CN104758093B - A kind of analysis method optimized based on ANSYS/Workbench artificial heart valve film dynamic performance - Google Patents

Abstract

The invention discloses a kind of analysis method optimized based on ANSYS/Workbench artificial heart valve film dynamic performance, this method is with heart lobe hydrodynamics as foundation, illustrate the theory that fluid domain (blood) intercouples with solid domain (Cardiac valve prosthesis), by building the indirect fluid-solid coupling model of biovalve, carry out the wind-structure interaction of biovalve.It is configured as prototype with human body natural heart lobe, leaflet reference profile in conjunction with current research field, selecting Surface of Sphere, the face of cylinder, the paraboloid of revolution and four kinds of surface of revolutions of ellipsoid is the biovalve prototype plane of reference, the invention provides and analyzes the analysis method that different biovalve lobe type mechanical property is good and bad.

Description

A kind of based on dividing that ANSYS/Workbench artificial heart valve film dynamic performance optimizes Analysis method

Technical field

The present invention relates to a kind of analysis side optimized based on ANSYS/Workbench artificial heart valve film dynamic performance Method.

Background technology

The pathological changes of heart lobe valve will damage hemodynamic performance, affect the blood circulation of human normal.Since 1960 adopt After successful surgery with artificial valve replacement performance not conscience lobe, existing up to ten million patient has carried out displacement cardiac valve procedure, from And extend patient's life-span.Owing to biovalve has preferable hemodynamics performance, it is not necessary to take anticoagulant all the life And the advantage such as the probability of thromboembolism is low, it is used widely in clinic.For many years, research worker are devoted to grind always The heart lobe that performance processed is the most excellent, but the function of bioprosthetic valve there are still bigger difference with native heart valve at present.Patient puts Intimate after lobe, owing to the structure degradation of biovalve makes heart lobe damage thus reduce valvular service life.Stress is concentrated It it is the one of the main reasons of biovalve structure degradation.

Therefore, analyze the coupled problem between blood and biovalve, optimize the configuration of biovalve, the detailed understanding heart The stress distribution etc. of lobe, this has highly important reason to the optimization design of the understanding reason of valve failure, valve geometric parameter Value and realistic meaning.

Summary of the invention

The present invention is to solve the problems referred to above, it is proposed that a kind of based on ANSYS/Workbench Cardiac valve prosthesis mechanics The analysis method that performance optimizes, this method, with heart lobe hydrodynamics as foundation, illustrates fluid domain (blood) and solid domain (people Work cardiac valve) theory that intercouples, by building the indirect fluid-solid coupling model of biovalve, carry out biovalve Wind-structure interaction.It is configured as prototype with human body natural heart lobe, in conjunction with the leaflet reference profile of current research field, selects circle Sphere, the face of cylinder, the paraboloid of revolution and four kinds of surface of revolutions of ellipsoid are the biovalve prototype plane of reference, the invention provides point The analysis method that the different biovalve lobe type mechanical property of analysis is good and bad.

To achieve these goals, the present invention adopts the following technical scheme that

A kind of analysis method optimized based on ANSYS/Workbench artificial heart valve film dynamic performance, including following step Rapid:

(1) intercouple with solid domain based on fluid domain, build fluid governing equation, solid governing equation, determine that stream is solid Coupled interface, calculates and acts on the power in valve leaflets；

(2) based on ANSYS/Workbench, the interaction between blood and three leaflets is carried out fluid structurecoupling dynamic Mechanics property analysis；

(3) with Surface of Sphere, the face of cylinder, the paraboloid of revolution and four kinds of surface of revolutions of ellipsoid for biovalve prototype reference Face, analyzes the mechanical property of different biovalve configuration, and contrasts.

In described step (1), because the most there is not lap in solid domain and fluid domain, therefore can only leaflet with Fluid structure interaction occurs on the interface of blood, because the ability that valve itself does not actively shrink, the opening and closing of leaflet is complete Depending on blood and the flexible traction force to leaflet of annulus, the theory that fluid domain and solid domain intercouple illustrates at coupling surface The power of upper fluid node acts on solid node, thus promotes the motion of solid.

