Mechanical characterization of a hyperelastic biopolymer using nano-indentation experiment and finite element method

In this study the hyperelastic behavior of Bis-GMA was determined by nano-indentation experiment and finite element (FE) simulation method. For this purpose, the nano - indentation experiment was performed on Bis- GMA specimen according to its common method. A three dimensional hyperelastic FE model was employed to simulate the nano-indentation procedure. The uniaxial compression test was also done on Bis-GMA samples to measure the required material parameters for the FE model.Results of the nano-indentation experiment indicated that stress relaxation occurs in the Bis-GMA specimen when the indenter is held at the maximum indentation depth. The stress relaxation modulus in term of holding time was calculated from the results of nano-indentation experiment. Comparing the load-displacement curve obtained from the FE simulation with corresponding values of the nano-indentation experiment revealed good agreement when using a second order polynomial model.