| The vibration properties of the pure Al plate and pure Cu plate, 12 ㎜ wide and 164∼254 ㎜ long, were investigated by cantilever beam and RFDA to get the following results. (1) The results by cantilever beam method and RFDA show that the resonance frequency decreases as the specimen length increases or the thickness decreases. (2) When measuring the vibration by the cantilever beam method, the vibration damping coefficients are stable at the specimen with 184 ㎜ or higher length. (3) When measuring the vibration damping coefficient by the cantilever beam method, the mean vibration damping ratio of Al specimen 1.6∼0.8 ㎜ thick is 3.1×10^(-2) and 4.0×10^(-2) in Cu specimen of 2.0∼1.2 ㎜ (4) When measuring the vibration damping properties by the RFDA, vibration damping coefficients are similar regardless of the length and thickness of a specimen and the mean vibration damping ratios of Al and Cu were 2.1×10^(-2) and 2.7×10^(-2), respectively. (5) As a result of (3) and (4), The relationship, between the vibration damping ratio measured by the cantilever beam method and it by the RFDA was founded as g_s=(δ_o/δ_r)×(1/1.5). |
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