Anisotropic Behavior of Ultrasonic Waves in 3D Printed Materials

This study quantifies the anisotropic behavior of ultrasonic wave transmission for materials printed with three different 3D printers. As 3D printed materials become more prevalent in manufactured products, fully characterizing the physical properties of these materials become more important. This paper examines the longitudinal velocity of sound and acoustic impedance in two directions: orthogonal and parallel to the printed layers. Each of the 3D printed materials displayed slightly different transmission results. For PMMA like samples printed on a SLA printer waves travelled more quickly in the orthogonal direction than the parallel direction. For samples printed on an industrial FDM printer using ABS the opposite was true: the parallel direction was faster than the orthogonal. For samples printed on an entry level FDM printer with PLA there was no consistent pattern, instead there was a tight clustering of ultrasonic velocity in the parallel direction but substantial variation in the orthogonal direction. Overall the variation between the orthogonal and parallel directions was found to be less than 2% in all cases.