State Key Lab for Strength and Vibration of Mechanical Structures, International Center for Applied Mechanics, Department of Engineering Mechanics, Xi'an Jiaotong University, Xi'an, China.
Shanghai NewMed Medical Corporation, Shanghai, China.
Sci Adv. 2023 Mar 3;9(9):eade7375. doi: 10.1126/sciadv.ade7375.
Bovine pericardium (BP) has been used as leaflets of prosthetic heart valves. The leaflets are sutured on metallic stents and can survive 400 million flaps (~10-year life span), unaffected by the suture holes. This flaw-insensitive fatigue resistance is unmatched by synthetic leaflets. We show that the endurance strength of BP under cyclic stretch is insensitive to cuts as long as 1 centimeter, about two orders of magnitude longer than that of a thermoplastic polyurethane (TPU). The flaw-insensitive fatigue resistance of BP results from the high strength of collagen fibers and soft matrix between them. When BP is stretched, the soft matrix enables a collagen fiber to transmit tension over a long length. The energy in the long length dissipates when the fiber breaks. We demonstrate that a BP leaflet greatly outperforms a TPU leaflet. It is hoped that these findings will aid the development of soft materials for flaw-insensitive fatigue resistance.
牛心包（BP）已被用作人工心脏瓣膜的瓣叶。瓣叶缝合在金属支架上，可以承受 4 亿次瓣叶开合（~10 年的使用寿命），而不会受到缝线孔的影响。这种对缺陷不敏感的抗疲劳性是合成瓣叶无法比拟的。我们表明，BP 在循环拉伸下的耐力强度对长达 1 厘米的切口不敏感，比热塑性聚氨酯（TPU）长两个数量级。BP 的对缺陷不敏感的抗疲劳性源于其胶原纤维和它们之间的柔软基质的高强度。当 BP 被拉伸时，柔软的基质使胶原纤维能够在较长的长度上传递张力。当纤维断裂时，长距离的能量会耗散。我们证明了 BP 瓣叶大大优于 TPU 瓣叶。希望这些发现将有助于开发对缺陷不敏感的抗疲劳性的软材料。
