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• Design and optimization of a self-deployable composite structure

  P. Fernandes, R. Marques, R. Pinto, P. Mimoso, J. Rodrigues, A. Silva, J. Tavares, G. Rodrigues, N. Correia

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 69

  
  

  Abstract

  Self-deployable composite structures are attractive for space applications as they provide lightweight, low cost and simple solutions that can replace mechanical systems. These structures can be folded and use the stored strain energy to promote a self-deployment event. However, these structures present design, manufacture and optimize challenges. This article describes the process of designing and optimizing an elastic-hinge, for a telecommunication satellite considering both structural and frequency requirements using finite element analysis, manufacturing and experimental testing. Furthermore, the paper details the sequence of optimization algorithms that were used to produce a solution capable of meeting the original design specifications. The structural assessment consists of the elastic-hinge numerical modelling during the folding process, by means of an explicit formulation. This model correlates well to the experimental test data and was used to evaluate the damage installed in the hinge using a pletfora of damage criteria. The frequency analysis considers the numerical modelling of a system constituted by the elastic-hinge and a telecommunication satellite antenna. This model was used to estimate the natural frequency of the system. Results show that a design methodology which uses a genetic algorithm (GA) for a global search, followed by a particle swarm optimization (PSO) method for a local search provides a good approach to the optimization problem. It is also shown that the efficiency of these algorithms can be maximized by tailoring their architecture and internal parameters.

  Abstract
  Self-deployable composite structures are attractive for space applications as they provide lightweight, low cost and simple solutions that can replace mechanical systems. [...]

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• 3D-printing self-healing composite polymer reinforced with carbon nanotubes

  R. Calderón-Villajos, A. López, L. Peponi, J. Manzano-Santamaría, A. Ureña

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 70

  
  

  Abstract

  EMAA copolymer neutralized with sodium salt is a type of ionomer with self-healing abilities. This polymer has been used as raw material for the manufacturing of nanocomposite material by the addition of multiwall carbon nanotubes (MWCNTs). The optimization of the extrusion process, as well as the mixing and dispersion of the nano-reinforcement in the polymeric matrix during extrusion, deals with the manufacturing of a homogeneous reinforced filament. The obtained filaments were used afterwards as feeding materials of a 3D polymer printing machine and tensile test samples were manufactured. Mechanical properties of both unreinforced and reinforced samples were tested. The MWCNTs-reinforced samples exhibited higher mechanical properties without affecting its self-healing ability.

  Abstract
  EMAA copolymer neutralized with sodium salt is a type of ionomer with self-healing abilities. This polymer has been used as raw material for the manufacturing of nanocomposite [...]

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• Manufacturing and study of the properties of polymer matrix composites reinforced with magnetite and carbon black for electromagnetic shielding applications

  A. Posada, J. Barrado, D. Téllez, J. Roa-Rojas, . A.Rosales-Riveros, N. Salazar-Henao

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 72

  
  

  Abstract

  This work describes the production and morphological, structural, and magnetic characterization, as well as the electromagnetic shielding properties of polymeric based composites reinforced with different ratios of magnetite and carbon black. This kind of composites are used not only for the manufacture of electronic elements such as shape memory polymers, sensors and transducers, but especially for the production of electromagnetic shielding materials in both passive defense and civil construction applications; Buildings, vehicles or airplanes. The melt mixing method and vulcanization procees was followed for the manufacture of the composites.Composite materials with natural magnetite and synthetic magnetite have been considered separately. Reinforcements fillers were added in different ratios. The morphological analysis carried out by FESEM demonstrates the differences in size and shape of the fillers.Through the Raman and XPS spectroscopy the  interface matrix-fillers was studied. The magnetite content, as well as its source, directly affect the magnetic behavior of the composites. The electromagnetic shielding properties were evaluated in the X band of frequency (8-12 GHz) and K band (18-27 GHz), with attenuations greater than 34 dB for the composites with the highest amount of magnetite. 

  Abstract
  This work describes the production and morphological, structural, and magnetic characterization, as well as the electromagnetic shielding properties of polymeric based composites [...]

