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Documents published in Scipedia

• Hybrid laser joining of thermoplastic composites with stainless steel

  B. Cárcel, S. Sayas, S. López, R. Emmerich, P. Gerard, R. Ruiz

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 113

  
  

  Abstract

  There is an increasing interest in the use of multi-materials in the transport sector in order to reduce the weight of vehicles and the  fuel consumption for a clean mobility towards the goal of zero CO2 emissions, as defined the European directive (EU) 2019/1161. The use of hybrid materials has promoted the research on dissimilar joints (metal-polymer) in order to solve the drawbacks related to the traditional joining techniques such as stress concentration, large repairs area and emissions harmful to the environment. In this work, the behavior of hybrid joints between steel and GRFC with thermoplastic matrix by laser technology has been analyzed. This study is framed to the European project RECOTRANS, focused on the manufacturing of composites (RTM and pultrusion) with new MW accelerated curing acrylic resins and their joining to metal inserts using LAMP technology (laser assisted metal polymer joining). Laser technology for metal-polymer joining is an alternative to other conventional processes offering relevant advantages over these techniques since it is a single-stage instantaneous automated process, with localized heating and low residual stresses. In this study, the shear behavior of laser assisted joints between AISI304 steel samples and composites with different acrylic resin formulations has been analyzed. The effect that different variables have on these joints has been evaluated, such as the topography of the metallic surface, the temperature generated during the joining process or the laser interaction time. The results obtained show a mechanical resistance similar or even higher than that obtained in adhesive joining.    

  Abstract
  There is an increasing interest in the use of multi-materials in the transport sector in order to reduce the weight of vehicles and the  fuel consumption for a clean [...]

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• Thermomechanical characterization of biolaminates epoxy/sisal

  A. Castillo-García, P. González-García, E. Franco-Urquiza

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 132

  
  

  Abstract

  One of the most common materials to be used as cores of sandwich structures is polymeric foam. Due to an increasing effort to reduce the environmental impact of industrial processes, there is a great interest in the incorporation of natural materials from renewable sources to facilitate the reusing and recycling of the structures. One of the possibilities for replacing polymeric foams in sandwich structures is agglomerated cork, due to its good mechanical properties. However, for this material to be used as a core, it is necessary to know its behaviour under impact loads, both at low and high velocities. In this work, the behaviour of a commercial PVC foam is compared with agglomerated corks of several densities. The force, displacement, absorbed energy and perforation velocity have been analysed. The behaviour of the agglomerated cork can be similar to that of a conventional polymeric foam, although with an increase in weight. However, it has been shown that agglomerated cork can be a better alternative to polymeric foams in those applications that may be subjected to several successive impacts.

  Abstract
  One of the most common materials to be used as cores of sandwich structures is polymeric foam. Due to an increasing effort to reduce the environmental impact of industrial [...]

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• Optimización Instalación Térmica (vs) Sistema de Producción: Caso Práctico “Hot-forming"

  M. Rodríguez, C. C.Saleiro

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 157

  
  

  Abstract

  Productividad y reducción de costes, son actualmente dos de los principales “drivers” que motivan nuevas formas de parámetros de control en los procesos de fabricación de materiales compuestos. El sector aeronáutico no es propiamente conocido como de producción en masa, sin embargo, por la naturaleza y requisitos de autoridades certificadoras, requiere que todos los pasos del proceso estén controlados y documentados. Esto supone la ventaja de ser una fuente de generación de datos de control que analizados correctamente, creando las correlaciones pertinentes y con un objetivo claro pueden permitirnos establecer otras formas alternativas de control que cumplan con los requerimientos y nos conduzcan a un aumento de la productividad y ahorro de costes. Uno de los procesos de mejora es el de Hot-forming. Este es un proceso utilizado para proporcionar, a laminados de espesor considerable, una pre-forma antes del proceso de curado, garantizando una mejor calidad del conformado de detalles intrincados de pieza, que en caso de no realizarse producirían defectos no aceptables, como ejemplo, en zonas de radios. Después de varios años trabajando con plantas de fabricación de materiales compuestos, se han definido los parámetros claves del proceso en un medio industrial (medio de calentamiento, materiales auxiliares, construcción de piezas, parámetros de control, limitaciones de equipamiento y de material, posible envejecimiento de material). Esta es la base de la presentación sobre la cual se expondrá el método experimental seguido para justificar la correlación de datos de control del proceso de Hot-forming por membrana en vez de control en pieza.

