Search

Additive manufacturing has thrived over the past decade due to its prominent potential of fast prototyping and complex components fabrication. Unlike conventional manufacturing that subtracts the desired products from the raw materials, 3D printing builds components upon layers, which may result in some degrees of uncertain shifts in terms of the material properties. While enhancing in-situ monitoring provides improving quality assurance during the process, reliable nondestructive methods are on-demand to provide the feedback of end products' elastic properties. A line-focus transducer system that utilizes ultrasound for material characterization is presented. The main hardware is a large aperture lens-less line-focus transducer with a theoretical central frequency of 10MHz, while a time-resolved method is adopted to avoid any mechanical scanning. This testing method is based on the propagation of surface and bulk acoustic waves and their relationship with mediums' elastic properties. The system is first validated by measuring conventionally produced metal bars and then applied to Stainless Steel 316L samples that are manufactured from Direct Metal Laser Sintering 3D printer. Sufficient signal processing and data analysis are conducted to predict samples' elastic properties' actual values, indicating a good match with the information on the official datasheet. This research aims to 1) introduce the fundamental of the piezoelectric effect, nondestructive testing methods, and additive manufacturing methods, 2) establish a solid understanding of the relationship between acoustic wave propagation and the stiffness constants. 3) build up a reliable line-focus transducer system with neat experiment and analysis procedure, 4) conclude the result and future expectations.