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Master's Dissertation
DOI
Document
Author
Full name
Eduardo Barjud Bugelli
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2010
Supervisor
Committee
Driemeier, Larissa (President)
Lombardi Junior, Arley de Barros
Machado, Izabel Fernanda
Title in Portuguese
Modelos de falha em análise numérica de estrutura veicular submetida a impacto de baixa velocidade.
Keywords in Portuguese
Impacto de baixa velocidade
Modelos de falha
Pára-choque
Ruptura dúctil
Abstract in Portuguese
O presente trabalho visa o estudo e avaliação de diversos modelos de falha através de ensaios experimentais e análises numéricas. A caracterização do material foi feita por meio de ensaios de tração de espécimes com e sem entalhe e de cisalhamento, para prover dados em uma ampla faixa de triaxialidade. A calibração dos parâmetros necessários para cada modelo de falha ocorreu através da obtenção das componentes de tensões e de deformações na região de ruptura, obtidas por meio de análises numéricas destes ensaios. O critério da máxima deformação plástica equivalente, modelo de dano de Johnson-Cook e critério da máxima tensão cisalhante foram aplicados em um caso de impacto em pára-choque. Diversos ensaios de impacto foram realizados até a que se atingisse a ruptura satisfatória do componente. Os ensaios foram modelados em elementos finitos, através do programa comercial LS-Dyna®, sendo que os modelos de falha calibrados foram aplicados para o ensaio onde se ocorreu ruptura. Houve boa concordância entre os resultados obtidos numericamente e experimentalmente, respeitadas as observações realizadas acerca da especificidade deste caso de impacto em baixa velocidade.
Title in English
Numerical simulations and experiments of vehicle structures under low speed crash loadings to evaluate fracture models.
Keywords in English
Bumper beam
Ductile fracture
Fracture criterion
Low speed crash
Abstract in English
The aim of the present work is an assessment of several fracture models through experiments and numerical simulations. Tensile tests with notched and unnotched specimens were carried out to provide the material characterization in a wide range of stress triaxiality. The calibration of the parameters required by the fracture models was enabled by the parallel numerical simulation of the tensile tests, providing information on the stress and strain components at the failure locus. The constant equivalent strain criterion, the Johnson-Cook failure model and the maximum shear stress failure criterion were applied in a bumper beam impact case study. Several low speed impact tests were carried out in order to result in the components rupture. Numerical simulation of the experiments was performed using commercial finite element code LS-Dyna®. Good correlation of experiments and numerical simulations was achieved when considering this particular low speed case study.
 
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Publishing Date
2010-08-31
 
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