Effects of process parameters and geometry on dimensional accuracy and surface quality of thin strut heart valve frames manufactured by laser powder bed fusion
Effects of process parameters and geometry on dimensional accuracy and surface quality of thin strut heart valve frames manufactured by laser powder bed fusion
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DOI：
10.21203/rs.3.rs-1271909/v1
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
Xiao Zhao;Anqi Liang;M. Bellin;N. Bressloff
中科院分区：
文献类型：
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作者：
Xiao Zhao;Anqi Liang;M. Bellin;N. Bressloff
激光粉末床熔融（LPBF）是最流行的金属增材制造技术之一，已在航空航天和生物医学设备等高价值领域得到应用。最近关于支架LPBF的一些研究已经证明了其在薄支柱结构（包括心脏瓣膜框架）中制造的可行性，如用于治疗严重主动脉瓣狭窄的经导管主动脉瓣植入术（TAVI）。激光切割TAVI瓣架的现有技术方法限制了通过增材制造实现的新概念的范围。然而，LPBF零件的表面质量和尺寸精度低于激光切割。为了开始开发新的TAVI概念，Edwards Lifesciences基于SAPIEN 3瓣架研究了通过LPBF制造薄瓣架的可行性。在本研究中，已成功制造了支柱尺寸为0.3 mm至0.5 mm的简化支架。系统地研究了支撑尺寸、支撑角度、激光功率和扫描速度等工艺参数对成形尺寸精度和表面质量的影响。此外，还制造了代表性SAPIEN 3瓣架，并通过高分辨率X射线扫描进行了评估。SAPIEN 3瓣架获得了良好的总体尺寸精度和低孔隙率。然而，发现倾斜支柱具有相对低的尺寸精度和差的表面质量。
Laser powder bed fusion (LPBF) is one of the most popular metal additive manufacturing technologies, which has found its applications in high-value sectors such as aerospace and biomedical devices. Some recent studies on the LPBF of stents have demonstrated its feasibility in the fabrication in thin strut structures including heart valve frames, as used in transcatheter aortic valve implantation (TAVI) for the treatment of severe aortic stenosis. The state of the art method of laser cutting TAVI frame limits the scope for novel concepts which are made possible by additive manufacturing. However, the surface quality and dimensional accuracy of LPBF parts are lower than that produced by laser cutting. To start the development of new TAVI concepts, the feasibility of manufacturing thin frames by LPBF has been investigated based the SAPIEN 3 frame by Edwards Lifesciences. In this study, simplified frames with strut size from 0.3 mm to 0.5 mm have been successfully manufactured. The effects of strut size, strut angle, laser power and scan speed on the dimensional accuracy and surface quality were systemically studied. In addition, a representative SAPIEN 3 frame was manufactured and assessed with high resolution X-ray scans. Good overall dimensional accuracy and low porosity was obtained for the SAPIEN 3 frame. However, inclined struts were found to have relatively low dimensional accuracy and poor surface quality.