In described step (1), the method building fluid governing equation is:

Blood is incompressible liquid, therefore the fluid domain of blood uses incompressible Navier Stokes fluid control Equation processed describes:^:

$\stackrel{\→}{\▿}\·\stackrel{\→}{u}=0$

$\mathrm{\ρ}(\frac{\∂\stackrel{\→}{u}}{\∂t}+\stackrel{\→}{u}\·\stackrel{\→}{\▿}\stackrel{\→}{u})=-\stackrel{\→}{\▿}p+\mathrm{\μ}{\▿}^2\stackrel{\→}{u}+\stackrel{\→}{F}$

In above formulaFor the velocity vector of any point in blood；ρ is density of blood；μ is the viscosity of blood；P is the pressure of blood Power；F is the body force (human body is supplied to blood) acting on blood；T is the time；Gradient operator for current configuration；

In order to simplify calculating, above formula is carried out nondimensionalization:

$\stackrel{\→}{\▿}\·\stackrel{\→}{u}=0$

$\frac{\∂\stackrel{\→}{u}}{\∂t}+\stackrel{\→}{u}\·\stackrel{\→}{\▿}\stackrel{\→}{u}=-\stackrel{\→}{\▿}p+\frac{1}{\mathrm{Re}}{\▿}^2\stackrel{\→}{u}+\stackrel{\→}{f}$

In above formula, Re is Reynolds number, Re=ρ_fUL/ η, U are the flow velocity of fluid；ρ_fFor fluid density；η is viscosity coefficient, and L is Characteristic length, f is the body force that human body acts on blood.

In described step (1), build solid governing equation method particularly includes:

What solid governing equation described is the deformation of solid under hydrokinetic effect, for the problem of blood Yu valve, Definition solid i.e. valve is nonlinear elastic material, the stress equation of valve:

$\frac{{\mathrm{\ρ}}_s}{{\mathrm{\ρ}}_f}\stackrel{\stackrel{\·\·}{\→}}{x}-\mathrm{Div}{\underset{\‾}{\mathrm{\σ}}}_s=\stackrel{\→}{b}$

ρ in above formula_sDensity for solid；ρ_fFor density of blood；Acceleration for solid；σ _sStress tensor for structure；For acting on the body force of solid.

In described step (1), determine that the method at fluid structurecoupling interface is:

Fluid is coupling surface Γ with the interaction part of solid_sf, coupling surface has speed seriality and surface force is continuous Property, therefore, the position of coupling surface:

In above formulaFor horizontal domain set domain,Displacement for leaflet.

The speed of coupling surface and acceleration:

${\stackrel{\→}{u}}_f{|}_{{\mathrm{\Γ}}_{\mathrm{sf}}}={\stackrel{\→}{x}}_s{|}_{{\mathrm{\Γ}}_{\mathrm{sf}}}$

In above formulaFor the speed of blood on coupling surface；For the displacement of leaflet on coupling surface,

${\stackrel{\→}{a}}_f{|}_{{\mathrm{\Γ}}_{\mathrm{sf}}}={\stackrel{\stackrel{\·\·}{\→}}{x}}_s{|}_{{\mathrm{\Γ}}_{\mathrm{sf}}}$

In above formulaFor the acceleration of blood on coupling surface,

${\underset{\‾}{\mathrm{\σ}}}_s{|}_{{\mathrm{\Γ}}_{\mathrm{sf}}}\·\stackrel{\→}{n}={\underset{\‾}{\mathrm{\σ}}}_f{|}_{{\mathrm{\Γ}}_{\mathrm{sf}}}\stackrel{\→}{n}$

In above formula,σFor stress tensor；For the local approach vector of coupling surface, subscript s and f represent solid and fluid respectively.

In described step (2), concrete grammar includes:

A. use PRO/E that biovalve leaflet and arterial wall are carried out d solid modeling；

B. ANSYS/Workbench program is used, according to the ess-strain of the fresh bio valvular tissue material measured The data of relation curve define valvular material；

C. biovalve leaflet and arterial wall model imported Workbench program with the form of IGES and carry out grid and draw Point, obtain fluid structurecoupling dynamic mechanical analysis FEM (finite element) model；

D. the parameter provided according to medical research applies fluid structurecoupling boundary condition；

E. by indirect fluid-solid coupling analytical calculation, stress distribution situation and the blood of Cardiac valve prosthesis leaflet are drawn The motion conditions of liquid.

