CHARACTERIZATION OF SOLID MODELS PRODUCED BY RAPID PROTOTYPING MACHINES

Abstract

Parts produced by 3-D printers were tested to determine the mechanical properties and failure modes. Since 3-D printed parts are built up layer-by-layer, they do not have the same properties in all directions. In order to determine the properties of the parts, tensile tests, compression tests, and bending tests were being performed per American Society of Testing and Materials standards. Additionally, a shear testing method is being developed that eliminates the need for specialized fixtures. A size effect was discovered where there is increased strength and modulus for parts with a large outer surface area to inner area ratio. Through the tensile, compression, and bending tests, it was discovered that vertically built specimens have about half the tensile and bending stress of horizontally built specimens. Additionally, the variation between strength values in tension and bending is greater for vertically built specimens than it is for horizontally built specimens. The initial build point has been identified as a stress concentration for 3-D printed parts. Understanding how 3-D-printed parts act under loads and how they fail is important to determining the applications for which the parts can be used. The information on these properties will allow manufacturers using 3-D printers to design better functional parts.