Towards standardizing the preparation of test specimens made with material extrusion: Review of current techniques for tensile testing

Abstract

Researchers and industries rely heavily on standardized testing methods to ensure products are designed and manufactured with high quality. With increasing use of additive manufacturing processes, such as material extrusion (MEX), there is a significant gap in material testing standards tailored for such components, and a lack of guidance on preparing appropriate test specimens with mesostructures that best represent the final part being analyzed. This paper aims to support the standardization of MEX material testing by reviewing the current methods used for preparing test specimens for tensile testing and proposing guidelines for implementation in a new standard. The need for standardization of MEX specimen preparation is addressed by analyzing the effects of slicing parameters on resulting tensile properties of the specimen. It is suggested that a standard should acknowledge these parameters, in addition to specimen geometry, toolpath optimization, printer and material specifications, so that they are appropriately selected for the test specimen by regarding the final part structure. Consideration of the proposed guidelines in a standardized method may enable comparisons between published results and support the development of MEX technology for use in advanced applications. • Material testing standards are incomplete for specimens made by material extrusion. • Test specimen preparation procedures found in literature are inconsistent. • Process parameters greatly influence tensile strength and stiffness. • Guidelines for a standard test specimen preparation procedure are proposed.