Described step (3) method particularly includes:

A. four kinds of leaflet profiles are analyzed all in accordance with the step of A, B, C, D in step (2)；

B. by indirect fluid-solid coupling analytical calculation, draw Cardiac valve prosthesis leaflet maximum principal stress, etc. effect Power and the distribution situation of the maximum shear stress, and four kinds of valve configuration mechanical properties are analyzed contrast.

The invention have the benefit that the present invention with heart lobe Hydrodynamics Theory as foundation, utilize finite element software for Biovalve carries out fluid structurecoupling dynamics simulation, draws pressure curve and the rate curve of blood, also biovalve lobe The stress distribution of leaf.Carrying out maximum principal stress, equivalent stress and maximum shear for four kinds of leaflet configurations of biovalve should The analysis contrast of power distributed areas and size, thus conclude that stress concentration phenomenon be mainly distributed on the combination limit of leaflet with Sew up region and the central area, combination limit of leaflet that border is intersected.Face of cylinder mechanical property in every respect is the most poor, and revolves Turning parabola, Surface of Sphere and ellipsoid and have respective advantage at different aspect, this is that the biovalve developing function admirable carries Supply foundation.

Accompanying drawing explanation

Fig. 1 (a) is Surface of Sphere type leaflet moulding schematic diagram；

Fig. 1 (b) is Surface of Sphere type leaflet moulding schematic diagram；

Fig. 1 (c) is Surface of Sphere type leaflet moulding schematic diagram；

Fig. 2 (a) is face of cylinder type leaflet moulding schematic diagram；

Fig. 2 (b) is face of cylinder type leaflet moulding schematic diagram；

Fig. 2 (c) is face of cylinder type leaflet moulding schematic diagram；

Fig. 3 (a) is paraboloid of revolution type leaflet moulding schematic diagram；

Fig. 3 (b) is paraboloid of revolution type leaflet moulding schematic diagram；

Fig. 3 (c) is paraboloid of revolution type leaflet moulding schematic diagram；

Fig. 4 (a) is ellipsoid type leaflet moulding schematic diagram；

Fig. 4 (b) is ellipsoid type leaflet moulding schematic diagram；

Fig. 4 (c) is ellipsoid type leaflet moulding schematic diagram；

Fig. 5 (a) is leaflet lobe hole modeling parameters schematic diagram；

Fig. 5 (b) is leaflet lobe hole physical model schematic diagram；

Fig. 6 (a) is biovalve fluid structurecoupling physical model schematic diagram；

Fig. 6 (b) is biovalve indirect fluid-solid coupling model schematic；

Fig. 7 is the stress strain curve figure of biological valvular tissue material；

Fig. 8 is Blood Model entrance, outlet and the definition of fluid structurecoupling face；

Fig. 9 is the definition of leaflet boundary condition；

Figure 10 is the blood velocity profile of sampled point；

Figure 11 is the blood pressure curve chart of sampled point；

Figure 12 is the time dependent Stress Map of valve；

Four kinds of profile leaflet equivalent stress cloud atlas when Figure 13 (a) is 0.022s；

Four kinds of profile leaflet equivalent stress cloud atlas when Figure 13 (b) is 0.044s；

Four kinds of profile leaflet equivalent stress cloud atlas when Figure 13 (c) is 0.067s；

Four kinds of profile leaflet equivalent stress cloud atlas when Figure 13 (d) is 0.089s；

Four kinds of profile leaflet maximum principal stress Stress Map when Figure 14 (a) is 0.2222s；

Four kinds of profile leaflet maximum principal stress Stress Map when Figure 14 (b) is 0.4444s；

Four kinds of profile leaflet maximum principal stress Stress Map when Figure 14 (c) is 0.6667s；

Four kinds of profile leaflet maximum principal stress Stress Map when Figure 14 (d) is 0.8889s；

Four kinds of profile leaflet the maximum shear stress cloud atlas when Figure 15 (a) is 0.2222s；

Four kinds of profile leaflet the maximum shear stress cloud atlas when Figure 15 (b) is 0.4444s；

Four kinds of profile leaflet the maximum shear stress cloud atlas when Figure 15 (c) is 0.6667s；

Four kinds of profile leaflet the maximum shear stress cloud atlas when Figure 15 (d) is 0.8889s.

