Abstract:

Low-sound-speed elastic materials are of great interest in a wide range of applications. The present research addresses the fabrication of a low-sound-speed elastic material in the form of a particulate composite. A polymeric matrix material is combined with highly compressible particulates (40-(mu)m diameter). At frequencies well below the monopole resonance of the particles, dilatational sound speeds as low as 400 m/s have been measured in experiments. The attenuation characteristics of the material are highly dependent upon frequency and may display transmissive or absorptive properties. The measured sound speeds and attenuations compare well with theoretical predictions for composites with relatively low volume fractions of particulates. Applications of these materials will also be discussed. [Work sponsored by the ARL:UT Independent Research and Development Program.]