Ultrasound-Based Density Estimation of Composites Using Water-Air Interface

In this paper we present a new method to obtain the density of solid composites using ultrasound. The method exploits the relation between density and acoustic impedance and only requires the measurement of a reference signal form the interface water-air. Once made in a controlled environment, it can be used for any material, and does not require any additional measurement or set-up, so that with a simple calculus it can be used with automatic ultrasonic measurements to calculate the density and therefore elastic constants of the composite for its complete characterization. The method is applied to 3 different materials: two composites based on epoxy and polyester resins respectively with unknown final properties and a common methacrylate sample used as reference. Results show good concordance between obtained and expected results.