Rapid prototyping and tooling in the manufacture of mould elements for large parts

In the last two decades the advances in rapid prototyping and tooling (RPT) technologies made possible the use of materials alternative to steel in some mould components. They also have allowed novel fabrication strategies and new ways of thinking on the production of injection moulds for short series of plas-tics parts. These technologies induced a new generation of toolmaking techniques. In the scope of the devel-opment project Hybridmould 21 the pros and cons of some RPT technologies were studied to fabricate moulding blocks and inserts for hybrid injection moulds for large plastics parts. Essentially, the studies aimed at finding the best solution for quick production and compliance with specific product requirements, such as complex features, complex cooling layout and large size (around 1 m2) in short production series. This paper discusses the main advantages and disadvantages associated to a number of different RPT technologies for the manufacture of moulding element.Program QREN - ‘Concessão de Incentivos Financeiros no âmbito do Sistema de Incentivos à Investigação e Desenvolvimento Tecnológico’ (contract 2010/013307) – Project Hybridmould 2

Comportamento de laminados multi-direccionais de CFRP para aplicações em engenharia civil

No âmbito do presente artigo são apresentados os resultados do desenvolvimento de laminados multi-direccionais de polímeros reforçados com fibras de carbono (MDL-CFRP) na reabilitação e reforço de estruturas de betão armado. A utilização de MDL-CFRP tem como objectivo fundamental permitir a introdução de ancoragens, de modo a aumentar a eficiência da ligação entre este material e os elementos a reforçar de acordo com a técnica AEBR (anchored and externally bonded reinforcement). Segundo esta nova técnica, os MDLCFRP são aplicados nas faces dos elementos a reforçar com recurso à colagem com adesivo e ao uso de ancoragens. Neste trabalho faz-se a descrição do processo de fabrico do MDLCFRP, e apresentam-se os resultados da caracterização geométrica e mecânica dos mesmos

Estudo comparativo entre modelos de previsão de resistência: leis analíticas versus data mining

Neste trabalho apresenta-se um estudo comparativo entre modelos de previsão da resistência de sistemas de polímeros reforçados com fibras (Fiber Reinforced Polymers – FRP) inseridos no betão de recobrimento de elementos de betão. Esta técnica é conhecida por Near-Surface Mounted (NSM). São analisados dois dos mais importantes códigos de projeto existentes e ainda modelos obtidos com recurso a algoritmos de data mining (DM). Os resultados obtidos demonstram que o recurso ao DM pode ser uma alternativa viável aos códigos existentes na previsão da resistência da ligação de sistemas FRP NSM

A review on the bond behavior of FRP NSM systems in concrete

This paper presents a review of current knowledge on the bond behavior of fiber reinforced polymer (FRP) systems inserted in the cover of concrete elements, commonly known as the near-surface mounted technique (NSM). In the first part, by studying the physics of the phenomenon, the typical failure modes, the most common bond tests and two of the most important design guidelines for FRP NSM systems are introduced. In the second part, a database of bond tests composed by 431 records is presented and the accuracy of existing design guidelines is assessed with this data. Lastly, the formulations proposed by these design guidelines are recalibrated based on the experimental results in the database.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT (Portuguese Foundation for Science and Technology) under the project CutInDur PTDC/ECM/11 2396/2009. The first author wishes also to acknowledge the Grant No. SFRH/BD/87443/2012 provided by FCT

Bond between concrete and multi-directional CFRP laminates

Recently, laminates of multi-directional carbon fiber reinforced polymers (MDL-CFRP) have been developed for Civil Engineering applications. A MDL-CFRP laminate has fibers in distinct directions that can be arranged in order to optimize stiffness and/or strength requisites. These laminates can be conceived in order to be fixed to structural elements with anchors, resulting high effective strengthening systems. To evaluate the strengthening potentialities of this type of laminates, pullout tests were carried out. The influence of the number of anchors, their geometric location and the applied pre-stress are analyzed. The present work describes the carried-out tests and presents and analyzes the most significant obtained results

Estudo comparativo de diferentes técnicas no reforço à flexão de vigas de betão armado com recurso a CFRP’s sob acções monotónicas e de fadiga

