Instrumentação de um pendulo para ensaio de impacto Charpy

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

The conventional Impact Charpy Test allows for the determination of the total absorbed energy ( E IND. T ) for fracture of notched specimens. However, such energy is the result obtained by adding two important values : the absorbed energy due to the initiation of fracture ( E IND.I ), and the absorbed energy due to the propagation of this fracture. The aim of the present work has been to instrument the Impact Charpy Test, by means of extensometry and da ta acqui sition and digitalization techniques in order to evaluate the ( E IND.I and E IND. P ) components. After a brief review of the: i) Conventional impact Charpy test; ii) Metallic materiaIs fracture toughness theory ; iii) Dynamic analysis instrumentation basic requirements, a rig is described which four load cells were installed along the hammer tup , and employing two diferent methods: experimental and finite elements anaIysis, the best site for location of the foil strain-gages was determined. Afterwards, some impact tests were used to evaluate the performance of the instrumentatíon, using notched Charpy specimens in the following metaIIic aIIoys: i) High-strength aluminium; ii) Low-carbon ateeI; iii) Medium-carbon steel; iv) 300M steel. During the tests, it was observed that when the hammer s initial velocity decreased, in the high-s trength aIumini um, low-carbon stee I and 300M steel cases (2.0m/s or 3.0m/s), the maximum load values to initialize the specimens fracture, was significatively increased, and when total ductile fracture ocurred, those maximal loads resulted very similar to the expected loads. On the other hand, for increasing hammer s initial velocity (5.5m/s), and occurred brittle Charpy specimens fracture, the maximal load are toa much decreased

ASSUNTO(S)

materiais

ACESSO AO ARTIGO

Documentos Relacionados