Material damping estimation within low-, medium- and high-frequency ranges

When considering the dynamic response of mechanical systems, material damping is a main factor to account for. It largely affects phenomena at different time scales, from the transient response of the system, to its modal response, up to the acoustic wave propagation within the bulk and at the contact interfaces. Nevertheless, despite the key role of the material damping in the mechanical response, its estimation within a wide frequency range is still a challenge, when considering the existing technics. Moreover, the material damping varies largely with respect to frequency and the actual approaches for its estimation are limited within restricted frequency ranges. An approach for estimating the material damping within the overall frequency range does not exist in the literature. This paper proposes an approach where structural and acoustic technics are combined with an energy statistical approach, for identifying the trend of material damping within a larger frequency range. The approach is here applied to polycarbonate (PC) material. The results highlighted that the material damping in the low-medium frequency range (1Hz-several kHz) fits with the Rayleigh damping model. On the other hand, the damping in the higher frequency range (106 Hz) showed a stabilization with the increase of the frequency.