Study On Soft Tissue Biaxial Tensile Test Bench And Constitutive Model

Virtual surgical systems have developed rapidly in recent years.How to accurately simulate the real changes of organs and soft tissues in virtual surgical systems has become a key issue to be solved in the development of new technologies.In order to better simulate the soft tissue deformation in real surgery,a soft tissue biaxial stretching test bench was developed and used to conduct equiaxed tensile experiments on soft tissues to obtain soft tissue biaxial mechanical properties.The soft tissue biaxial force data is processed by parameter inversion method to obtain the constitutive model parameters,and finally the physical model which can describe the soft tissue deformation is obtained.The soft tissue biaxial tensile test specimens and clamping methods were studied for the nonlinearity,anisotropy,hysteresis and heterogeneity of soft tissues.Analyze the load transfer mechanism of common bio-machine connection method,carry out finite element simulation on the shape of soft tissue sample and study the action mechanism of soft tissue sample shape on stress change in soft tissue central region,and finally obtain the bio-machine contact mode suitable for soft tissue.And the shape of the square sample.After determining the shape of the square specimen and the contact mode of the biomachine,the soft tissue biaxial stretching test bench was designed and built.Write the motor control part program and design the front panel of the control program to achieve equiaxed stretching of the soft tissue.After visual preprocessing and feature recognition in the Open CV environment,a displacement acquisition system based on CCD camera is designed by imaging principle and optimized to meet the experimental requirements.The equiaxed tensile test of the gastric wall muscle tissue was performed using a soft tissue biaxial test bench,and the force position data of the soft tissue biaxial stretching was recorded.Aiming at the problem of using the experimental force data to obtain the optimal soft tissue model parameters,a parameter inversion method based on Matlab and Abaqus co-simulation is proposed.Based on the simulated annealing algorithm,the Abaqus program was called by Matlab to obtain the GOH physical model parameters characterizing the soft tissue mechanical properties.The validity of the proposed parameter inversion method was verified by finite element simulation and four parameters in the GOH model were obtained based on the experimental data.Finally,a constitutive model that better describes the soft tissue deformation is obtained.