The present study aimed to design and optimize thoracic aorta stent grafts (SGs) based on the influence of geometric parameters on flexibility and durability. Five geometric parameters were selected, including strut height, strut number, strut radius, wire diameter, and graft thickness. Subsequently, 16 finite element (FE) models were established with an orthogonal design consisting of five factors and four levels. The influences of a single factor and all the geometric parameters' influence magnitude on the device flexibility were then determined. The results showed that all the other parameters had an opposite effect on global and local flexibility except for the wire diameter. The graft thickness exhibited the most remarkable impact on the global flexibility of SGs, while the strut radius influenced flexibility slightly. However, for the local flexibility analysis, the graft thickness became the least significant factor, and the wire diameter exerted the most significant influence. The SG with better global flexibility can be guided easily in the tortuous vessels, and better local flexibility improves the sealing effect between the graft and aortic arch. In conclusion, this study's results indicated that these geometric parameters exerted different influences on flexibility and durability, providing a strategy for designing thoracic aorta SGs, especially for the thoracic aortic arch diseases.
Keywords: finite element method; flexibility; geometric parameters; orthogonal test; thoracic aorta.