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• Development of new high performance PUR resin formulations for processes of high production rate of structural components

  O. Echeverria-Altuna, O. Ollo, I. Harismendy, A. Eceiza

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 75

  
  

  Abstract

  The deployment of composites for lightweight solutions in the automotive market is still emerging due to the production cost of these components and the limited production capacity of current manufacturing technologies. The development of more reactive formulations for processes that allow to increase production rates and reduce process times to a few minutes are arousing great interest, such as the HP-RTM (high pressure RTM) and the HP-CRTM (RTM compression). In the case of RTM resins, ultra-fast (2-5min) and low viscosity curing formulations are sought to optimize the curing and injection cycles to the maximum. The technology based on polyurethane resins (PUR) offers against other alternatives the advantage of having great tenacity and resistance to fatigue which makes it especially attractive for elements subject to impacts or cyclic loads such as suspension elements. This work, based on simulations, has determined an optimal value of the PUR viscosity for RTM. In addition, a preliminary analysis of the curing kinetics of a commercial PUR resin has been carried out. The results indicate that the resin evaluated is not viable for the process due to its high reactivity at the beginning of curing, so that work will continue on the search for more latent PUR solutions for RTM.

  Abstract
  The deployment of composites for lightweight solutions in the automotive market is still emerging due to the production cost of these components and the limited production [...]

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• Manufacturing and mechanical characterization of natural fibre reinforced biocomposites. Application in a small wind turbine

  J. Vallori, G. Vargas, A. Boyano, A. Lopez-Arraiza

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 76

  
  

  Abstract

  In this work, new biocomposites were manufactured and mechanically tested. A resin from natural resources (SuperSap®) was reinforced by a bidirectional flax and oak wood laminates. Normalized tensile and three-point bending tests were performed and it was observed that the oak wood laminates in the outer layers give a great aesthetic finish and the tensile stiffness is also increased a 2% compared to the flax reinforced biocomposite. Regarding the results of three-point bending, the oak laminates in the core provide a greater flexure breaking strength, which is a 10% higher than the flax reinforced biocomposite. SEM micrographs show both the accuracy of the infusion process and the good adhesion of the different natural fibres and bioresin. Finite Element simulations (FEM) were carried out at different pressures generated by three wind velocities (Vwind= 3, 8 and 11m/s). Both tension and deformation results show that the structural integrity of the biocomposite wind blades is not compromised. Finally, the real tests in the wind tunnel have validated the use of the developed biomaterials in manufacturing blades for small wind turbines.

  Abstract
  In this work, new biocomposites were manufactured and mechanically tested. A resin from natural resources (SuperSap®) was reinforced by a bidirectional flax and oak wood [...]

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• Monitoring of multi-material structures for offshore applications with fiber optic sensors

  T. Grandal, D. Pérez, S. Dasilva, R. Mano, S. Fraga, L. Mera, E. Rodriguez

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 1 - Avances en Materiales Compuestos. Nuevos Campos de Aplicación.), 78

  
  

  Abstract

  The development of renewable energies is a fundamental need to meet the ambitious energy targets demanded by industry and the European Union in the coming years. In the case of offshore wind energy, it has certain limitations due to its relative youth and associated costs, especially in the maintenance, operation and repair operations. Within the project, that includes this work, has developed a new multi-material component with high structural requirements for the offshore wind sector. A combination of steel and composite, manufactured by filament winding, with a system of protection of biofouling and corrosion, will be validated in a real conditions test in the experimental zone of INEGA (A Coruña), by a demonstrator to scale 1:5. For real-time monitoring of the multi-material structure, a monitoring system has been developed based on fiber optics sensors type Bragg Grating (FBG), integrated in this structure. This monitoring system includes sensors of corrosion, temperature and deformation. This paper shows the development and characterization of these sensors at the laboratory level against mechanical, thermal tests and study durability in marine environment. In addition, it describes the integration of the monitoring system in the demonstrator and its response during the validation phase.

  Abstract
  The development of renewable energies is a fundamental need to meet the ambitious energy targets demanded by industry and the European Union in the coming years. In the case [...]

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• Machining of Hybrid Composite Materials

  M. Rodriguez, M. Freitas, A. Marques, A. Jesus, S. Villa

  Materiales Compuestos (Online first).

  
  

  Abstract

  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).

  Abstract
  Composite materials have been having an increasing importance in the industry. Their high specific properties and their high flexibility that allows tailoring materials that [...]