Detailed description of the invention:

The invention will be further described with embodiment below in conjunction with the accompanying drawings.

Biovalve fluid structurecoupling mechanics property analysis based on ANSYS, step is as follows:

A.1. the Geometric Modeling of (1) biovalve leaflet

During the leaflet of biovalve models, we are with the acquiescence Cartesian coordinate initial point of Pro/E software for building Mould initial point O, creates according to the geometric equation of each surface of revolution (Surface of Sphere, the face of cylinder, the paraboloid of revolution and ellipsoid) and rotates song Face.Be parallel to Z axis (13,0, z) straight line is rotary shaft, makees the taper seat of minimum point B of surface of revolution, the half of taper seat Apex angle α is 3 °.Taper seat and four kinds of surface of revolutions intersect, and draw intersection.XOZ plane is inclined for axis with the rotary shaft of taper seat TurnThe peak that the plane formed and the intersection point A and A ' of intersection are monolithic leaflet.Intersection is single with the intersection points B of Z axis The minimum point of sheet leaflet.Surface of revolution and the minimum point that intersection point is monolithic leaflet free margins of circular cone axis.AC and the angle of X-axis It is the angle β of leaflet free margins and joint portion plane.And the difference of the Z coordinate of A point and B point is the height H of leaflet or lobe frame. After the parametric modeling of biovalve, above-mentioned geometric parameter can obtain.

1, Surface of Sphere is as the parameter model of the plane of reference:

Such as Fig. 1 (a)-Fig. 1 (c), with the acquiescence Cartesian coordinate initial point of Pro/E software for modeling initial point O, creating radius is The Surface of Sphere of 13.4mm, the equation of Surface of Sphere is x²+y²+z²=13.4².Cross (0,0 ,-13.4) and make (x-13)²+y²=[13+ (z+ 13.4)tanα)]²Taper seat, wherein α=3 °.According to the modeling procedure of leaflet, obtain designing with Surface of Sphere for reference plane The monolithic leaflet model of biovalve, monolithic leaflet is carried out circumferential array using the rotary shaft of taper seat as central shaft, so After obtain three entity biology leaflets.

2, the face of cylinder is as the parameter model of the plane of reference:

Such as Fig. 2 (a)-Fig. 2 (c), with the acquiescence Cartesian coordinate initial point of Pro/E software for modeling initial point O, creating equation is ${(x\cos \frac{\mathrm{\π}}{4}-z\sin \frac{\mathrm{\π}}{4})}^2+y^2={13}^2$ The face of cylinder, mistakeMake Taper seat, wherein α=3 °.According to the modeling procedure of leaflet, the biovalve obtaining designing with the face of cylinder for reference plane Monolithic leaflet model, carries out circumferential array using the rotary shaft of taper seat as central shaft by monolithic leaflet, then obtains three realities Body biology leaflet.

3, the paraboloid of revolution is as the parameter model of the plane of reference:

Such as Fig. 3 (a)-Fig. 3 (c), with the acquiescence Cartesian coordinate initial point of Pro/E software for modeling initial point O, according to parameter side Journey x=13 × t, y=0, z=(13 × t)²/ 13 create x²The parabola of=13z, with Z axis as rotary shaft, establishment equation is x²+ y²The paraboloid of revolution of=13z.Cross (0,0,0) and make (x-13)²+y²=(13+ztg α)²Taper seat, wherein α=3 °.According to lobe The modeling procedure of leaf, obtains the monolithic leaflet model of the biovalve designed with the paraboloid of revolution for reference plane, by monolithic lobe Leaf carries out circumferential array using the rotary shaft of taper seat as central shaft, then obtains three entity biology leaflets.

4, ellipsoid is as the parameter model of the plane of reference:

Such as Fig. 4, with the acquiescence Cartesian coordinate initial point of Pro/E software for modeling initial point O, creating equation is Ellipsoid, wherein a=13.4, b=14.8.Crossing (0,0 ,-14.8) as equation is Taper seat, central shaft is x=13, α=3 °.In this model, ellipsoid equation isTaper seat Equation is (x-13)²+y²=[13+ (z+14.8) tg α]².According to the modeling procedure of leaflet, obtain with ellipsoid as reference plane The monolithic leaflet model of the biovalve of design, carries out circumference battle array using the rotary shaft of taper seat as central shaft by monolithic leaflet Row, then obtain three entity biology leaflets.

