The effect of adhesive and adherend compliance on the failure of 3D-printed parts

The present study deals with the adhesive selection for extrusion-based 3D-printed parts. The compatibility of acrylate (AC), polyurethane (PU), methyl methacrylate (MM) and epoxy (EP) adhesives with polylactic acid (PLA), polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS), and acrylonitrile styrene acrylate (ASA) adherends was investigated. Tensile tests were conducted to provide enhanced knowledge on the failure behavior of these joints. Taguchi L16 orthogonal array and analysis of variance (ANOVA) were used to the design of experiment (DOE) and to identify the contribution of each parameter on the response, respectively. In addition, a closed-form solution of critical stress (peel and shear stresses) distributions along the bondline was used to gain a better insight into the failure mechanism of joints considered in this study. The ANOVA results showed that the effect of adhesive type is clearly the most important factor influencing the joint strength, followed by the adherend type. Statistically, the contribution of the adherend type (5.28%) is also important, but it is smaller than the contribution of the adhesive type (91.60%). The highest joint strength was obtained for PETG bonded with MM adhesive. In the case of PU, EP, and AC adhesives, the maximum load-carrying capacity was reached using PLA adherends. ASA showed the lowest joint strength for all adhesive types. This research provides comprehensive knowledge, allowing designers to select an appropriate adhesive for custom or industrial bonding applications without time-consuming surface treatments.