Investigation of process variation effects via a homogeneous 3-dimensional tensile test coupon in polyjet 3D additive printing

PolyJet printing technology is one of few additive manufacturing (AM) techniques capable of making the monolithic, multi-material structure. This paper investigates the Polyjet process variation effects that leads to differences in properties based on how it is built by designing a homogenized 3-dimensional tensile test coupon. Traditional ASTM D638 tensile test coupon’s limitation is that one direction is thinner than the other two directions, which may not account for non-uniformity in material deposition in all three directions during printing. Firstly, these test coupons do not represent the real-world material behavior, and secondly, the effect of normal strain, which is a compressive strain in thinner directions, is not effectively captured. To avoid these limitations of the traditional specimen, a homogeneous 3-dimensional tensile test configuration is designed to keep the same cross-section’s aspect ratio to form uniform material deposition. Results from tensile behavior of both traditional and homogeneous 3-Dimensional specimen are discussed. Study findings provide insight on the limitation of traditional test coupon and careful evaluations of process variation effect in Polyjet printing. The fracture surface of both PolyJet printed failed specimen are also examined to provide insight into failure characteristic. Findings aid in further understanding the process dependent properties capturing three-dimensional effects of Polyjet printing process.