Study On Multistage Magnetic Coupling Transmission System Of Artificial Heart

The magnetic external drive mechanical auxiliary circulation equipment is a new way of artificial heart.The blood compatibility and blood temperature rise of magnetic external drive mechanical auxiliary circulation equipment are better than the traditional artificial hearts.It is It can better meet the physiological needs of patients.Today,the performance of permanent magnet materials is limited,when the permanent magnet rotor is driven far from the axial bleeding pump,the blood pump can not work properly.In order to solve this problem,this paper explores the influence of parameters in the multi-stage magnetic coupling transmission system on the torque of the axial bleeding pump.According to the results of simulation calculation and simulation experiment,we can get a prediction model of multistage magnetic coupling drive system within a certain parameter range.It can help to determine the geometrical parameters of multistage magnetic coupling drive system.The main research contents of this peper includes:a.Analysis of magnetic force interaction between permanent magnets based on equivalent magnetic charge method.By calculating the magnetic force and magnetic moment between permanent magnets in the ideal state,I determined the objective factors affecting the stability of magnetic coupling between permanent magnets.b.Based on the finite element method,I research the influence of the change of permanent magnet radius,length and distance on the torque of axial bleeding pump.Firstly,I analyse the influence of the radius,length and distance of permanent magnet on the torque of axial bleed pump by ANSYS.Then,the simulation experiment of cardiopulmonary bypass corresponding to the simulation analysis was carried out to verify the accuracy of the simulation results.c.Research on the relationship between the torque of the axial bleeding pump and the multi-parameters based on the multi-objective analysis.According to the results of the significance analysis of each factor,the relationship between the factors with significant influence and the rotation of the axial bleeding pump in the multi-stage magnetic coupling drive model was explored.Firstly,the ANSYS finite element analysis software is used to simulate every factor under different variables according to the factorial test method,and then the correlation analysis of the simulation results is carried out by SPSS software,I know the correlation coefficient between each factor and the torque of the axial bleeding pump.Then,based on the least square method and quasi-Newtonian function,I carried out function fitting work.Finally,through the error analysis of linear prediction model and nonlinear prediction model,the mathematical prediction model of multistage magnetic coupling transmission model with higher accuracy was determined.From this research,the following conclusions are drawn:a.According to the calculation of the magnetic force interaction between cylindrical permanent magnets,the formula shows that the main factors affecting the magnetic force transmission between cylindrical permanent magnets are the radius and length of permanent magnets and the distance between the surfaces of two permanent magnets.Thus,it can be inferred that the influencing factors of the axial bleeding pump torque in the multi-stage magnetic coupling drive system are the radius and length of the active permanent magnet rotor₁ and7)₁,the radius and length of the passive permanent magnet rotorα₂ and7)₂,distance between the active permanent magnet rotor and the passive permanent magnet rotorα₁,the distance between the passive permanent magnet rotorαand the axial bleeding pump₂.There are six variables in the multistage magnetic coupling drive system.b.According to the results of the simulation analysis and cardiopulmonary bypass simulation experiment,the factors that have significant influence on the torque of the axial bleeding pump in the multi-stage magnetic coupling drive system were determined according to the F-value test and P-value test in the analysis of variance.The results of simulation analysis and cardiopulmonary bypass simulation experiment were analyzed by data visualization.We can know that₁,₂ and7)₂ are positively correlated with the magnetic torque.And₁ is negatively correlated with the magnetic torque.c.The phase relation value of the active rotor radius₁ is 0.007,it is a very significant impact on the torque of the axial bleeding pump.The phase relation value of the radius of passive permanent magnet rotorα₂ is 0.016,it is a very significant impact on the torque of the axial bleeding pump.The phase relation value of distance between the active permanent magnet rotor and the passive permanent magnet rotorα₁ is-0.003,it is a significant impact on the torque of the axial bleeding pump.The phase relation value of the radius of passive permanent magnet rotorα7)₂ is 0.006,it is a very significant impact on the torque of the axial bleeding pump.The error analysis results show that the four significant factors have a nonlinear relationship with the axial bleeding pump within the range of variables studied.The main work and contribution of this paper is to verify and obtain the factors₁,₂,₁ and7)₂ which have significant influence on the torque of axial bleeding pump in multistage magnetic coupling drive system.Through simulation calculation and experimental research,based on the least square method and quasi-Newtonian function,this paper carried out function fitting work.The prediction equation of the multi-stage magnetic coupling drive model is obtained by function fitting and error analysis of the simulation results.The prediction model can then be used to calculate the geometric dimensions of the active rotor and the passive rotorαin accordance with the body structure of different patients under the premise of meeting the working requirements of the axial bleeding pump,which is helpful to optimize and reduce the size of the mechanical auxiliary circulation of the multi-stage magnetic coupling drive,thus improving the convenience of the device.