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Giorgini L.,University of Bologna | Benelli T.,University of Bologna | Mazzocchetti L.,University of Bologna | Leonardi C.,University of Bologna | And 7 more authors.
Polymer Composites | Year: 2015

Cured and uncured scraps from manufacturing of epoxy based carbon fiber reinforced composites were treated with a pyrolytic process to provide, as solid residue, carbon fibers to be re-used in new composites production. The industrial scraps were pyrolyzed at different temperatures in a 70 kg batch pilot plant and the pyrolysis products (gas, oil, and solid) were fully characterized. The solid residue (carbon fibers covered by a carbonaceous layer) was subjected to a further oxidative step at 500 and 600°C for different residence times to provide fibers devoid of any organic residue that did not volatilize during pyrolysis. The effects of both pyrolysis and oxidative process on the recovered fibers were evaluated by scanning electron microscopy and Raman Spectroscopy. The reinforcement behavior of pyrolyzed and pyrolyzed/oxidized chopped fibers, compared to virgin fibers, was tested in the production of new Chopped Carbon Fiber Reinforced Composites. The optimized double pyrolysis/oxidation process was found to provide fibers whose performance in the composites were comparable to the virgin ones. © 2015 Society of Plastics Engineers.


Giorgini L.,University of Bologna | Benelli T.,University of Bologna | Mazzocchetti L.,University of Bologna | Leonardi C.,University of Bologna | And 5 more authors.
AIP Conference Proceedings | Year: 2014

Pyrolysis is shown to be an efficient method for recycling carbon fiber composites in the form of both uncured prepregs scraps or as cured end-of-life objects. The pyrolytic process leads to different products in three physical states of matter. The gaseous fraction, called syngas, can be used as energy feedstock in the process itself. The oil fraction can be used as fuel or chemical feedstock. The solid residue contains substantially unharmed carbon fibers that can be isolated and recovered for the production of new composite materials, thus closing the life cycle of the composite in a "cradle to cradle" approach. All the pyrolysis outputs were thoroughly analyzed and characterized in terms of composition for oil and gas fraction and surface characteristics of the fibers. In particular, it is of paramount importance to correlate the aspect and properties of the fibers obtained with different composite feedstock and operational conditions, that can be significantly different, with the reinforcing performance in the newly produced Recycled Carbon Fibers Reinforced Polymers. Present results have been obtained on a pyrolysis pilot plant that offers the possibility of treating up to 70kg of materials, thus leading to a significant amount of products to be tested in the further composites production, focused mainly on chopped carbon fiber reinforcement. © 2014 AIP Publishing LLC.


Scafe M.,ENEA | Raiteri G.,ENEA | Brentari A.,Certimac s.c.a.r.l | Dlacic R.,Scuderia Toro Rosso s.p.a. | And 3 more authors.
Frattura ed Integrita Strutturale | Year: 2014

In this work has been estimated the compressive strength of a unidirectional lamina of a carbon/epoxy composite material, using the cross-ply and angle-ply laminates. Over the years various methods have been developed to deduce compressive properties of composite materials reinforced with long fibres. Each of these methods is characterized by a specific way of applying load to the specimen. The method chosen to perform the compression tests is the Wyoming Combined Loading Compression (CLC) Test Method, described in ASTM D 6641/D 6641M-09. This method presents many advantages, especially: the load application on the specimen (end load combined with shear load), the reproducibility of measurements and the experimental equipment quite simplified. Six different laminates were tested in compressive tests. They were realized by the same unidirectional prepreg, but with different stacking sequences: two cross-ply [0/90]ns, two angle-ply [0/90/±45]ns and two unidirectional laminates [0]ns and [90]ns. The estimate of the compressive strength of the unidirectional laminates at 0°, was done by an indirect analytical method, developed from the classical lamination theory, and which uses a multiplicative parameter known as Back-out Factor (BF). The BF is determined by using the experimental values obtained from compression tests. Finally, extrapolated data were compared with prepreg manufacturer datasheet.


