Design, Development, and Performance Evaluation of FDM-Based Fastening Techniques for Single-Lap Joints

This study illustrates the utilization of 3D-printed fastening mechanisms for the design and development of hybrid single-lap joints. For this purpose, a two-pronged methodology consisting of experimental and computational thrust was improvised for two different fastening mechanisms, namely thermomechanical fastening and in situ fastening. For the first technique, the fused deposition modeling (FDM) was employed to print fasteners using three different materials, namely polylactic acid (PLA), polyethylene terephthalate (PETG), and poly amide 6/carbon fiber (PA-6/CF). This technique consisted of two different printing sequences, i.e., horizontal, and vertical rivet configuration. The fasteners were then thermo-mechanically deformed to join aluminum sheets. The developed joints were characterized experimentally by tensile testing, where it was inferred that the load-carrying capability of each material differs with the printing sequence. Moreover, the failure modes were also linked with the printing sequence. In-situ fastening technique entailed joining of Al-acrylic sheets by printing the fasteners directly onto the sheets. A metallurgical bond was found between the acrylic sheet and PLA fasteners, thereby changing the failure mode from rivet failure to net sectioning of the acrylic sheet. Moreover, computational analyses were performed to validate the experimental tests and they were found to be in good agreement.