degradation. When combined with a metal, additional challenges appear in drilling these materials such as loads of different magnitudes during a single operation and surface defects on the interface because of chip removal. Orbital drilling is seen as a promising alternative to conventional drilling, presenting several advantages that result in holes with higher quality.

Given the interest the automotive industry has been showing in fiber-metal laminates constituted by steel and carbon fiber reinforced plastics (CFRP) and due to the lack of information regarding drilling of this combination of materials, the aim of this work was to evaluate the influence of the machining parameters in the quality of holes obtained by orbital drilling. A full factorial design of experiments was done and the influence of the parameters was then evaluated by means of an Analysis of Variance (ANOVA).