Systematic parameter by Pro/E software, it can be deduced that the precise geometrical parameter of the leaflet model designed, four kinds are not Physical dimension parameter with the biovalve model of profile is as shown in table 1.

The physical dimension parameter of the biovalve model of 1 four kinds of different profiles of table

(2) human aortic parameter such as Fig. 5 that this research provides according to Qianfo Mount hospital, enters tremulous pulse hole in PRO/E Row three-dimensional reconstruction, takes three leaflets and combines plane on the basis of the plane at place, midpoint, limit, set up successively according to image scanning parameter The datum plane that distance datum plane distance is 6mm, 12.24mm, 18mm and 24mm, with three lobes on corresponding datum plane The geometric center of leaf is 120 ° of circular arcs that initial point draws corresponding a diameter of 35.52mm, 38.64mm, 30.24mm successively, obtains Grass carries out curve fitting after plotting, and obtains threedimensional model such as Fig. 5 institute of lobe hole after application boundary mixing order geometric array Show.

(3) the indirect fluid-solid coupling model modeling of bioprosthetic valve

The indirect fluid-solid coupling model of bioprosthetic valve includes leaflet and the solid domain of arterial wall, the fluid domain of blood and lobe Leaf and the coupling surface of blood.Under the physiological environment of human body cardiac valve distributed about blood, under the impact of blood realize The keying of valve.In conjunction with actual, it is considered that the active lobe hole of arterial wall and blood vessel are full of blood in this time sunykatuib analysis.If Entrance and the outlet of arterial wall are closed and carried out hypostazation, it is believed that whole arterial wall model is fluid model.The present invention In use with PRO/E carries out solid modelling.Import to, in ANSYS, go forward side by side by the modeling in PRO/E with the form of IGES Row stress and strain model, obtains indirect fluid-solid coupling model.

Fig. 6 is physical model and the FEM (finite element) model of the valve after importing ANSYS.

2, material properties

The most conventional biovalve material is mainly aortic valve and the bovine pericardial material of pig, and their main material is Cardiac muscle fiber, cardiac muscle fiber is a kind of nonlinear cohesive material.Material should be taken into full account when biovalve is simulated This kind of characteristic.This analysis is determined according to the data of the stress strain curve of the fresh bio valvular tissue material measured Justice material, stress strain curve is as shown in Figure 7.

3, boundary condition is applied

In conjunction with the practical situation of biovalve work, we define the coupling surface of blood and leaflet is three biovalve lobes The upper and lower surface of leaf and the cross section of leaflet free margins through-thickness, it is known that it is fluid structurecoupling face that three leaflets have 9 faces. The import and export in convection cell territory are configured, and in blood entry port boundary condition sets, set the speed of fluid according to clinical data For 1m/s, in blood export boundary condition sets, pressure is set to 0, as shown in Figure 8.

Owing to biovalve leaflet is made up of porcine aortic valve or bovine pericardium, biovalve leaflet material belongs to super-elasticity material Material.The data that cardiac valve room according to Shandong ProvinceQianfoshan Hospital provides, leaflet material is the material of homogenizing uniform thickness, and thickness is 0.45mm.

Biovalve lobe frame material employing titanium alloy, its hardness leaflet to be far above material, thus assume that the characteristic of lobe frame For perfect rigidity, ignore the deformation of lobe frame.Now leaflet edge AC is securely attached on lobe frame, on AC limit the displacement of each point to Amount is zero, and AC limit is applied staff cultivation.AB Yu BC is free margins, as shown in Figure 9.

4. biovalve wind-structure interaction

(1) dynamic analysis of blood

In experimental analysis, it is considered to Tricuspid valve answers mechanical change under the action period under blood impacts.In fluid analysis, Setting blood entry port speed as 1m/s, outlet is set as that pressure is zero, and the density of blood is set as 0.98g/cm³。

By the setting of fluid modules in ANSYS, fluid blood inside arterial wall, will be closed as, definition material attribute, draw Subnetting lattice, apply boundary condition and post processing after can obtain the kinestate of single blood particles, in order to we observe Simplicity, we choose single particle ten kinds of moment in whole motor process and obtain the blood velocity profile such as figure of sampled point 10.Then we obtain blood pressure curve chart such as Figure 11 of sampled point according to same way.

