NON-LINEAR MASS-SPRING SYSTEM FOR LARGE SOFT TISSUE DEFORMATIONS MODELING
Operation of implant placement under soft tissues is described. In this operation, tissues can reach such deformations that nonlinear properties appear. A mass-spring model modification for nonlinear tension operation modeling is developed. A method for elasticity module creating using splines is described. Poisson ratio modeling is done by different stiffness for different types of springs in cubic grid. For stiffness value definition, a system of equations is solved describing material tension. The model is verified by experiment on square sample tension. Tests show that sample tension under external forces is equal to defined nonlinear elasticity module. The accuracy of Poisson ratio modeling is thirty five percent that is better than results of available ratio modeling method.