  Abstract
  Productividad y reducción de costes, son actualmente dos de los principales “drivers” que motivan nuevas formas de parámetros de control en los procesos [...]

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• Vol4 num2-20 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. 2 - Procesos de Fabricación y Técnicas de Unión), 112

  
  

  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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• Adhesive Film Carriers Effect on Adhesive Function

  V. Capilla, C. C.Saleiro

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 110

  
  

  Abstract

  One of the main "drivers" in the development of aeronautical structures in composite material is the development of more integrated structures that are manufactured in a single step ("One-Shot") to optimize times. The adhesive materials in film format are one of the main variables to take into consideration to achieve the aforementioned integration. This need has promoted creativity at the level of use / parameterization of new adhesives in the form of a film. Film adhesives are used in the integration of composite, sandwich or monolithic structures. Regarding sandwich structures, the adhesive film is used to ensure a good adhesion between the core and the prepreg, through the formation of a meniscus of adhesive material in the core cell. This function is fulfilled depending on the type of "carrier". For Monolithic structures, the adhesive film is used to ensure a good adhesion in co-bonding processes (bonding of cured laminate with fresh prepreg) and secondary bonding (bonding between 2 previously cured laminates), interleaved between materials to achieve optimum thickness, guaranteeing the best mechanical properties of the element at interlaminar level. This, without forgetting, the repair processes that are within the processes of co-bonding, with all its specificities and operational limitations, either in manufacturing or in service. The market options, qualified by OEMs or not, are wide, having developed different support materials, or variants of the same material, with the aim of achieving the best mechanical properties of the elements where they are used.

  Abstract
  One of the main "drivers" in the development of aeronautical structures in composite material is the development of more integrated structures that are manufactured [...]

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• Influence of surface topography parameters on the structural adhesive of aluminum 7075 polishing by robot and TEPEX®

  J. .Martínez, M. Prado, M. Fenollera, J. Perez, A. Pereira

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 108

  
  

  Abstract

  In the process of continuous improvement of manufacturing processes in the field of the automotive sector comes this study developed within the framework of the Ecovoss project. Its objective is based on substitution of aluminum welding operations with the option of adhesive operations with other types of materials such as polyamides or, in this case, a TEPEX® composite material (dynalite 202-c200 / 50% TYP 13). In this work we try to test the best texturing in the union of 7075 aluminum specimens manufactured by robotized polishing with ABB 6640 robot, with specimens in TEPEX® material cutted in order to have a surface for application of the adhesive product. It uses a structural adhesive film AF-163-2 from 3M, which must be applied with determined pressure and temperature. The tests carried out are based on the topographic measurement of the surfaces to be adhesively bonded with the Alicona interferometer and in the tests for cutting the adhesive bond. The expected results must provide the state conditions of the surfaces to optimize the adhesiveness of the materials studied.

  Abstract
  In the process of continuous improvement of manufacturing processes in the field of the automotive sector comes this study developed within the framework of the Ecovoss project. [...]

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• CFRP advanced surface characterization prior to adhesive bonding. Peel ply treatment vs UV laser

  M. Botana, F. Serrano

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 106

  
  

  Abstract

  Surface treatment is one of the most important issues for obtaining high quality adhesive bonding. The main objective of this treatment is the removal of surface contaminants, the modification of surface roughness and the increase of surface free energy, without damaging the surface of the composite material. Nowadays, the treatments which are approved by the aeronautical sector for the surface preparation of CFRP prior to adhesive bonding are manual and some of them depend on the skills of the operator. Because of this, different automatable alternatives are being studied in order to substitute these traditional methods. One of these alternatives is the use of UV laser radiation. In this work the advanced surface characterization of CFRP surfaces treated with peel ply and processed with UV laser have been performed. Advanced techniques have been used in order to evaluate the changes that occur in the surface and which can be related to adhesiveness. Thus, techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), surface free energy determination and 3D optical confocal profilometry have been used to evaluate chemical and physical properties of treated surfaces. Obtained results show that UV laser radiation leads to surface changes which would improve the adhesiveness of the surfaces, although these changes suggest that the mechanism by which adhesion happens is different from the one which is related to peel ply.  