By the speed curve diagram of blood it is clear that, when the time is 0.4s, the speed of blood is maximum, now selects The blood pressure of the single particle taken, also in maximum, then causes weakening and pressing of speed due to after the touching of blood and leaflet The increase of power, after blood is completely by leaflet, the speed of blood begins to ramp up, because the outlet of arterial wall is set to pressure It is zero, it is possible to be clearly seen blood on a declining curve after by leaflet, until reducing to zero in outlet pressure.

(2) dynamic analysis of leaflet

Valve time dependent Stress Map such as Figure 12, uniform in the stress distribution analyzing initial stage leaflet, the knot of leaflet The central area, combination limit closing limit and sew up region and the leaflet intersected on border all there occurs stress concentration phenomenon.The stitching of leaflet While relatively big relative to the abdominal part stress of leaflet, the stress concentration phenomenon at this may be such that leaflet is damaged, and causes leaflet Service life shortens.To consider the region easily occurring stress to concentrate when designing valve, reduce or prevent stress and concentrate existing As thus avoid leaflet to damage, improve leaflet durability.

B. different leaflet profiles are to biovalve dynamic mechanical impact analysis

Preferable bioprosthesis valve moulding should meet the properties requirement of natural heart lobe, but these requirements are the most mutually Restriction, it is impossible to meet optimum simultaneously.Using ball profile, ellipsoid profile, rotary parabolic profile and cylinder profile as leaflet It is analyzed contrast with reference to profile.

(1) different leaflet profile equivalent stress are analyzed

Finite element analysis software is utilized to be simulated analyzing, ball profile, ellipsoid profile, rotary parabolic under blood impacts Shown in equivalent stress such as Figure 13 (a)-Figure 13 (d) of Stress Map over time of profile and cylinder profile leaflet.

Stress distribution cloud atlas from the graph understands, and when 0.022s, four kinds of profiles all occur in that relatively high-stress area, ball-shaped Face, ellipsoid are distributed in, with the relatively high-stress area territory of paraboloid of revolution leaflet, the intersection combining limit with joining edge.The face of cylinder exists Leaflet combines the central area on limit and combines the intersection on limit and joining edge.When 0.044s, ball profile and the paraboloid of revolution The relatively high-stress area territory of leaflet adds again leaflet and combines the central area on limit, and relatively high-stress area territory, the face of cylinder combines limit in leaflet On occur in that again region at two.When 0.066s, the relatively high-stress area territory of paraboloid of revolution leaflet combines in leaflet and increases again on limit Add at two.Increasing over time, these regions are gradually increased.The stress of the face of cylinder and the paraboloid of revolution concentrates main distribution Combine the central area on limit in leaflet and combine the intersection on limit and joining edge.Ellipsoid and Surface of Sphere are mainly distributed on leaflet Intersection in conjunction with limit Yu joining edge.

The stress concentration distribution situation of the STRESS VARIATION cloud atlas drafting leaflet according to above-mentioned four kinds of profile leaflets:

The stress concentration distribution situation of the different profile leaflet of table 2

Comparatively speaking the region of stress concentration on the face of cylinder is relatively big, and the paraboloid of revolution takes second place, and stress concentration can cause leaflet Fatigue, so that leaflet calcification, causes valve failure.Can be seen that the stress distribution of four kinds of lobe types is the most uneven, stress is maximum Region be all the intersection on combination limit in leaflet and joining edge, the most easily there is the tear of valve, cause leaflet to lose efficacy. In terms of this angle, ellipsoid is much better with the leaflet dynamic mechanical of Surface of Sphere.

But from leaflet subjected to stress, Surface of Sphere stress is maximum, takes second place in the face of cylinder, and ellipsoid stress is minimum.

(2) different leaflet profile maximum principal stresses are analyzed

Finite element analysis software is utilized to be simulated analyzing, ball profile, ellipsoid, rotary parabolic under the impact of blood Shown in the Stress Map that the leaflet of profile and cylinder profile changes over time such as Figure 14 (a)-Figure 14 (d).

