泡沫铝的低频内耗特征研究

INTERNAL FRICTION FEATURES OF FOAMED Al IN LOWER FREQUENCY

采用粉末冶金发泡法制备的泡沫铝试样，研究了室温下低频范围（００４—４Ｈｚ）泡沫铝的内耗与孔结构（孔隙率和孔径）、频率、振幅之间的关系．结果表明泡沫铝的内耗具有以下特征：孔径一定时，内耗随孔隙率的增加而增大；孔隙率一定时，内耗随孔径的减小而增大；在测量频率范围内，内耗与频率近似无关；小应变振幅时内耗随振幅的增大而增大，具有正常振幅效应．提出了泡沫铝的内耗产生机制，根据等效夹杂方法和钉扎位错内耗特点进行了理论分析。

Foamed aluminium (Al) specimens have been prepared by powder metallurgy foaming technique.At room temperature,variations of its internal friction vs porosity,frequency and strain amplitude were measured systematically.The results indicate that internal friction of foamed Al has such characteristics as follows.It increases with increasing porosity and with decreasing pore size.At lower frequencies,it is independent of frequency;it has a normal amplitude effect.The damping mechanism of foamed Al has been studied.According to the damping mechanism of foamed Al,the experimental results have been explained with some success.