Thom Bitter, A subject specific material model for human knee ligaments, 2012
(MSc. Project in collaboration with ORL-UMC St. Radboud)
For simulating knee behavior using a finite element analysis, accurate material descriptions are necessary. Biological soft tissues are known to behave in an anisotropic, nearly incompressible way and are subjected to large deformations. In this work a subject specific material model for human knee ligaments is created. Based on literature a transverse isotropic hyperelastic material model is selected; A fully elastic material reinforced with fibers in only one direction. The model has been made subject specific based on the following properties:
- An already available three-dimensional geometry
- Material coefficients determined from uniaxial material tests
- Local fiber directions based on centerlines
The material model is implemented in the finite element program Abaqus FEA using subroutines. This was successfully done for the explicit finite element method. For the implicit finite element method however, convergence problems result in an unusable implicit subroutine.