Above-mentioned simulation is analyzed for the various configuration of leaflet, according to the STRESS VARIATION cloud atlas of above-mentioned four kinds of profile leaflets The maximum principal stress such as table 3 of drafting leaflet:

The maximum principal stress of the different profile leaflet of table 3

From the graph it can be seen that ellipsoid is more apparent with the maximum principal stress skewness phenomenon of face of cylinder leaflet, rotation Turn parabola to take second place, the maximum principal stress distribution uniform of Surface of Sphere.Maximum principal stress skewness can cause along leaflet Deformation uneven, cause leaflet to be easily damaged.Smaller with ellipsoid of the maximum principal stress maximum of four kinds of profiles, rotation Turn parabola to take second place, be then Surface of Sphere.Relative to other profiles, the maximum principal stress on the face of cylinder is in its value and stress distribution Mechanical property is the most poor.

(3) the maximum shear stress analysis of different leaflet profiles

Utilizing finite element analysis software to be simulated analyzing, under the impact of blood, ball profile, ellipsoid profile, rotation are thrown The cloud atlas that the leaflet of thing profile and cylinder profile changes over time such as Figure 15 (a)-Figure 15 (d).

Knowable to stress distribution cloud atlas, the stress distribution of four kinds of lobe types is the most uneven, and the region of stress maximum is all in leaflet The intersection of combination limit and joining edge.The region of stress concentration of Surface of Sphere leaflet is distributed in the boundary combining limit with joining edge Place, the region of stress concentration of the face of cylinder and paraboloid of revolution leaflet is combined the central area on limit in leaflet and combines limit and joining edge Intersection.Comparatively speaking the region of stress concentration on the face of cylinder is relatively big, and the paraboloid of revolution takes second place, and the stress distribution of Surface of Sphere is relative Uniformly.But from leaflet subjected to stress, Surface of Sphere stress is maximum, takes second place in the face of cylinder, and ellipsoid stress is minimum.

The com-parison and analysis of (4) four kinds of leaflet profile mechanical properties

By the equivalent stress of four kinds of profile leaflets, shear stress and distribution of principal stress cloud atlas it can be seen that four kinds of types Face leaflet all occurs in that stress distribution non-uniform phenomenon in various degree, and region of stress concentration is slightly different.In effects such as analyses During power, ellipsoid and Surface of Sphere stress concentration phenomenon are mainly distributed on the combination limit of leaflet and the intersection of joining edge, and cylinder Face and the paraboloid of revolution are also distributed in leaflet and combine the central area on limit, and wherein the stress concentration phenomenon on the face of cylinder is the most serious. Equivalent stress maximum region is all the intersection on the combination limit in leaflet and joining edge.But analyze from leaflet subjected to stress value, Surface of Sphere stress is maximum, takes second place in the face of cylinder, and ellipsoid stress is minimum.When analyzing principal stress, stress maximum is both present in certainly Relatively big by the central area on limit, the face of cylinder and ellipsoid stress distribution inequality region, Surface of Sphere is the most uniform.But it is subject to from leaflet Stress value analysis, face of cylinder stress is maximum, and Surface of Sphere takes second place, and ellipsoid stress is minimum.When analyzing shear stress, ellipsoid Concentrate with Surface of Sphere stress and be mainly distributed on the combination limit of leaflet and the intersection of joining edge, and the face of cylinder and the paraboloid of revolution divide Cloth region is relatively big, and wherein the stress concentration phenomenon on the face of cylinder is the most serious.But analyzing from leaflet subjected to stress value, Surface of Sphere is subject to Power is maximum, takes second place in the face of cylinder, and ellipsoid stress is minimum.Knowable to above-mentioned analysis, face of cylinder mechanical property in every respect is the most relatively Difference, and the paraboloid of revolution, Surface of Sphere and ellipsoid have respective advantage at different aspect, in the design optimization after leaflet It is analyzed mainly for the paraboloid of revolution, Surface of Sphere and ellipsoid.

