Wedged mortise-tenon structure for fixed connections in additive manufacturing assemblies using fused filament fabrication

Abstract This study investigates the feasibility and performance of wedged mortise–tenon (M–T) joints as fixed connection mechanisms for assemblies fabricated through fused filament fabrication (FFF). By integrating a traditional self-locking joint concept into additive manufacturing, this work aims to provide an alternative to adhesives and mechanical fasteners. This bridges the gap from fabrication to the next-step assembly. An L9 orthogonal experimental design was applied to optimize four geometric parameters of the M–T joint, and the resulting configurations were evaluated through finite element simulation, tensile and flexural mechanical testing, and dimensional accuracy analysis using high-resolution 3D scanning. The optimized design achieved a tensile strength of 5.16 ± 0.66 MPa and flexural strength of 8.13 ± 0.37 MPa, outperforming adhesive-bonded joints in both strength and energy absorption, as evidenced by significantly higher tensile and flexural toughness derived from the area under the load–displacement curves. A dimensional deviation of only 0.026 mm confirmed high printing precision and assembly quality. These results demonstrate that wedged M–T joints offer reliable, strong, and sustainable fixed connections suitable for applications in furniture, automotive, aerospace, and medical device manufacturing. By eliminating the need for adhesives and mechanical fasteners, the proposed wedged M–T joint provides a scalable and sustainable assembly strategy for FFF-fabricated components, addressing build-volume limitations and enabling mechanically robust assemblies in structural and functional applications.