Bonding Additively Manufactured PLA Materials: Effects of Joint Scarf Angle and Substrate Raster Orientation

The aim of this study is to investigate the effect of the scarf angle of the bonding region and the raster orientation of 3D printed substrates for the adhesive scarf joints made of additively manufactured Polylactic acid (PLA) adherends. In the first step, single PLA specimens were 3D printed using the fused filament fabrication (FFF) process in three different raster orientations of 0º, 45º, and 90º. Tensile and compression tests of them showed that the raster orientation of 90º gives the weakest results. Hence, in the second step, for the scarf joints, the PLA adherends were 3D printed in two different raster orientations of 0º and 45º. The joints were built with five different scarf angles of 15º, 30º, 45º, 60º, and 90º. The tensile and compression tests of all the specimens were conducted to determine the failure loads for different scarf angles and raster orientations. It is found that the endured load before rupture varies measurably as a function of the raster orientation of printed substrates and scarf angle of the joint, but differently for tensile and compression loadings. Eventually, the scarf angle for PLA scarf joints is determined which gives similar failure loads under both tension and compression loadings.