Shôsuke Imoto1 and Genjirô Mima1
1Faculty of Engineering, Osaka University,
The internal friction and its amplitude dependence were measured with copper specimens. The oxygen-free copper specimens which we used were impure and its internal friction was low, but the oxygen-bearing copper specimens which had been forged had higher internal friction and a maximum in damping appeared with increasing the amplitude. The internal friction of a specimen of tough pitch copper as cast was low in spite of the presence of oxygen, but on annealing it at a high temperature the internal friction grew and the maximum appeared. These results were explained by assuming the oxide forming action of oxygen with other impurities.
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