Giorgini L.,University of Bologna | Mazzocchetti L.,University of Bologna | Benelli T.,University of Bologna | Minak G.,University of Bologna | And 3 more authors.
Polymer Composites | Year: 2013

The industrial production of a thick part obtained by hand lay-up of two commercial prepregs (≈35 mm) and intended for primary structural application is considered. Prepregs are made of either unidirectionally aligned fibers, PP-UD, or 2 × 2 twill woven fabric, PP-T2. While the resin is exactly the same, the prepreg production technology is different, namely, hot melt and solvent impregnation, respectively. The study shows that the prepregs age differently in the time span required for the process work up. Moreover, simulation of the independent curing process of each raw material shows unexpected differences both in the timescale (PP-UD reacts faster than PP-T2) and in the extent of reaction (PP-UD develops a higher amount of heat than PP-T2). The outlined differences require a particular care in the design of the curing cycle for production of thick composites where sequences of different prepregs alternate with no necessarily regular pattern, in order to reduce overheating, and to promote equal reaction of the two components without inducing too much residual stress between adjacent layers. This work shows that the experimental verification of raw materials and curing conditions might help identifying unforeseen industrial critical situations and avoiding the lack of performance in the final composite materials. © 2013 Society of Plastics Engineers.


Poodts E.,University of Bologna | Poodts E.,University of Buenos Aires | Minak G.,University of Bologna | Dolcini E.,RI BA COMPOSITES Srl | Donati L.,University of Bologna
Composites Part B: Engineering | Year: 2013

Vacuum assisted resin infusion process (VARI) is a high performance and cost effective manufacturing technology usually applied to produce large structures made of composite materials. In the industrial practice, trial and error approach is usually applied for the definition of injection locations and strategies during VARI processing thus generating a high risk of failure during the early stages of production of a new component. The present article deals with the development and validation of the FE analysis by means of the PAM-RTM code of a ship runway through the definition of a standardized experiment for the characterization of the laminates to obtain reliable permeability data. Indeed the assessment of laminate permeability proprieties (K) during the process is the major concern for reliable FE application: a procedure to obtain these characteristic values with few experimental tests is presented starting initially with a classic characterization at constant fibre volume fraction (Vf) and then extending the approach for the construction of a Pressure-Vf dependant curves. The tests were realized with carbon fibres fabrics, epoxy for infusion resin and PVC perforated core. Moreover the article provides an innovative approach for the computation of sandwich structures when perforated cores are used: the obtained data are finally applied with success for the validation of the simulation of the production phases of the ship runway characterized by the sandwich structure. © 2013 Elsevier Ltd. All rights reserved.


Lazzarini A.,Ferrari | Valgimigli A.,Ferrari | Baldini A.,Ferrari | Dolcini E.,RiBa Composites S.r.l. | Sangermano S.,Maserati S.p.A.
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2013

The current emissions regulations lead car manufacturers to look carefully for weight reduction. In the automotive industry the classic trial-and-error approach to design is becoming inadequate and techniques based on optimization are necessary to improve the design process. In this study a methodology to design a sport-car front hood is proposed. The process carried out could also be extended to car components characterised by a similar configuration. Starting from the geometry of the actual part, a design volume has been defined. The first step consists of a topology optimization performed considering the material as isotropic (aluminium properties): The output is a rough structure which accomplishes all the imposed targets. The interpretation of the topology results brings to a re-design phase aimed at realising a feasible component. The subsequent optimization step is dedicated to composite material structures and acts on the component plybook, varying thickness and orientation of each ply to find the best solution complying with targets. Finally, the component has to be reviewed from a technological point of view in order to be virtually delivered and to proceed with the prototype phase. Copyright © 2013 by ASME.


