Analyzing objects in images for estimating the delamination influence on load carrying capacity of composite laminates

The use of fiber reinforced plastics has increased in the last decades due to their unique properties. Advantages of their use are related with low weight, high strength and stiffness. Drilling of composite plates can be carried out in conventional machinery with some adaptations. However, the presence of typical defects like delamination can affect mechanical properties of produced parts. In this paper delamination influence in bearing stress of drilled hybrid carbon+glass/epoxy quasi-isotropic plates is studied by using image processing and analysis techniques. Results from bearing test show that damage minimization is an important mean to improve mechanical properties of the joint area of the plate. The appropriateness of the image processing and analysis techniques used in the measurement of the damaged area is demonstrated.

Modelação da furação de laminados por elementos finitos

Furação de estruturas em compósitos de matriz polimérica

Avaliação de ferramentas na furação de laminados compósitos

Drilling of polymeric matrix composite structures

Modelação de aplicações SIG com aspectos

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Informática

Delamination analysis of carbon fibre reinforced laminates: evaluation of a special step drill

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.

Maquinagem não convencional sobre placas compósitas

A utilização de materiais compósitos tem crescido nas últimas décadas em virtude do seu baixo peso, elevada resistência e rigidez. A furação de placas compósitas é um desafio que se coloca às indústrias que trabalham com este tipo de materiais, sendo frequente o recurso a ferramentas convencionais, normalmente utilizadas na construção mecânica, com adaptações. Neste trabalho, apresenta-se uma técnica não convencional baseada na furação por jacto de areia sendo avaliadas as descontinuidades causadas em placas compósitas. Durante este processo de furação, as camadas da placa não resistem o tempo necessário para concluir a perfuração, aquecendo e fragmentando- se, e a areia, com o impacto, perde rapidamente o poder abrasivo. Além disso, o tempo necessário para completar com sucesso a operação seria superior a 5 horas, uma vez que a primeira etapa de jateamento durou aproximadamente uma hora, sendo necessário no fim da mesma repor um novo isolamento devido desgaste sofrido. Nesse momento da operação o progresso obtido era imperceptível. O trabalho experimental realizado permite concluir que a furação por jacto de areia, utilizando um compressor com um caudal de 1700 l/min e jateadora de sucção, não se mostra uma ferramenta promissora para executar operações de furação em placas compósitas.

Tool geometry evaluation for carbon reinforced composite laminates

The use of composite laminates in complex structures has increased significantly. However, there are still some issues when considering their use, mainly related with machining, leading to some difficulties and lack of acceptance. In this work, a methodology to evaluate drill geometry and feed rate based on thrust force and delamination extension is presented.

Evaluation of tools and cutting conditions on carbon fibre reinforced laminates

The distinctive characteristics of carbon fibre reinforced plastics, like low weight or high specific strength, had broadened their use to new fields. Due to the need of assembly to structures, machining operations like drilling are frequent. In result of composites inhomogeneity, this operation can lead to different damages that reduce mechanical strength of the parts in the connection area. From these damages, delamination is the most severe. A proper choice of tool and cutting parameters can reduce delamination substantially. In this work the results obtained with five different tool geometries are compared. Conclusions show that the choice of an adequate drill can reduce thrust forces, thus delamination damage.

Drilling damage in composite material

The characteristics of carbon fibre reinforced laminates have widened their use from aerospace to domestic appliances, and new possibilities for their usage emerge almost daily. In many of the possible applications, the laminates need to be drilled for assembly purposes. It is known that a drilling process that reduces the drill thrust force can decrease the risk of delamination. In this work, damage assessment methods based on data extracted from radiographic images are compared and correlated with mechanical test results—bearing test and delamination onset test—and analytical models. The results demonstrate the importance of an adequate selection of drilling tools and machining parameters to extend the life cycle of these laminates as a consequence of enhanced reliability.

Estudo da biodegradação do ácido 2,4- diclorofenoxiacético, um herbicida selectivo amplamente utilizado na agricultura, por uma estirpe de Penícillium

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Tecnologia e Segurança Alimentar

Acqusition and data analysis of the eco-efficiency for the establishment of indicators parameters for industrial environmental sustainability

The industrial activity is inevitably associated with a certain degradation of the environmental quality, because is not possible to guarantee that a manufacturing process can be totally innocuous. The eco-efficiency concept is globally accepted as a philosophy of entreprise management, that encourages the companies to become more competitive, innovative and environmentally responsible by promoting the link between its companies objectives for excellence and its objectives of environmental excellence issues. This link imposes the creation of an organizational methodology where the performance of the company is concordant with the sustainable development. The main propose of this project is to apply the concept of eco-efficiency to the particular case of the metallurgical and metal workshop industries through the development of the particular indicators needed and to produce a manual of procedures for implementation of the accurate solution.

Organização e estruturação do conhecimento para a tradução jurídica: Português e Espanhol

Tese apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Ciências da Linguagem (área de especialização Lexicologia e Lexicografia)

Implementação do controlo estatístico do processo no fabrico de mixes de cremes de pasteleiro

Dissertação apresentada para obtenção do grau de Mestre em Tecnologia e Segurança Alimentar – Qualidade Alimentar pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Gestor de bairro: contributo para a sustentabilidade local

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia do Ambiente, perfil Ordenamento do Território e Impactes Ambientais

Contribuição da microbiologia preditiva na análise de cremes de pasteleiro

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Tecnologia e Segurança Alimentar