https://amt.sbu.ac.ir/ Additive Manufacturing Technology en daily 1 Mon, 13 Jul 2026 00:00:00 +0330 Mon, 13 Jul 2026 00:00:00 +0330 https://amt.sbu.ac.ir/article_107239.html In recent years, multistable metastructures have emerged as a central focus in research on smart materials and reconfigurable structures. These structures, with their ability to transition controllably among multiple stable states, enable the design of lightweight, adaptable, and programmably reconfigurable systems. Advances in additive manufacturing, particularly Fused Filament Fabrication (FFF) 3D printing, have opened new pathways for precise engineering of multistable behavior and for controlling geometric parameters, material arrangements, and residual stresses. The primary approaches to achieving multistability include the design of compliant mechanisms, the use of specific cellular arrangements, and integrated fabrication via 3D printing. These strategies facilitate large deformations, sequences of snap-through events, and controlled energy storage. The influence of additive manufacturing parameters, such as layer orientation and thickness, infill density, and thermal conditions, on the number of stable states and energy well depths has been demonstrated. This review article discusses design principles, activation mechanisms, the role of cellular architecture, and the impact of printing process parameters on the development of multistable metastructures, providing a comprehensive framework for understanding and advancing this field. https://amt.sbu.ac.ir/article_107240.html One of the significant challenges in the 3D printing of multilayered cylindrical composite parts with different angle plies, such as tubes, lies in the limitations in controlling the layering angle and the orientation of reinforcing fibers. In this study, with the aim of producing composite tubes with various layup configurations, a novel method is proposed in which a fourth rotational axis is added to a fused deposition modeling (FDM) 3D printer to enable the adjustment and precise control of the layering angle during the printing process. Following the design and implementation of the rotational axis to the FDM 3D printer, tubes with a length of 120 mm and an internal diameter of 60 mm were fabricated using PLA matrix and continuous glass fiber reinforcement. The tubes were printed with two layups of [+45, -45]3 and [+55, -55]3. The specimens were then subjected to quasi-static axial compression loading. The loading was applied at three levels: 1) loading until the initial failure, 2) loading until a semi-compressed state (30 mm compressive displacement), and 3) loading until full compression (100 mm compressive displacement). The results did not show a significant difference in the ultimate strength of the tubes, while the stiffness of the [+55, -55]3 tubes was 65% higher than that of [+45, -45]3 tubes. https://amt.sbu.ac.ir/article_107251.html The Fused Deposition Modeling (FDM) method is one of the most common techniques for producing polymer parts via 3D printing. However, its widespread adoption in critical, load-bearing applications has been constrained by the inherently low mechanical properties of standard printed polymers. To address this limitation, this study modified the printing mechanism of a commercial FDM printer to enable the simultaneous deposition of a polymer matrix and continuous glass fibers, thereby creating composite parts. The research specifically investigated the effects of two key parameters: nozzle diameter and specimen layup. The fabricated composite specimens were then subjected to quasi-static tensile testing. The results conclusively demonstrated that the integration of continuous fibers into the polymer matrix led to substantial enhancements in mechanical performance. This was evidenced by a remarkable increase in both the tensile strength and the elastic modulus of the printed parts, confirming the potential of this modified process for producing structurally robust components.