泡沫Al阻尼性能研究

STUDY ON THE DAMPING CHARACTERISTICS OF FOAMED ALUMINUM

通过测定不同频率、温度和应变振幅下的内耗，研究了泡沫Ａｌ的阻尼性能．泡沫Ａｌ组织中孔洞对阻尼的贡献是使背景内耗特别是高温背景内耗增加．泡沫Ａｌ阻尼的另一个特点是较为显著的振幅效应，这一效应随孔径减小而变得更加突出，由于泡沫Ａｌ所特有的非均质性孔洞组态和高密度缺陷，应力应变分布极不均匀，加上外部应力的干扰，造成缺陷密度增加，因此缺陷阻尼是主要的阻尼机制．

Abstract Internal friction measurements have been performed at the different frequencies, temperatures and strain amplitudes to examine the damping characteristics of foamed aluminum. It is found that the pores contribute to the damping by raising the internal friction background, particularly the high temperature one. The other significant feature is that the internal friction is strain amplitude dependent, which becomes more obvious as the pore size decreases. There are inhomogeneous pores and high density of defects in the structure, leading to nonuniformly distributed stress and strain. This state will be intensified under the disturbance of applied load, making the defect density increase. The defect effects are therefore responsible for the damping characteristics of foamed aluminum.