Modeling And Simulation Of Hyperelastic Materials In Cardiac Motion Process

Cardiac expansion-contraction is the basis for the function of the heart's blood transfusion,and the material properties of the heart play a decisive role in the size of the expansion-contraction.Because there is no uniform qualitative description of the characteristics of living heart materials,it is difficult to achieve the activity experiment by using traditional materials,it is difficult to carry out experiments using traditional materials to maintain the activity,and it is difficult and costly to conduct experiments on living hearts.Therefore,it is particularly important to establish a material model constitutive suitable for the large deformation of heart movement.Firstly,in view of the material characteristics of the heart,the control variable method is used to decoupled the existing mathematical model of myocardial tissue strain energy,and respectively deduced the analytical relations of isovolumetric strain energy,fiber tensile strain energy,shear strain energy and viscous strain energy.The theoretical model of cardiac strain energy equivalence was constructed according to the functional relationship between strain energies,and the theoretical model was verified by simulation fitting test.As a result,the equivalent relationship was within a reasonable error range,laying a foundation for accurately describing the mechanical characterization of cardiac incompressibility,hyperelasticity and viscoelasticity.Secondly,effective 3D spatial coordinates of the initial cardiac contour were extracted from the cardiac spatial point cloud database.DES editing technology was used to analyze and calculate the cardiac coordinate information,and the thickness distribution of each cardiac chamber was configured.Then,the shape of the heart was refined reasonably by using the surface modeling technology,and the finite element model of the heart was preliminarily completed.In addition,in order to obtain the parameters of cardiac mechanical material model,finite element simulation tests were conducted on three common mathematical models of hyperelastic materials(Mooney-Rivlin model,Ogden model and Yeoh model),and curve fitting and comparative analysis were conducted on the simulation results.The results showed that the fitting degree of Yeoh model(N=4)was 0.9963,which was consistent with the preliminary theoretical model of the heart.The material parameters were given to the initial finite element model for the machine-electrical coupling simulation test.At the same time,for the real object,the ecg data were obtained by using CT technology,and the experimental data and simulation data were compared.The results showed that the maximum residual of the two was 3.7261,meeting the error requirements.In addition,in order to obtain the parameters of cardiac mechanical material model,finite element simulation tests were conducted on three common mathematical models of hyperelastic materials(Mooney-Rivlin model,Ogden model and Yeoh model),and curve fitting and comparative analysis were conducted on the simulation results.Finally,based on the cardiac hyperelastic model,the ventricular side wall of hypertrophic cardiomyopathy was simulated,and the analysis data showed that the average peak load of the ventricular side wall of hypertrophic cardiomyopathy was lower than 0.8mpa,which could predict hypertrophic cardiomyopathy to a certain extent and provide a quantitative reference standard for the incidence of heart disease.