Miscia G.,University of Modena and Reggio Emilia | Bertocchi E.,University of Modena and Reggio Emilia | D'Agostino L.,University of Modena and Reggio Emilia | Baldini A.,University of Modena and Reggio Emilia | And 2 more authors.
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2013

In the last few years, the restrictive safety standards and the need for weight reduction have brought the crashworthiness research to focus on composite materials because of their high energy absortion-to-mass ratio. On the other hand, the possibility of obtaining predictive dynamic FEA models for these new materials is still an open issue: The present work aims at developing a methodology for the characterization of composite materials with particular interest for the head impact simulation. Composite materials behavior, defined through the mathematical models implemented in FEA codes, is very complex and requires a large amount of physical and numerical setting parameters. The majority of these parameters can be obtained by an experimental campaign that involves several kind of different tests. The presented methodology allows to obtain a good numerical-experimental correlation simply performing few tests which emulate the behavior of the component during the head impact event. A software tool based on a genetic optimization technique has been developed in order to determinate automatically the material properties values that guarantee the best numericalexperimental correlation. Copyright copy; 2013 by ASME.


Camattari R.,University of Ferrara | Dolcini E.,RI BA Composites Srl | Bellucci V.,University of Ferrara | Mazzolari A.,University of Ferrara | Guidi V.,University of Ferrara
Journal of Applied Crystallography | Year: 2014

The diffraction capability of two crystalline silicon plates bent by carbon fiber deposition has been studied. The performed treatment induced a permanent curvature in the samples, resulting in an increase of the diffraction efficiency. The obtained efficiencies are constant over a wide angular range and close to the theoretical expectations, meaning that the curvatures were homogeneous. Most importantly, the bending technique allowed the manufacture of bent samples up to 5 mm thick and with a radius of curvature down to 30 m. With such a technique, the fabrication of crystals for the realization of a hard X-ray concentrator (Laue lens) for astrophysical purposes is enabled. © 2014 International Union of Crystallography.


Giorgini L.,University of Bologna | Mazzocchetti L.,University of Bologna | Minak G.,University of Bologna | Dolcini E.,RI BA COMPOSITES Srl
AIP Conference Proceedings | Year: 2012

A case-study is presented, in cooperation with RI-BA Composites srl, where the industrial production of a thick part for primary structural application is analysed. The final product is a bulk carbon fiber reinforced object characterized by great dimensions, with thickness ranging between 10mm and 35mm and obtained by Hand-Lay-Up of prepregs. The study shows that prepregs age along the time required for the process work up. Moreover, the isothermal curing investigation of the prepreg used in the production gives some useful hint for the design of a new thermal curing cycle, in order to avoid exotherm problems along the thickness of the object. The effect of the applied curing cycle on thermal properties of the object are reported. © 2012 American Institute of Physics.


Grant
Agency: European Commission | Branch: H2020 | Program: IA | Phase: FTIPilot-1-2015 | Award Amount: 2.44M | Year: 2016

The aim of CARIM is the final development, homologation and commercialization of a full carbon automotive wheel manufactured in an automated, high-volume production process. Within the 2-year project the TRL level, currently 6\, will be raised to 8\ or 9. Developments in automated CFRP production technology will generate a wheel that is 30-50% lighter than state-of-the-art Al-wheels, with the extra advantage of excellent mechanical performance. The manufacture of the wheels in an automated preforming and HP-RTM process will ensure short cycle times (max. 10 min/component) and lower costs (1634/wheel in first year of production and 1164 in 2020) that will enable scale-up to series production and make the CARIM wheels competitive against current casted and forged Al-wheels and other emerging plastic wheel concepts. A testing and validation phase for the demonstrators covers a comprehensive product homologation to meet TUV regulations and the requirements of OEMs and material suppliers. The market entry of the product is clearly detailed in the proposals business plan which predicts a commercially-available product within one year after the project ends. The strategy for implementing the carbon wheel on the market is a top-down approach starting with a low production volume for high class cars and a steady rise in carbon wheel production. The five-year goal is a production capability - only at RiBa - of 52.000 wheels per year by 2020. The technology also has the potential for transfer into higher-volume car segments in luxury/medium-class vehicles, as well as to helicopter and aviation applications. The industry-driven consortium is supported by strong partners integrated in an Industrial Exploitation Board (Bentley, Huntsman) providing technical and economic consulting and know-how. The project results will be systematically disseminated and exploited to maximize visibility, industrial take-up and the transfer of the developments to new markets.

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