Design and Evaluation of Interlocking Geometries for Multimaterial 3D Printing: A Combined Experimental and Numerical Approach

This work investigates the mechanical performance of various interlocking geometries for multimaterial joints produced via Fused Filament Fabrication (FFF). The study focuses on three joining strategies: dovetail, T-shaped, and wave interlocks applied to tensile test specimens based on ISO 527 standards. Each geometry was designed in multiple configurations, varying key geometric parameters such as dovetail angles and T-stem widths. Specimens were fabricated using PET-G and, for hybrid joints, a combination of PET-G and Nylon (PolyMide CoPa). Numerical simulations were conducted employing Representative Volume Elements (RVE) to account for anisotropic behavior and layer deposition patterns. Experimental tensile tests validated the simulation results and revealed consistent plastic deformation in the female part of mechanical interlocks. In wave specimens, where adhesion was the primary joining mechanism, strength increased significantly with surface area, while thermal post-processing (annealing) negatively affected mechanical performance. Overall, the findings confirm the critical role of geometry and surface interaction in joint strength and suggest that interlocking strategies can outperform adhesive-only solutions in multimaterial 3D printing. The results pave the way for more reliable, mechanically robust designs in polymer additive manufacturing.