Papers by Author: Carlos Capela

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Authors: Amilcar Ramalho, José Domingos M. Costa, José A. Martins Ferreira, Carlos Capela
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Authors: Joao P. Nobre, António Castanhola Batista, Carlos Capela, Marcelo Calvete Gaspar
Abstract: The presented study was carried out in an industrial environment, using existing equipments, tools and materials. A set of tests was performed based on production demands and restrictions, aiming to achieve the lowest surface roughness and beneficial residual stress state. The experimental test surfaces were obtained using high-speed milling (HSM) and precision surface grinding on a DIN X 36 CrMo 17 steel work piece, widely used in injection moulding industry. The grinded surface was considered as a reference surface in order to evaluate the high-speed milling performance. For HSM tests, two types of tools were selected: tungsten carbide end mills with and without a TiAlN multilayer coating. The selected HSM main parameters ranged an upper, middle and lower limit value, considering the standard working values. The residual stress state at machined surfaces was evaluated by X-ray diffraction (XRD). Experimental results are discussed in order to achieve a procedure to select the optimal machining parameters that meet manufacturing specifications.
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Authors: Carlos Capela, José A. Martins Ferreira, José Domingos M. Costa
Abstract: Low-density sheet moulding compounds incorporating hollow glass micro-spheres are being increasing used namely in automotive industry, boats and deep-water submarines and core materials. This paper presents the results obtained in a current study of the viscous properties on hybrid short fibre/hollow glass microspheres composites fabricated with epoxy binder. Dynamic mechanical analysis (DMA) was used to study the effect of the filler volume fraction and of the addition of glass fibre reinforcement on the dynamic stiffness modulus, damping coefficient and glass transition temperature in tensile mode. The specimens were cut from plates produced by resin transfer moulding in vacuum with microspheres weight contents up to 13%. Elastic modulus decreases significantly with the increasing of filler volume fraction. In contrary, it increases significantly with the glass fibre reinforcement content. Glass transition temperature apparently tends to decrease with microspheres and of glass fibre reinforcement’s content. Tmax temperatures tend to increase slightly with the addition of fibre reinforcements and the microsphere filler. Maximum damping coefficient is much lower for the foams when compared with net resin.
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