TEMM2018 Porto (Portugal), 4 - 7 Novembro 2018 |
TEMM2018 Porto (Portugal), 4 - 7 Novembro 2018 |
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Palestras Plenárias The CNME2018 / TEMM2018 program will include a number of Keynote Lectures by distinguished professionals and scientists in the different areas covered by the Main Topics and Symposia of the congress / conference, to provide thematic presentations of their most recent findings and developments.
Professor Paulo Tavares de Castro Professor Catedrático da FEUP/DEMec Universidade do Porto, Portugal Email: ptcastro@fe.up.pt
He is currently a full professor in the Department of Mechanical Engineering at FEUP. His research interests are mainly in the field of fatigue, fracture and structural integrity. Through a number of r&d projects funded by the European Union, a substantial part of his research in recent years is related to aeronautics, mainly riveted structures and, more recently, integral structures, particularly those made with FSW. Professor de Castro has been involved in several national and international scientific and professional associations, such as ASME, where he was a member of the Board on Professional Practice and Ethics, TWI, IOM3, SEFI, Ordem dos Engenheiros, among others. He is a corresponding member of the Lisbon Academy of Sciences and a member of the editorial board of the journals Fatigue and Fracture of Engineering Materials and Structures, International Journal of Structural Integrity, Mechanika, UPB Scientific Bulletin Series D: Mechanical Engineering, among others. He had sabbaticals as Fulbright Scholar at the University of California at Berkeley, and as visiting scholar at Lehigh University, and presented invited lectures at Imperial College London, Lehigh University, Univ. California at Berkeley, Univ. of Maryland and Univs. Federal of Rio de Janeiro, Coimbra, Lille, Napoli, and Salerno, among others. He was professeur invité of the Université des Sciences et Technologies de Lille, and consultant for Univ. Eduardo Mondlane. Up to now, his university management activities (always at FEUP) include being director of the degree in Mechanical Engineering (pre Bologna), of the doctoral program in Mechanical Engineering, and of the Department of Mechanical Engineering twice. He has been a member of the board of directors of the Innovation Agency (Agência de Inovação) since the creation of this organization in 1993 until 1996.
Title of Presentation
FATIGUE OF METALLIC STRUCTURES, WITH A FOCUS ON THE CASE OF AIRFRAMES
ABSTRACT
Damage-tolerance is the main design approach for airframes, making possible weight savings and structural integrity assurance in the presence of eventual damage resulting from manufacturing or developed in service. Damage-tolerance approach relies upon databases of fatigue and fracture properties, corrosion behavior, failure modes and nondestructive inspection, particularly minimum detectable defect size and inspection intervals. When inspection is impossible or multiple load paths are unavailable, then the older safe life design approach needs to be used – that is the case of certain airframe details and of the landing gear. The presentation will review the topic of fatigue of airframes highlighting issues as materials choice (Al alloys including Al-Li, composites …), mixed mode crack propagation testing and modelling, residual stresses and integral metallic structures, in the context of the evolution of the applicable regulations (FAA and EASA). Fatigue life evaluations are at the core of safety considerations in design of airframes. To face scatter in material properties, conservative approaches considering the worst scenario or statistical methods dealing with the variability of material have been employed in the fatigue assessment of structures. This will be illustrated by an example of a fracture mechanics calculation. Most work on fatigue involves mode I situations, but in practice mixed mode situations are frequently found. X-FEM (extended finite element method) may be used to predict the crack path under mixed mode loading situations. Several mixed mode I-II studies will be discussed, including modified compact tension and three-point bend as well as the four point cracked bend specimen; in certain circumstances, the last type allows for pure mixed mode II evaluations (similarly to the Iosipescu notched specimen), Figure 1. Different approaches to calculate the equivalent stress intensity factor were studied and a comparison between Richard/Henn, Energy, Tanaka and Chen approaches was performed. Residual stresses have an important impact upon the fatigue behaviour of a structure. The measurement of residual stresses may be made with high accuracy using neutron diffraction or synchrotron x-ray techniques. Recently, the so called contour method, 2 invented by Prime at Los Alamos National Laboratory, has been the object of great interest and gained wide acceptance as a destructive method capable of accurate determination of residual stress. Although rather time consuming, the contour method is an inexpensive alternative for residual stress measurement when compared with the techniques previously mentioned; this will be discussed in the context of worked examples. The problem of residual stresses is of particular importance for integral structures, as those resulting from the use of friction stir welding. Some results with application in aeronautics will be discussed. After a survey of technical details, the talk concludes with reference to the regulatory environment: The 2010 FAA rule establishing a limit of validity (LOV) puts a bound in the indefinite operational life allowed for by earlier regulations. This requirement, together with the diminishing role of Al alloys in airframes, will certainly shape the directions of fatigue, fracture and damage mechanics research in years to come.
