Determining hyper-viscoelastic structural properties of UHMWPE material used in Prodisc-C prosthesis employing a finite element–optimization coupling method

Choosing an appropriate material that owns favorable mechanical properties for decreasing wear and increasing the lifespan of the prosthesis is of great importance. This study aimed to determine the Prodisc-C prosthesis structural properties using the finite element coupling method and optimization algorithm. Another goal was to discuss and evaluate the von Mises stress and mechanical properties of Prodisc-C prosthesis including hyper-viscoelastic and viscoelastic properties. For this purpose, a two-dimensional model was built and further was simulated and discussed using Abaqus software. The model’s mechanical properties were obtained via an annealing optimization algorithm. The algorithm aimed to create conformity between stress relaxation diagrams achieved from each step of simulation and experimental tests. The obtained results confirmed a high similarity in terms of conformity between the optimized behaviors achieved from finite element based on the Moony–Rivlin and Neo-Hooke models and stress relaxation test results. Afterward, the acquired characteristic parameters were then employed in a three-dimensional structural model of Prodisc-C prosthesis to evaluate von Mises stress distribution under a compressive load of 73.6 N. After considering the hyper-viscoelastic properties of Moony–Rivlin for the upper part of the prosthesis, which was composed of cobalt, the maximum stress in the prosthesis was determined to be 429.7 MPa. However, for the lower part, which was composed of titanium, the stress was calculated to be 35 MPa. Moreover, the stress of the prosthesis polymeric core was evaluated to be 936 MPa, indicating an improvement in comparison to Neo-Hooke and prosthesis elastic properties.