关键词: 增材制造, 管状纤维支架, 降维法, 解构设计, 简化打印

Abstract: The main challenges in preparing tubular fiber scaffolds using the melt electrowriting (MEW) technology lie in the lack of intuitive visualization for three-dimensional structural design and the need for independent control of multi-axis velocities during the printing process. These factors not only complicate the operation but may also introduce mechanical errors. Therefore, simplifying the design process and reducing operational complexity have become pivotal for enhancing the fabrication efficiency and quality of tubular fiber scaffolds. To address the current limitations in tubular printing, this paper proposes a dimension reduction design approach. With this approach, a series of preparatory tasks such as pattern design, path planning, and parameter optimization are all carried out on a 2D plane prior to printing. The actual printing operation is then performed solely on the tubular substrate. This approach aims to enhance the intuitiveness of tubular design and mitigate the difficulties associated with the printing process. When conducting pattern design on a 2D plane for tubular printing, there exists an inevitable limitation: tubular printing is constrained by its circumference in the R-axis (radial) direction. This necessitates special attention to the concept of "pivot point." The sum of the differences in Y-axis coordinate values between two consecutive pivot points must equate with the tube's circumference; otherwise, it may result in an incomplete fiber scaffold structure or fiber overlapping. To address this, an optimal printing path needs to be devised on the 2D plane, aiming to ensure the structural integrity of the fiber scaffold while minimizing redundant paths, as well as extraneous and repetitive paths outside the intended structure. Moreover, to fabricate fiber scaffolds with specific pore sizes and morphological structures, the mathematical relationships among various design parameters are explored on the 2D plane, offering clearer insights compared to direct design on a tubular surface. During the printing process, given the independent control of the X-axis and R-axis in tubular printing, the motion velocities of these two axes must be calculated separately, which complicates the operation and increases the likelihood of mechanical errors. To address this, the R-axis of the tubular structure is transformed into the Y-axis on the 2D plane. Both the X and Y axes can then be controlled by a single controller, sharing the same velocity. Additionally, by correctly setting the "Step per" parameter in the Mach3 software, the horizontal distance traveled during one full rotation of the Y-axis lead screw can be made exactly equal to the tube's circumference. Consequently, the pattern and code designed on the 2D plane can be directly applied to tubular fabrication, so as to significantly simplify the printing of tubular fiber scaffolds. To evaluate the effectiveness of the dimension reduction method, homogeneous and heterogeneous diamond-shaped structured fiber scaffolds with varying angles were printed, and the structure- property relationships between various fiber scaffold architectures and their mechanical behaviors are systematically investigated. This study aims to streamline the printing process of tubular fiber scaffolds, so as to enhance the intuitiveness of the design and reduce the complexity of printing operations. It offers a novel perspective and strategy for printing more intricate tubular fiber scaffold structures.

Key words: additive manufacturing, tubular fiber scaffolds, dimension reduction approach, deconstruction design, simplified printing