Structure design and stress analysis of 3D printing scaffold

• Main Authors: Chih-Chi Hsu, 許智齊
• Other Authors: 段維新
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/mu8kah

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 107 === The structure is crucial to the property of scaffold. Porous structure is needed for the transportation of nutrients and cells, which is important for the cell proliferation and vascularization. The cell proliferation can be accelerated with higher specific surface area. Besides, the mechanical property of the structure must be high enough to withstand the stress during surgery and subsequent motion after implant. Therefore, structure design is important to solve the contradiction between the porous structure and the mechanical property of scaffold. Twelve structures were designed and prepared with 3D printing using PLA material. Every structure has 50 % volume ratio and printed with 100 % infill density. The first group is pillar-structure (Z group), the second group is unit cell structure (BCC and FCC, U group) and the third group is the mixed structure of the former two groups with different mass ratio. The third group were named as BCC-Z and FCC-Z (U+Z group). The Z-axis and XY-axis compressive strength are measured for all structures (each structure has five samples for each direction, total for 120 samples). The result shows that porous structure with good compressive strength and high specific surface area can be achieved on mixed structure, FCC-Z. With the assistance of Finite Element Analysis (FEA), the relation between the stress distribution and the compressive strength of the structure can be explained. It allows us to realize the benefit and drawback of each design. The location and priority of fractures estimated by FEA stress analysis can correspond to the results in compressive testing. The Joint Square structure has much better structure sustainability and can bear more energy than Square in terms of the same strain. In addition, 3 structures made by calcium sulfate (CS) are used to prove the behavior found on PLA samples. The XY compressive testing is used to evaluate the weakness between 3D printing layers.