Coupled Thermo-Mechanical Finite Element Analysis of Cranial Implants Using Micromechanical Representative Volume Element Approach

Fully coupled thermo-mechanical elasto-viscoplastic analysis of a typical cranial implant is presented by numerically analyzing the representative volume element (RVE) of an Implant. Surgical cranial implants constrained to patient skull during a cranioplasty procedure require elegant design due to immediate vicinity to sensitive brain tissue. A user subroutine UMAT is implemented in ABAQUS environment to implement the coupled thermo-mechanical elasto-viscoplastic constitutive behavior. A composite polyether ether ketone (PEEK) cranial implant with titanium alloy Ti6Al4V inclusions is analyzed by using the RVE technique. In biocompatible PEEK polymer with different inclusion geometry, porosity is analyzed. Unidirectional composite with hexagonal, square and random circular fibers is also analyzed. Random inclusions and porosity in a RVE are implemented through Python Scripts. Stress–strain behavior and residual stresses are evaluated at small temperature gradients as is case in implant tissue interaction. User implemented constitutive behavior is compared to the ABAQUS inbuilt constitutive model and good agreement is found.