Although the detailed description of the invention of the present invention is described by the above-mentioned accompanying drawing that combines, but not the present invention is protected model The restriction enclosed, one of ordinary skill in the art should be understood that on the basis of technical scheme, and those skilled in the art are not Need to pay various amendments or deformation that creative work can make still within protection scope of the present invention.

Claims (3)

1. the analysis method optimized based on ANSYS/Workbench artificial heart valve film dynamic performance, is characterized in that: include Following steps:

(1) intercouple with solid domain based on fluid domain, build fluid governing equation, solid governing equation, determine fluid structurecoupling Interface, calculates and acts on the power in valve leaflets；

(2) based on ANSYS/Workbench, the interaction between blood and three leaflets is carried out fluid structurecoupling dynamic mechanical Performance evaluation；

(3) with Surface of Sphere, the face of cylinder, the paraboloid of revolution and four kinds of surface of revolutions of ellipsoid for the biovalve prototype plane of reference, point The mechanical property of the different biovalve configuration of analysis, and contrast；

In described step (1), because solid domain and fluid domain the most do not exist lap, therefore can only be at leaflet and blood Interface on there is fluid structure interaction because the ability that valve itself does not actively shrink, the opening and closing of leaflet is depended on completely In the flexible traction force to leaflet of blood and annulus, the theory that fluid domain and solid domain intercouple illustrates and flows on coupling surface The power of body node acts on solid node, thus promotes the motion of solid；

In described step (1), the method building fluid governing equation is:

Blood is incompressible liquid, therefore the fluid domain of blood uses incompressible Navier Stokes fluid controlling party Journey describes:

In above formulaFor the velocity vector of any point in blood；ρ is density of blood；μ is the viscosity of blood；P is the pressure of blood；F For acting on the body force of blood, human body is supplied to blood；T is the time；Gradient operator for current configuration；

In order to simplify calculating, above formula is carried out nondimensionalization:

In above formula, Re is Reynolds number, Re=ρ_fUL/ η, U are the flow velocity of fluid；ρ_fFor fluid density；η is viscosity coefficient, and L is characterized Length, f is the body force that human body acts on blood；

In described step (1), build solid governing equation method particularly includes:

What solid governing equation described is the deformation of solid under hydrokinetic effect, for the problem of blood Yu valve, definition Solid i.e. valve is nonlinear elastic material, the stress equation of valve:

ρ in above formula_sDensity for solid；ρ_fFor density of blood；Acceleration for solid；σ _sStress tensor for structure；For Act on the body force of solid；

In described step (1), determine that the method at fluid structurecoupling interface is:

Fluid is coupling surface Γ with the interaction part of solid_sf, coupling surface has speed seriality and surface force seriality, because of This, the position of coupling surface:

In above formulaFor horizontal domain set domain,For the displacement of leaflet,

The speed of coupling surface and acceleration:

In above formulaFor the speed of blood on coupling surface；For the displacement of leaflet on coupling surface,

In above formulaFor the acceleration of blood on coupling surface,Acceleration for leaflet；

In above formula,σFor stress tensor；For the local approach vector of coupling surface, subscript s and f represent solid and fluid respectively.

Analyze method the most as claimed in claim 1, it is characterized in that: in described step (2), concrete grammar includes:

A. use PRO/E that biovalve leaflet and arterial wall are carried out d solid modeling；

B. ANSYS/Workbench program is used, according to the stress-strain relation of the fresh bio valvular tissue material measured The data of curve define valvular material；

C. biovalve leaflet is imported Workbench program with arterial wall model with the form of IGES and carries out stress and strain model, Obtain fluid structurecoupling dynamic mechanical analysis FEM (finite element) model；

D. the parameter provided according to medical research applies fluid structurecoupling boundary condition；

E. by indirect fluid-solid coupling analytical calculation, the stress distribution situation of Cardiac valve prosthesis leaflet and blood are drawn Motion conditions.

Analyze method the most as claimed in claim 2, it is characterized in that: described step (3) method particularly includes:

A. four kinds of leaflet profiles are analyzed all in accordance with the step of A, B, C, D in step (2)；

B. by indirect fluid-solid coupling analytical calculation, draw the maximum principal stress of Cardiac valve prosthesis leaflet, equivalent stress with And the distribution situation of the maximum shear stress, and four kinds of valve configuration mechanical properties are analyzed contrast.