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- Processo de aglomeração de cortiça, em formas complexas, sem recurso a aglutinantes, por compressão a quentePublication . Martins, Fábio Miguel Cardoso; Silva, João F.A presente invenção tem aplicação direta na indústria corticeira e refere-se a Um processo de aglomeração de granulados de cortiça, provenientes de falcas, sem Recurso à adição de aglutinantes. São obtidas formas complexas, em série, utilizando Moldes que permitem conceber a forma final sem necessidade de qualquer operação de Acabamento, ou procedimentos adicionais de desbaste.os seus campos de aplicação são Variados, considerando as diversas utilizações dos aglomerados de cortiça. Contudo, a Maior parcela deverá corresponder a:- decoração ¿ peças decorativas de formas Complexas; - isolamentos ¿ peças de pequena e média dimensão para automóveis, indústria Aeroespacial, mecanismos de refrigeração ou caldeiraria.tendo em conta que o estado da Arte atual caracteriza-se pela aglomeração prévia em formas simples com posterior Maquinação na forma final pretendida, a obtenção de peças complexas recorrendo a um Procedimento com menor número de etapas e sem geração de desperdício, constitui a Grande evolução deste processo.
- Delamination analysis of carbon fibre reinforced laminates: evaluation of a special step drillPublication . Marques, A. T.; Durão, Luís M.; Magalhães, A. G.; Silva, João F.; Tavares, João Manuel R. S.Drilling of carbon fibre/epoxy laminates is usually carried out using standard drills. However, it is necessary to adapt the processes and/or tooling as the risk of delamination, or other damages, is high. These problems can affect mechanical properties of produced parts, therefore, lower reliability. In this paper, four different drills – three commercial and a special step (prototype) – are compared in terms of thrust force during drilling and delamination. In order to evaluate damage, enhanced radiography is applied. The resulting images were then computational processed using a previously developed image processing and analysis platform. Results show that the prototype drill had encouraging results in terms of maximum thrust force and delamination reduction. Furthermore, it is possible to state that a correct choice of drill geometry, particularly the use of a pilot hole, a conservative cutting speed – 53 m/min – and a low feed rate – 0.025 mm/rev – can help to prevent delamination.
- Pultrusion of fibre reinforced thermoplastic pre-impregnated materialsPublication . Novo, P.J.; Silva, João F.; Nunes, J.P.; Marques, A.T.Fibre reinforced thermoplastic pre-impregnated materials produced continuously by diverse methods and processing conditions were used to produce composites using pultrusion. The processing windows used to produce these materials and composites profiles were optimized by using the Taguchi/DOE (Design of Experiments) methods. Those composites were then submitted to mechanical testing and microscopy analysis. The obtained results were compared with the expected theoretical ones predicted from the Rule Of Mixtures (ROM) and with those of similar engineering conventional available materials. The results obtained shown that produced composites have adequate properties for applications in common and structural engineering markets.
- Processing of carbon reinforced thermoplastic pre-impregnated materialsPublication . Novo, P. J.; Nunes, J. P.; Silva, João F.; Marques, A. T.The aim of this work is to produce and optimize the processing of carbon fibres thermoplastic matrix pre-impregnated materials (towpregs and PCT´s). Pultrusion and heated compression moulding were the selected manufacturing methods for processing all carbon fibres thermoplastic matrix pre-impregnated materials into composite parts. The optimization of those processes was made by studying the influence of the most relevant processing parameters in the final properties of the produced carbon fibres thermoplastic matrix pre-impregnated materials and composites. The method of Taguchi / DOE (Design of Experiments) was used to achieve this aim as it allowed making more rational choices of processing windows. The composite relevant mechanical properties were determined and studied. The final composites were also submitted to SEM microscopy analysis.
- Advanced Thermoplastic Carbon Fibre Reinforced Pultruded CompositesPublication . Novo, P. J.; Silva, João; Nunes, J. P.; Marques, A. T.The aim of this work is to optimize the production of new continuous carbon fibers reinforced thermoplastic matrix pre-impregnated materials (towpregs) continuously processed by dry deposition of polymer powders in a new equipment developed by the Institute for Polymers and Composites (IPC). The processing of the produced towpregs by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP), was also optimized. Two different thermoplastic matrices were studied: one for commercial applications (polypropylene) and another for advanced markets (Primospire®). The optimization was made by studying the influence of the most relevant processing parameters in the final properties of the produced towpregs and composites. The final pultruded composite profiles were submitted to mechanical tests in order to obtain relevant properties.