  Abstract
  Surface treatment is one of the most important issues for obtaining high quality adhesive bonding. The main objective of this treatment is the removal of surface contaminants, [...]

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• Machining of Hybrid Composite Materials

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

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 104

  
  

  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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• Estudio topográfico y dimensional de material poliuretano termoestable mecanizado mediante mecanizado robotizado

  M. Prado, A. Pereira, M. Fenollera, J. Martínez, . J.A.Pérez

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 103

  
  

  Abstract

  El poliuretano termoestable es un material utilizado en el sector de modelizado y actualmente está sustituyendo a piezas estructurales en maquetas de control del sector del automóvil y aeronáutico, por su facilidad de mecanizado, además de aportar unas buenas propiedades mecánicas.  En este trabajo se ha experimentado el mecanizado robotizado de un material poliuretano comercial tipo Necuron® 651. El mecanizado robotizado ofrece una amplia posibilidad de mecanizar y modelar materiales con la ventaja de aumentar la accesibilidad a las piezas, en comparación con los centros de mecanizado convencionales de tres o más ejes. El mecanizado se ha llevado a cabo con una instalación consistente en un robot ABB® 6640-235 con un cabezal de alta velocidad Peroni® y mesa rotativa ABB. La desventaja del mecanizado robotizado, causado por la falta de rigidez de la morfología del robot, son los errores macro y micro dimensionales. Se han realizado geometrías sencillas con herramientas enterizas de acero rápido. La programación CAM se ha obtenido con el software Powermill® de la compañía DELCAM, teniendo en cuenta dos tipos de estrategias de limitación de grados de libertad del robot, para verificar resultados geométricos. Finalmente se ha medido y analizado la superficie generada mediante interferómetro autofocus Alicona y se ha medido la macrogeometría de las muestras en máquina de medición por coordenadas. Los resultados muestran que los errores tanto micro como macro disminuyen significativamente si se hacen fijos alguno de los siete ejes, del sistema robotizado.

  Abstract
  El poliuretano termoestable es un material utilizado en el sector de modelizado y actualmente está sustituyendo a piezas estructurales en maquetas de control del sector [...]

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• Automatic 3D cutting of dry CFRP preforms based on computer vision

  A. Guillen, J. Peña, F. Domínguez, A. Calero, S. Delgado

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 2 - Procesos de Fabricación y Técnicas de Unión), 102

  
  

  Abstract

  Cutting preforms in complex 3D geometries  is one of the challeges of carbon fiber manufacturing for both prepreg and dry fibre parts. Even after cutting layer by layer, a subsequent process is still necessary  due to possitioning tolerances and the need of trimming of the edges. Nowadays, this process is carried out by hand. These manual cuts are performed on cutting mats and employ specific tooling to keep the preform in a fixed position and shape. Moreover, often it is necessary to move the preform into several cutting positions leading to poor ergonomics, specially for very thick preforms. The process presented here attempts to solve this problem by introducing an automatic cut without any cutting mat nor complex and expensive fixing jig. The greatest difficulty of this approach lies on the flexibility of the preforms as they are not rigid enough to maintain their shape and position during the cut. The solution combines a computer vision system  withan ultrasound cutting system embedded on a robotic arm. This may lead to improvements in productivity as well as in quality (Regarding cut tolerances and finish) as well as increased repeatability compared to manual processes, enabling the deveolpment of net preform cutting technologies. Templates are not required and tooling is simpler, so recurring costs plummet as well as set up times. This is specially useful for prototyping and short production series as cutting lines may be easily modified without making new templates since  the system is able to identify the new cutting path.

  Abstract
  Cutting preforms in complex 3D geometries  is one of the challeges of carbon fiber manufacturing for both prepreg and dry fibre parts. Even after cutting layer by layer, [...]

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