A aplicação de polímeros reforçados com fibras (FRP) no reforço à flexão de estruturas de betão armado (BA) tem sido realizada, essencialmente, com recurso às técnicas de colagem externa de mantas ou faixas de laminado (Externally Bonded Reinforcement – EBR) e de inserção de laminados ou varões no betão de recobrimento (Near-Surface Mounted – NSM). No âmbito do projeto em que este trabalho se insere pretende-se avaliar as potencialidades de uma técnica de reforço que consiste em, simultaneamente, colar e ancorar laminados multidireccionais de fibras de carbono na superfície de elementos de BA (Mechanically Fastened and Externally Bonded Reinforcement – MF-EBR). No presente trabalho apresentam-se e analisam-se os resultados de um programa de ensaios monotónicos e de fadiga realizado em vigas de BA reforçadas com laminados de CFRP segundo as técnicas EBR, NSM e MF-EBR. Adicionalmente, são também apresentados e analisados os resultados da simulação numérica dos ensaios monotónicos efetuados.O presente trabalho foi financiado pelos programas COMPETE e FEDER, projeto PTDC/ECM/74337/2006 da FCT – Fundação para a Ciência e a Tecnologia. Os autores manifestam os seus agradecimentos às empresas que gentilmente forneceram os materiais, nomeadamente, à Hilti Portugal – Produtos e Serviços Lda., à S&P Clever Reinforcement Ibérica Lda. e à SECIL, e à empresa TSwaterjet pelo corte dos laminados utilizando a tecnologia de jato de água

Efficiency of different techniques in seismic strengthening of RC beam-column joints

In the last years several techniques have been proposed and used for the seismic strengthening of reinforced concrete (RC) beam-column joints using fiber reinforced polymers (FRP). The Near Surface Mounted (NSM) technique uses FRP bars or laminates inserted into grooves opened on the concrete cover and filled with epoxy adhesive. In the Mechanically Fastened and Externally Bonded Reinforcement (MF-EBR) technique, multidirectional laminates of carbon fiber reinforced polymers (MDL-CFRP) are simultaneously bonded with epoxy adhesive and mechanically fixed with anchors to the faces of the elements to be strengthened. With the aim of comparing the seismic efficiency of NSM and MF-EBR techniques, tests with RC joints, representative of the buildings construction practice in Southern European countries until the early 1970s were carried. The experimental campaign comprises cyclic tests on seven full-scale RC joints with distinct configurations when both, NSM and MF-EBR techniques, are used. The tests are described and the main results are presented and analyzed

Seismic strengthening of beam-column joints with multi-directional CFRP laminates

Technical Report 11-DEC/E-13This work is supported by FEDER funds through the Operational Programme for Competitiveness Factors – COMPETE and National Funds through FCT – Portuguese Foundation for Science and Technology under the project PTDC/ECM/74337/2006. The authors acknowledge the materials generously supplied by Hilti Portugal - Produtos e Serviços Lda., S&P Clever Reinforcement Ibérica Lda. and SECIL

Laminados multi-direccionais de CFRP para aplicações em engenharia civil

Recentemente tem vindo a ser proposta uma nova técnica de reforço utilizando polímeros reforçados com fibras de carbono (CFRP) na reabilitação estrutural de estruturas de betão, que consiste na aplicação de laminados multi-direccionais de CFRP (MDL-CFRP). Estes laminados são simultaneamente colados e fixados mecanicamente através de ancoragens. Neste contexto, foi desenvolvido um MDL-CFRP e, para avaliar as suas potencialidades no reforço de estruturas de betão foram realizados ensaios de arranque directo. O presente trabalho descreve os ensaios realizados e analisa os principais resultados obtidos

Bond behavior between concrete and multi-directional CFRP laminates using the MF-EBR strengthening technique

The strengthening technique based on the application of multi-directional laminates of CFRP (MDL-CFRP) simultaneously glued and anchored to the surface of the elements to be strengthened has been recently proposed. This technique was designated Mechanically Fastened and Externally Bonded Reinforcement (MF-EBR) and combines the fasteners from the MF-FRP technique with the externally glued properties from the EBR. With the aim of assessing the potentialities of this technique for seismic retrofitting, three interior RC beam-column joints were strengthened according to the MF-EBR technique and tested. This work presents the entire test program executed, including test configuration, results and corresponding analysis.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/ECM/74337/2006.FEDER- Operational Program for Competitiveness Factors – COMPET