Figure 1 - Example of crack turning due to variation of mode mixicity: detail of a four point bend cracked specimen fatigue tested. (from: Lucas Gicquel, Polytech Lille student internship at FEUP, 2017 under supervision of Sérgio M.O. Tavares and Paulo M.S.T. de Castro)
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Investigador Auxiliar do LNEC Núcleo de Modelação e Mecânica das Rochas / Departamento de Barragens de Betão Email: jgomes@lnec.pt
2006 – Doutoramento em Ciências de Engenharia Civil pela Universidade Federal do Rio de Janeiro; 2006 - Grau de Especialista em Barragens do LNEC; 1996 – Assistente de Investigação do LNEC; 1990 - Licenciatura em Engenharia Civil pelo Instituto Superior Técnico, ramo Estruturas; 1987 - Bacharelato em Engenharia Civil pelo Instituto Superior de Engenharia de Lisboa.
Funções e Cargos Públicos Relevantes 2001 - Professor convidado no ISEL Equiparado a Professor Adjunto; 2006 - Investigador Auxiliar do LNEC; 1999 – Professor convidado no ISEL Equiparado a Assistente do 2º Triénio; 1996 - Assistente de Investigação do LNEC; 1992 - Estagiário de Investigação do LNEC; 1989 - Bolseiro de Investigação do LNEC;
Áreas de Investigação / Interesse Modelação experimental; Modelação física de barragens de betão envolvendo cenários de rotura para ações estáticas e dinâmicas; Modelação numérica de barragens de betão envolvendo cenários de rotura para ações estáticas e dinâmicas; Avaliação do comportamento dinâmico das estruturas através da realização de ensaios no protótipo; Observação da atividade sísmica; Observação do comportamento real de estruturas sujeitas a ações dinâmicas.
Título da Apresentação
PROJECTO, CONSTRUÇÃO E EXPLORAÇÃO DE BARRAGENS DE BETÃO
RESUMO
O Laboratório Nacional de Engenharia Civil (LNEC), desde a sua criação, em 1946, tem dado um apoio significativo ao projeto, à construção e à exploração de barragens de betão e obras subterrâneas associadas, tanto em Portugal como no estrangeiro. Esta atividade tem sido muito diversificada e abrange todas as fases de vida da obra, podendo salientar-se os estudos e atividades relacionados com a caracterização dos maciços rochosos, a definição de formas estruturais e hidráulicas, utilizando modelação física e matemática, a análise estrutural por métodos experimentais e numéricos, a observação do comportamento e o controlo da segurança das obras. No sentido de reduzir a dependência energética de Portugal, nos últimos anos tem vindo a ser aumentada a capacidade de produção hidroelétrica, com o reforço de potência de aproveitamentos existentes e com a construção de novos aproveitamentos. Destacam-se cinco reforços de potência e novos aproveitamentos que integram doze grandes barragens de betão. Devido às suas valências, o LNEC foi solicitado para dar apoio ao projeto estrutural e hidráulico e à implementação do plano de observação das obras. Decorrente das suas atribuições no Regulamento de Segurança de Barragens (RSB), o acompanhamento do comportamento das obras pelo LNEC prossegue no primeiro enchimento da albufeira, que constitui um verdadeiro ensaio de carga das estruturas e fundações, e prolonga-se nas fases de exploração e eventual abandono e demolição, por forma a garantir-se a segurança em todas as fases de vida. Para tal dispõe de um sistema integrado de arquivo e gestão da informação relativa à observação do comportamento das obras, que suporta o controlo da segurança nas vertentes estrutural, hidráulica e ambiental. A intervenção do Departamento de Barragens de Betão (DBB) do LNEC no apoio ao projeto estrutural destas obras envolveu um vasto conjunto de atividades, nomeadamente o estudo dos maciços rochosos, os estudos em modelo matemático para análise da segurança estrutural, considerando os três cenários principais (as ações sísmicas, a degradação do betão e a rotura pelo maciço rochoso de fundação) e a elaboração de planos de observação. A atividade do LNEC na construção das obras tem sido de carácter diversificado, nomeada- mente na caracterização do comportamento de materiais, no acompanhamento das escavações de fundações e de obras subterrâneas associadas e na implementação dos planos de observação.
Professor Catedrático da FEUP/DEC Universidade do Porto, Portugal Email: acunha@fe.up.pt
Professor Álvaro Cunha is the Head of Laboratory of Vibrations and Monitoring of FEUP (ViBest, www.fe.up.pt/vibest) , which is is a facility / research unit of the Civil Engineering Department of FEUP that provides support to the performance of experimental and numerical works in the context of the development of research , consultancy and teaching activities in the field of Structural Dynamics, aiming in particular the experimental characterization of vibratory phenomena, the analysis, identification, monitoring and control of the structural behavior of bridges and special Civil structures under different types of dynamic loads.
He has been the leader of ten national or european Research Projects during the last fifteen years, focused on the themes: (1) Dynamic measurements with Laser sensors, (2) Modal Identification of Large Structures and Finite Element Updating, (3) Dynamics of Cable-Stayed Bridges, (4) Dynamic Effects of Traffic Loads on Bridges, (5) Wind and Structures, (6) Fatigue assessment in metallic Railway Bridges, (7) Vibrations in Footbridges, (8) Control of Vibrations in Civil Structures, (9) Structural Health Monitoring, (10) Deterioration of Dams.
