宏观孔对泡沫工业纯铝阻尼行为的影响

文章运用多功能内耗仪研究了宏观孔对空气加压渗流法制备的泡沫工业纯铝阻尼行为的影响。在室温低频率条件下测量了泡沫工业纯铝的内耗,实验结果表明泡沫工业纯铝的阻尼能力比致密工业纯铝的阻尼能力提高较大,前者内耗随着测量频率的增加而增加,同时也随应变振幅的增加而增大。运用TEM观察材料的微观结构,发现在晶界附近存在大量的位错亚结构。根据内耗测量和微观观察,讨论了泡沫工业纯铝中可能的阻尼机制,基于多孔弹性材料的平面波方程,理论计算得到了泡沫工业纯铝中内耗的表达式。

Effects of macroscopic pores on the damping behavior of foamed commercially pure aluminum

Experiments have been carried out to study the effects of macroscopic pores on the damping behavior of foamed commercially pure aluminum(FA).The damping characterization was conducted on a multifunction internal friction apparatus(MFIFA).The FA specimens were prepared by the air pressure infiltration process.The internal friction(IF) of the FA specimen was measured at low frequencies at room temperature.The measured IF shows that FA has a damping capacity which is enhanced in comparison with bulk commercially pure aluminum. The measured IF of the FA specimen increases as the porosity,frequency and strain amplitude increase,and it also increases with the decreasing of the macropore size.The microstructural analysis was performed using transmission electron microscopy(TEM).The TEM observations show that moderate density of dislocation substructures exist near the grain boundaries in the FA.In order to explain these phenomena,the possible operative damping mechanisms in the FA are discussed in light of IF measurements and microstructural observations,and an approximate expression for the IF is derived which is based on the equation of plane waves in elastic material with voids.