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• Optimization of direct dissimilar joining metal – thermoplastic composite for automotive and aerospace applications

  L. Blanco, P. Rey, A. Pedreira, M. Coto

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 109

  
  

  Abstract

  The transport industry is dominated by the challenge on lightening the weight due to environmental restrictions and cost reduction. The use of different materials and multi-material designs provide a great opportunity to develop products capable of meeting this challenge. Critical aspects to be considered in multi-material manufacturing are surface preparation and dissimilar joining. The multi-material joining metal-composite thermoplastic (CTP) is critical for different aspects such as low adhesion due to a low chemical affinity or corrosion problems in the case of the use of carbon fiber reinforced composites. On the other hand, laser texturing is one of the most promising techniques to create surfaces with controlled roughness, manufacturing in a single step and improving metal-CTP adhesion, without the need to use adhesives. This work, developed within the framework of the European COMMUNION project (GA680567), addresses the optimization of the direct joining process between different high-performance metals and thermoplastic composite cintas. The study deals with surface preparation using laser texturing, the study of different joining strategies and the characterization of joints using different techniques and Single-Lap Shear tests. Depending on the texture, type of materials or manufacturing strategy, the strength of the joint is improved by 50-200%, achieving structural strength values (> 10MPa) in the optimized joints.

  Abstract
  The transport industry is dominated by the challenge on lightening the weight due to environmental restrictions and cost reduction. The use of different materials and multi-material [...]

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• Use of biogenic silica nanoparticles derived from biomass in polymeric formulations and their applications

  H. Aguilar, D. Conceição, A. Barros, V. Bouça, M. Ornelas, R. Malgueiro, A. Carvalho, A. Portela, C. Silva, E. Döpelheuer, S. Grishchuk, L. Gryshchuk, M. Gilberg, B. Wetzel

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 128

  
  

  Abstract

  In view of moving towards a post-petroleum society, several attempts are being made to reconcile resource scarcity and environmental objectives with the use of biomass for multisector industrial applications. ReInvent project aims to deliver novel bio-based materials as additives/bio-nanofillers for insulation and structural products used in buildings and lightweight soft foams for vehicle interior products. The extraction/fractionation processes from biorefineries aim to provide sustainable raw-materials for the development of functional bio-nanosilica particles to be incorporated in polymeric matrices, to produce new advanced cellular and composite materials. Particularly, this work lies on the extraction, purification and characterization of bio-nanosilica extracted from rich-silicate residues (e.g. rice husks, hempshells, hempfibres, oil pressing solid residues). The extracts were examined using scanning electron microscopy, and their textural properties were evaluated by surface area and pore measurements. Influence of bio-nanosilica on the rheological behaviours of biobased furan and greened indirect polyurea resins was studied in terms of possible prepregging of both resins. A comparison of influence of bio-nanosilica dispersed in isocyanate and waterglass (WG) components on the chemo-rheological behaviour of the resin was performed, showing a strong increase of viscosity at ambient conditions, but no obvious difference at typical processing temperatures between 60‑90 °C.Thus, similar processing conditions, improved handling and storage ability of related prepregs were ensured. Obvious reduction of reaction speed, confirmed by slower increase of viscosity, was characteristic for IPU resin containing bio-nanosilica particles, especially when dispersed in WG, potentiating longer shelf-life of such highly reactive prepregs at cold storage conditions.

  Abstract
  In view of moving towards a post-petroleum society, several attempts are being made to reconcile resource scarcity and environmental objectives with the use of biomass for [...]

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• Bioinspired hybrid materials for reduction of viscous drag in ships

  A. Rodríguez-Ortiz, J. Suárez-Bermejo, P. Pinilla-Cea

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 117

  
  

  Abstract

  Nature has evolved structural materials along millions of years of incremental changes to fulfil functional requirements of very different situations. Let´s take as an example the sharks, one of the best adapted species for swimming across the oceans, and their smooth skin that is composed of millions of small scales (denticles), with complex geometries formed by sharp spines and micro-grooves aligned with flow direction, varying in size and shape at different locations of the sharkskin. The purpose of this microstructure is to reduce the viscous drag produced by the water when it adheres to the hull forming the fluid boundary layer, which can stick out the added mass to the weight of the fish and increase dramatically its peak speed. Inspired by this natural solution, we have started the design of a bioinspired new material, to be incorporated to the hull wet surface, reducing the viscous drag and increasing the velocity and the efficiency (less fuel consumption) of the ship. In this way, it will be easier to control the green effect gas emissions while sailing. We present the development of this new bioinspired, hybrid material with scales obtained by additive manufacturing using polymeric materials. To control the orientation of the denticles respect to flow direction, the scales have been mounted on a substrate of hydrogel, who interact with the fluid field of pressures to adapt the angle of the moving scales as the velocity increases. No mechanical devices are needed, as the hydrogel act as a nonlinear spring accommodating the movements of the scales. CFD code helps in the development of the most efficient shape and coating design. A water channel has been developed to measure the actual forces acting on the surface of coated panels.

  Abstract
  Nature has evolved structural materials along millions of years of incremental changes to fulfil functional requirements of very different situations. Let´s take as [...]

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