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Doctoral Thesis
DOI
10.11606/T.18.2009.tde-15062009-091347
Document
Author
Full name
Rogério Carrazedo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2009
Supervisor
Committee
Coda, Humberto Breves (President)
Komatsu, José Sérgio
Laier, José Elias
Munaiar Neto, Jorge
Pavanello, Renato
Title in Portuguese
Estudo e desenvolvimento de código computacional para análise de impacto entre estruturas levando em consideração efeitos térmicos
Keywords in Portuguese
Método dos elementos finitos posicional
Termo-elasticidade
Termo-plasticidade
Abstract in Portuguese
Ao se estudar problemas de impacto de estruturas deformáveis, a consideração dos efeitos térmicos se faz muito importante, pois além de se observar a transformação de energia mecânica em calor pode-se considerar, ao longo do processo de análise, as mudanças das propriedades mecânicas do material envolvido devido ao aquecimento do meio. Neste sentido, o objetivo principal deste trabalho é o desenvolvimento de uma formulação termodinamicamente consistente e sua implementação computacional, baseada no potencial de energia livre de Helmholtz e na primeira e segunda leis da termodinâmica, para se analisar, via elementos finitos, o impacto entre estruturas com comportamento termo-elástico e termo-plástico. O problema mecânico será tratado com formulação posicional desenvolvida em projetos de pesquisa anteriores e que podem ser classificados como Lagrangeano total com cinemática exata. Para a modelagem do impacto utilizar-se-á a técnica do multiplicador de Lagrange associada à teoria potencial para previsão do impacto, técnica de retorno geometricamente definida e algoritmo de integração temporal de Newmark adequadamente adaptado para problemas gerais de impacto.
Title in English
Study and development of computational code to analyze impact in structures considering thermal effects
Keywords in English
Positional finite element method
Thermo-elasticity
Thermo-plasticity
Abstract in English
It becomes quite important study the thermal effects when considering impact in structures, because besides the mechanical energy changing into heat, one may consider the changes in the material properties due overheating. In this sense, the main goal of this work is develop a thermodynamic formulation and its implementation, based in the Helmholtz free-energy and in the first and second law of thermodynamics, to analyze structures under impact. The mechanical problem will be solved by a positional finite element application developed in past researches and it can be classified as a total Lagrangean with exact kinematics. In order to consider the impact, the Lagrangean multiplier will be associated to the potential theory of impact prevision, technique geometrically defined and an adapted technique based on the time integration of Newmark, modified to impact problems.
 
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Publishing Date
2009-06-15
 
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