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Master's Dissertation
DOI
10.11606/D.3.2007.tde-08082007-165939
Document
Author
Full name
Marco Antonio Brujas
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Brasil, Reyolando Manoel Lopes Rebello da Fonseca (President)
Buelta Martinez, Miguel Angel
Gonçalves, Paulo Batista
Title in Portuguese
Análise numérica e experimental dos efeitos da não-uniformidade da espessura em cascas finas cilíndricas rotativas.
Keywords in Portuguese
Análise experimental
Cascas cilíndricas
Elementos finitos
Ferro fundido cinzento
Ultra-som
Variação de espessura
Abstract in Portuguese
Cascas cilíndricas circulares com uma pequena variação de espessura ao longo de seu comprimento, quando submetidas à rotação, apresentam em alguns casos, deslocamentos elásticos de sua superfície externa, tendendo a uma forma de um oval. O objetivo deste trabalho é estabelecer a relação entre a variação de espessura das cascas cilíndricas com a sua deformação devida às forças centrífugas medida durante a rotação utilizando-se dois enfoques, um experimental e outro numérico, no caso o método de elementos finitos (MEF). As cascas cilíndricas estudadas tiveram sua espessura de parede medidas por meio de aparelho de ultra-som, mas por serem fabricadas em ferro fundido cinzento, as suas lamelas de grafita atuam como refletores, o que torna a medição imprecisa. Os resultados da análise numérica encontrados se relacionam bem com os experimentais de maneira qualitativa, mas divergem na forma quantitativa. Modelos de cascas com variação de espessura imposta também foram criados e analisados usando-se o método de elementos finitos de forma a se avaliar o comportamento da casca cilíndrica sob diversas configurações de distribuição da variação da espessura. Sugere-se a pesquisa de novas tecnologias para medições por ultra-som de peças fabricadas de ferro fundido com grafita lamelar. Neste trabalho, a medição da forma oval foi feita utilizando-se sensores de proximidade do tipo "eddy-current".
Title in English
Numerical and experimental analysis of the thickness non-uniformity effects in rotating circular cylindrical shells.
Keywords in English
Cylindrical shells
Experimental analysis
Finite elements method
Flake graphite cast iron
Thickness variation
Ultrasound
Abstract in English
Circular cylindrical shells with small thickness variations along their body, when submitted to rotation, present, in some cases, elastic displacements of their outside surface induced by centrifugal forces leading to final oval like shapes. The main purpose of this study is to establish relationships between thickness variation of the cylindrical shells with their measured deformation during the rotation, due to centrifugal forces, using two approaches, one experimental and the other one numerical, in the latter case the finite element method (FEM). The studied cylindrical shells had their wall thickness measured by means of an ultrasound device. The used material is flake graphite cast iron (gray cast iron). The graphite flakes act as reflectors, what makes such measurements imprecise. The numerical results found are satisfactory in a qualitative way, but they disagree in the quantitative form. Shell models with theoretical imperfections also were created and analyzed using the finite element method in order to evaluate the behavior of the cylindrical shell under several configurations of distribution of the shell thickness variation. Further research is necessary on new technologies to measure the thickness of pieces manufactured of flake graphite cast iron. In this research, the oval shape measurements were done by means of eddy-current proximity sensors.
 
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Publishing Date
2007-08-29
 
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