Estudo de efeitos dinâmicos até o início da fratura frágil
| Ano de defesa: | 2007 |
|---|---|
| Autor(a) principal: | |
| Orientador(a): | |
| Banca de defesa: | |
| Tipo de documento: | Dissertação |
| Tipo de acesso: | Acesso aberto |
| Idioma: | por |
| Instituição de defesa: |
Universidade Federal do Espírito Santo
BR Mestrado em Física Centro de Ciências Exatas UFES Programa de Pós-Graduação em Física |
| Programa de Pós-Graduação: |
Não Informado pela instituição
|
| Departamento: |
Não Informado pela instituição
|
| País: |
Não Informado pela instituição
|
| Palavras-chave em Português: | |
| Link de acesso: | http://repositorio.ufes.br/handle/10/4768 |
Resumo: | In this work it ismade the experimental study of dynamic effects to the beginning of the fragile fracture, being used anapparatus that simulates atwo-dimensional crys-tallinestructure, in the which is possible to accomplish reversible experiments of frac-ture. The apparatus reproduces atomistic characteristics and it is formed quadrupolar magnets in the roleof unitary cells. That experiment is important because the obser-vation in-locoof the area at the beginning of the fracture it is not trivial. With the ob-jective of analyzing the dynamic effects in full detail until the beginning of the rupture, a system of image observation was developed in which was possible to obtain digital recordings with rates of the order of hundreds of pictures persecond. During the ex-ecution of the experiments, they were applied mechanical disturbances to the sys-tem. Each disturbance generated a harmonic oscillation that was filmed with the de-veloped equipment. The videos were analyzedpicture bypicture and with these data,graphs of the oscillation widthin function of the time were tracedand were observed picks and valleysthat decline exponentially. Starting from these graphs they were obtained the oscillation frequencies for each configuration of applied tension. This way it was obtained the equivalent constant of spring of the system. A peculiar beha-vior was also observed where a transienthappens before the first valleyis obtained. The mounted equipment was shownefficient for the purpose that was idealized and also for other applications involving mechanical oscillations and fracture dynamics, as the propagation of cracks, in materials of module of elasticity relatively low as the employed solid in this work |