Professor Álvaro Cunha has been also the main Responsible for scientific and technical consultancy to different entities, such as structural designers, construction companies, national transport agencies and production industries, in the following main topics: Dynamic testing of bridges and special structures; Output-only modal identification and finite element model updating; Dynamics of cable-stayed bridges, Control of cable vibrations; Dynamic behaviour of suspended roofs; Bridge aerodynamics; Traffic induced effects and fatigue assessment in railway and road bridges; Dynamic behaviour of lively footbridges; Assessment, control and monitoring of vibrations in footbridges; Long-term dynamic monitoring of bridges, dams and special structures; Technological innovation in remote structural monitoring.
Title of Presentation
CONTINUOUS DYNAMIC MONITORING OF LARGE CIVIL INFRASTRUCTURES
ABSTRACT
The Laboratory of Vibrations and Structural Monitoring (ViBest, www.fe.up.pt/vibest ) of CONSTRUCT/FEUP has been implementing, since 2007, a significant set of long-term dynamic monitoring systems in large Civil structures with different typologies (e.g. roadway, railway and pedestrian bridges, stadia suspension roofs, wind turbines, concrete dams or high voltage transmission lines). This paper briefly describes some of these applications, clearly illustrating the interest and potential of the developed technology, as well as of the huge high quality database created, which can be used for joint collaborative research at European level. The representative set of monitoring applications presented shows the efficiency of the developed tools and the usefulness of the testing and monitoring programs implemented, enabling the achievement of different objectives, such as: (i) the development of finite element model correlations and updating; (ii) the vibration serviceability safety checking, particularly in case of lively bridges involving the inclusion of vibration control devices; (iii) the implementation of automated versions of the most powerful methods of Operational Modal Analysis, and their application for tracking the time evolution of modal parameters in long-term dynamic monitoring applications; (iv) the application of statistical methods to remove the influence of environmental and operational factors (e.g. temperature, intensity of traffic, wind) on the modal variability, supporting the development of reliable techniques for vibration based damage detection; (v) the experimental assessment of fatigue, based on the measurement of effects of real traffic loads; (vi) the experimental assessment of aerodynamic problems in bridges based on in-situ measurements; (vii) the tracking of modal parameters in wind turbines, enabling damage detection and fatigue assessment and (viii) the characterisation of the influence of the water level in the reservoir on the dynamic properties of concrete arch dams.
Professor Catedrático Universidad Carlos III de Madrid, España Email: ebarbero@ing.uc3m.es
He is the Head of the research group "Mechanics of Advanced Materials (MECMA)" since 2006, and a full professor in the Department of Solid Mechanics and Structural Analysis since 2011, of Universidad Carlos III de Madrid. His research interests are mainly focused on the impact and damage tolerance of composite structures, joints and repairs of composites, smart structures and structural response of biocomposites. These research activities are carried with several international partners. The analysis of mechanical behaviour of repaired composite structures is made in collaboration with the Department of Aerospace Engineering of West Virginia University (USA). The research in the structural response of biocomposites is carried out with the Department of Mechanical Engineering of the University of Coimbra (Portugal) and Department of Aerospace Engineering of the La Sapienza University of Rome (Italy). Professor Barbero has leaded in various research projects with public and private funding. He has collaborated with several National Research Centres and Companies in the aeronautical sector, such as INTA, Airbus, Aernnova or Iberespacio.
Title of Presentation
MECHANICAL BEHAVIOUR OF BONDED REPAIRED COMPOSITE PLATES
ABSTRACT
The Mechanics of Advanced Materials research group is made up of a multidisciplinary team of Aeronautical, Civil, Mechanical and Materials Engineers. The group works integrating theory, experiment and computational modelling. Major themes are analysis and modelling of composite structural elements subjected to dynamic loads, as well as the study of damage tolerance. The group has extensive experience in developing special testing methodologies. Laminates are widely used in aircraft structures as a result of their excellent mechanical and specific properties. The use of laminates leads to measurable reduction of the structural weight as well as lower fuel consumption; such operational adjustments increase the efficiency of aircrafts, and reduce pollution emissions. Structural elements of aircrafts are susceptible to damage during their service life. Complete replacement of damaged components is not always feasible, due to the high level of integration and the big size of the structural components. Therefore, repair and subsequent put into operation of composite structures, can be cost-effective and less time-consuming. Currently, the only certified repairs in air transport sector are bolted repairs. However, bonded repairs can restore greater strength to a damaged composite structure and show some advantages as compared to bolted repairs. In addition, external bonded patches are suitable for thin composite laminates. Consequently, the need to gain knowledge about their behaviour under service loading is readily apparent. In this work the mechanical behaviour of adhesively bonded repaired composite plates, and the evaluation of their damage tolerance to low-velocity impact were analysed. A combined experimental and numerical study was carried out. The influence of the main parameters of an adhesive bonded repair on the strength, stiffness and failure mechanisms under static and dynamic loads, are evaluated .
Page created on 10 July 2017 / Last update on 10 January 2018
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