A study on additive manufacturing build parameters as bonded joint design factors

This work explores the influence of Additive Manufacturing (AM) parameters on the Mode I fracture toughness of polymer bonded joints. The motivation is that realizing AM parts to be later assembled can be convenient from the manufacturing standpoint and adhesive bonding avoids distortion and material modification due to heat while welding or the use of fasteners. PLA and ABS joints were tested and three different printing parameters (extruder temperature, printing speed and layer thickness) were selected to evaluate their influence on roughness, wettability and tensile behaviour of the adherends. A full-factorial Design of Experiment was chosen to study roughness and wettability because of the short sample manufacturing and measurement time, while a Taguchi L9 orthogonal array was selected for the tensile testsr to save manufacturing and testing time. The significance and the mutual interactions of printing parameters were identified by analysis of variance. Combinations yielding maximum and minimum values of the output, respectively, were used to produce adherends for Double Cantilever Beam (DCB) joints and evaluate the effect on Mode I fracture toughness, demonstrating that process parameters do have an effect on fracture toughness and that an optimum value can be found by simply operating on the AM setup.