Mono and bi‐material adhesive joints with additively manufactured continuous natural fiber‐reinforced biocomposite adherends

Abstract The scope of 3D printing is limited by its maximum printing area, necessitating joints for assembling larger structural elements. Natural fibers have been employed to reinforce printed materials, enhance their mechanical properties, and reduce polymer usage. However, the effects of these fibers on bonded joints, particularly in the context of continuous natural yarns, remain underexplored in the literature. This study investigates the mechanical behavior of 3D‐printed single‐lap joints (SLJ) with biocomposite adherends, using Fused Filament Fabrication (FFF). Continuous Jute Fiber Reinforced Polymer (JFRP) and Polylactic Acid (PLA) were used to fabricate the adherends. Mechanical characterization, including surface roughness analysis and single‐lap shear tests, was performed on PLA‐PLA, JFRP‐JFRP, JFRP‐steel, and JFRP‐wood joints. Results show that the addition of continuous jute fibers in mono‐material joints increased the failure load by 66.53% compared to neat PLA‐PLA joints, due to a 47.20% increase in surface roughness. Jute Fiber Reinforced Polymer‐wood joints demonstrated the best performance, achieving a failure load of 2543.76N, 56.85% higher than JFRP‐JFRP joints, indicating their potential for mixed‐material, sustainable structures. Analytical models were applied to assess the load distribution along the adhesive. Highlights Continuous natural yarn improves composite behavior, reducing brittle failure. Natural fibers enhance failure load and mode toughness of bonded joints. Jute yarn in joints raises SLJ failure load by 66.53%, enhancing contact area. Analyses of 3D‐printed parts with natural fibers bonded to wood and steel. Bi‐material joints show better results due to higher rigidity.