The Finite Element Method In Biomedical Engineering Applications

Finite Element Method (FEM) has been widely adopted and substantially developed in various fields of engineering since its birth in the middle of 20th century. Large-scale general applications have made FEM a useful tool in biomedical engineering with their powerful functions, easy manipulation, reliable results and high efficiency. We will give specific introduction of the application of FEM in biomedical engineering with two major examples: analysis of 2D heat transfer model of human lower leg, and analysis of 3D hemodynamic models of two intracranial aneurysms based on actual medical images.After introduction on main heat transfer patterns, generally-used heat transfer models and measuring methods of thermal properties of biological tissue, we established a simplified 2D heat transfer model based on the cross section of human lower leg, and divided it into bone layer, deep muscle layer, outer muscle layer and skin layer according to their significant differences in heat transfer. We analyzed the effects of blood perfusion rate, metabolic heat generation rate, environmental temperature and air convection coefficient on heat transfer. And the results showed that the effects of metabolic heat generation rate and air convection coefficient on tissue temperature distribution are relatively weak, while the effects of blood perfusion rate and environmental temperature on tissue temperature distribution are becoming weaker when they gradually increases. We also analyzed the model while ignoring the effects of parallel countercurrent vessel pairs, and results showed that they play key roles in heat transfer in tissues.We accurately reconstructed 3D geometric models of the intracranial aneurysms based on original 3DRA images of two patients, and then established hemodynamic models on assumptions that blood is Newtonian fluid and blood vessel walls are rigid. Results showed that the points with the maximum of wall sheer stress (WSS) exist at the neck of the aneurysms, which is a result of the large gradient of blood velocity due to the constant impact on the vessel wall. We also found that WSS of aneurysms is very small and barely changes, while the parent arteries have dramatic change in WSS. which is an important factor in the development and rupture of aneurysms.