Temperature dependency comparison of ultrasonic wave propagation between injected and sintered thermoplastics

Abstract : Active touch localization based on a learning process of touch-disturbed broadband bending wave propagation in thin objects is used to transform any 3D surface into a multi-touch interface. Fast prototyping permits easy manufacturing of various 3D shapes that can be as quickly transformed into touch interfaces. The drawback is their weak mechanical stability with temperature. This paper details the temperature behavior differences between a sintered plastic such as polyamide polymer of type PA12 and raw injected Acrylonitrile-Butadiene-Styrene composite polymer (ABS), in particular how their physical parameters such as Young's modulus and Poisson's ratio are affected by temperature. Correlatively, longitudinal and transversal waves within injected and sintered plastics are investigated across a commercial temperature range of 10 °C to 70 °C. The internal grain structure in plastics obtained by laser sintering of powder makes these materials prone to stronger damping and clear non-linear temperature dependency of the shear wave velocity compared with injected plastics.