Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Experimental characterization and computational modelling of the effect of in vitro corrosion on the mechanical integrity of biodegradable magnesium alloy WE43 for orthopedic applications
Submission Author:
Felipe Saconi , SP
Co-Authors:
Felipe Saconi, Anish Roy, Marcelo Leite Ribeiro
Presenter: Felipe Saconi
doi://10.26678/ABCM.COBEM2021.COB2021-0051
Abstract
Biodegradable magnesium alloys are considered a promising candidate to replace the conventional bioinert metals, such as titanium alloys, used in trauma and extremities implants. Nowadays, large-scale utilization of magnesium implants is still restricted by the high corrosion rates and its unknown effects on implant structural integrity. Computational modeling plays an important role in the development and design of orthopedic implants for osteosynthesis. In the case of biodegradable metals, a modelling approach is required to predict the effects of degradation on the implant's mechanical integrity and its capacity to provide the desired stabilization of fractured bones. In this study, the mechanical behavior of magnesium WE43 alloy is modelled using the von Mises elastoplasticity model with isotropic hardening, coupled with a continuum damage mechanics model, to accounts for the effects of corrosion-induced microscale defects on the material mechanical resistance. The phenomenological corrosion model is implemented in a finite element framework, through the development of a user material subroutine (VUMAT) for use with the Abaqus/Explicit. The corrosion damage is assumed to be nonuniform, also known as localized pitting corrosion, which represents the heterogeneous corrosion on the materials free surface when exposed to an aggressive environment, as well as stress corrosion, which describes the stress-mediated localization of the corrosion attack through a stress-dependent evolution law. Both pitting and stress corrosion damages are implemented employing a nonlocal integral formulation, in order to overcome the mesh-dependency. The nonlocal pitting corrosion model is calibrated based on experimental data collected from in-vitro degradation experiments and mechanical testing of magnesium WE43 alloy wire specimens. The calibrated corrosion model accurately captures both the mechanical reduction in specimen resistance, in the form of failure strength with mass loss, as well as the non-linear corrosion behavior of magnesium WE43, observed experimentally.
Keywords
WE43 biodegradable magnesium alloy, Numerical simulation, continuum damage mechanics, pitting corrosion modelling, Finite Element Analysis
