Abstract

The main goal of this experimental study is to obtain information about the elastic properties of some materials, specifically aluminum samples with regular geometry of polycristalline aluminum, through a non-invasive technique based on their resonance spectra. This technique is called "Resonant Ultrasound Spectroscopy" (RUS). In the non-linear regime, resonant frequencies of a sample are studied as a function of the excitation amplitude. As the excitation level increases, the elastic non-linearity is manifested by a shift in the resonance frequency as well as a deformation of the resonance. Using this method, previous researches have shown the relationship between the non-linear behavior of damaged materials and the level of this damage. We are exploring these effects in our samples, in search of a relationship between the dislocation density and the non-linear behavior, and we have observed clearly the shift and deformation of resonance in the non-linear regime. But a strong dependence of the elastic constants on the temperature induces a significant shift of resonance frequency in the linear regime. To obtain the non-linear parameter, the control and characterization of this effect has become another objective of our investigation.