Fluid Solid Interaction Analysis Of The Bioprosthetic Heart Valve Based On FLUENT And LS-DYNA

The heart is the body's vital organs,heart valves event of disease would endanger human life.Replacement of the valve is still the main treatment of valvular heart disease.Bioprosthetic heart valve(BHV)have good mechanical properties,has gradually become the preferred valve in replacement surgery,but there are still have problems in durability,mainly in the valve material fatigue and destruction.Coupling process of BHV and blood was analyzed by the computational fluid mechanics,and deformation characteristics and stress distributions could be obtained on leaflets which have important theoretical significance and reference value on the research of the reason of valve damage and calcification.According to the characteristics of the primary heart valve,the elastic structure valve model and the incompressible viscous fluid model were established.The finite volume method(FVM)and Arbitrary Lagrange-Euler(ALE)method were used to derive the blood and leaflet of fluid-structure interaction(FSI)equation,and then use the one-way and two-way fluid-structure interaction software FLUENT and LS-DYNA to analysis the corresponding coupling process of leaflets and blood software simulation,the valve leaf deformation,surface stress and open area change situation,and to compare the influence of Poisson ratio and elastic modulus of two kinds of analysis results of the fluid solid coupling.Through the pulsatile flow test of similar simulation model of the BHV,deformation of valve leaf through test results and the opening area changes and the simulation results are compared,and results of two methods of coupling analysis are evaluated in accuracy.By comparing the two kinds of coupling analysis,the results of pulsatile flow test can be drawn:the two-way fluid-structure interaction analysis and pulsating flow test results more close to the leaflets in the process of opening area of the opening shape is approximated by triangle became round,and the opening speed in the early stage after the fast slow down gradually,and in 45ms the leaflets were fully open.The results of FLUENT one-way fluid-structure interaction analysis are similar to the pulsatile flow test results when the deformation of the flap is small.Therefore,it is more appropriate to use the LS-DYNA method to analyze the coupling of the valve and the blood flow.According to the results of two-way fluid-structure interaction analysis by using LS-DYNA,the equivalent stress and shear stress of the flap are mainly concentrated at the junction between the flap and the free edge.Poisson's ratio has little effect on the deformation and effective opening area,but the surface stress will decrease with the increase of Poisson's ratio.When the Poisson's ratio is 0.45,the mechanical property of the leaf is the best.The elastic modulus will increase leaflet deformation and effective opening area is reduced,the equivalent stress and maximum shear stress decreases with the increase of the elastic modulus,the maximum principal stress increases with the increase of the elastic modulus,elastic modulus is 4Mpa,the mechanical properties of the leaflets of the best.The treatment of petal is considered to obtain a larger Poisson's ratio and smaller elastic modulus.In this paper,the coupling process of the BHV and blood was analyzed by one-way and two-way fluid-structure interaction by using FLUENT and LS-DYNA,and the pulsatile flow test was carried out to get leaflet deformation and surface stress distribution.By contrast,the ALE two-way fluid-structure interaction analysis results and the test results are closer and more real to the results,and has important reference value on the mechanical properties evaluation of BHV,and also provide the basis for the optimization design of BHV.