- Processing of pre-impregnated thermoplastic towpreg reinforced by continuous glass fibre and recycled PET by pultrusionPublication . Asensio, M.; Esfandiari, Puria; Núñez, K.; Silva, J. F.; Marques, A.; Merino, J.C.; Pastor, J.M.Packaging sector generates 40% of the plastics consumption in Europe. Among the most consumed plastics, polyethylene terephthalate (PET) is still the material that undoubtedly continues to grow in the packaging sector. Hence, there is a concern related to the recycling process, which today is only around 56%. Therefore, the objective of this work focuses on the use of this recycled material as a source of raw material for pultrusion processes. This work studies and compares the processability of final composite pultruded parts by using three different pre-impregnated recycled materials different in their viscosity and stream. Those composites were characterized by mechanical testing and microscopy analysis. The obtained results were compared with those of another pultruded thermoplastic (polypropylene) composite. From this study, it was possible to transform a waste into a product with high added value, reducing the carbon footprint.
- Sandwiched composites in aerospace engineeringPublication . Nunes, J.P.; Silva, João F.This chapter considers sandwiched composites used in aerospace applications. It discusses new developments in the types of face and core materials, production methods and joining and repair techniques. It also discusses various properties as well as their main design methods. Both existing and future applications of sandwiched composites are discussed.
- Thermoplastic matrix composites – new generation of eco-friendly materialsPublication . Esfandiari, Puria; Silva, João; Novo, P. J.The biggest advantagein the use of thermoplastic composites is the possibility of recycling and reprocessing, which is not possible with thermosetting composites. The shorter manufacturing cycle time and lower chemical emissions are, as well, other advantages. The use of thermoplastic matrix composites creates new engineering challenges concerning the manufacturing due to their high viscisity during manufacture. For all the advantages that these materials present, it becomes useful to study and evolve the universe of composites in the direction of thermoplastics. In this work, continuous fiber thermoplastic composites were produced and transformed by pultrusion and heated compression moulding. The manufactured composites were then tested, and mechanical properties were determined and studied.
- Producing LFT composite parts for large consumption markets from thermoplastic powder-coated towpregsPublication . Nunes, J. P.; Rodrigues, F. M.; Novo, P. J.; Silva, João F.Thermoplastic matrix composites are receiving increasing interest in last years. This is due to several advantageous properties and speed of processing of these materials as compared to their thermoset counterparts. Among thermoplastic composites, Long Fibre Thermoplastics (LFTs) have seen the fastest growth, mainly due to developments in the automotive sector [0, 2]. LFTs combine the (semi-)structural material properties of long (>1 cm) fibres, with the ease and speed of thermoplastic processing. This paper reports a study of a novel low-cost LFT technology and resulting composites. A patented powder-coating machine [3, 4] able to produce continuously pre-impregnated materials directly from fibre rovings and polymer powders was used to process glass-fibre reinforced polypropylene (GF/PP) towpregs. Such pre-impregnated materials were then chopped and used to make LFTs in a patented low-cost piston-blender developed by the Centre of Lightweight Structures, TUD-TNO, the Netherlands [5, 6]. The work allowed studying the most relevant towpreg production parameters and establishing the processing window needed to obtain a good quality GF/PP powder coated material. Finally, the processing window that allows producing LFTs of good quality in the piston-blender and the mechanical properties of final stamped GF/PP composite parts were also determined.
- Processing of continuous fibre reinforced thermoplasticsPublication . Nunes, J. P.; Silva, João F.; Marques, A. T.Towpregs based on different fibres and thermoplastic matrices were processed for highly demanding and more commercial applications by different composite processing technologies. In the technologies used, compression moulding and pultrusion, the final composite pr ocessing parameters were studied in order to obtain composites with adequate properties at industrial compatible production rates. The produced towpregs were tested to verify its polymer content and degree of impregnation. The obtained results have shown t hat the coating line enabled to produce, with efficiency and industrial scale speed rates, thermoplastic matrix towpregs that may be used to manufacture composites for advanced and larger volume commercial markets.