Simulation of corrosion and mechanical degradation of additively manufactured Mg scaffolds in simulated body fluid

TL;DR

This paper presents a finite element simulation strategy to predict corrosion and mechanical degradation of biodegradable Mg scaffolds in simulated body fluid, aiding in the design of biomedical implants.

Contribution

Developed a novel finite element simulation approach combining corrosion and mechanical models for Mg scaffolds in body fluid environments.

Findings

Simulation predictions matched experimental strength and fracture data.

Corrosion significantly affects mechanical integrity of Mg scaffolds.

The model can assess degradation effects for scaffold design.

Abstract

A simulation strategy based in the finite element model was developed to model the corrosion and mechanical properties of biodegradable Mg scaffolds manufactured by laser power bed fusion after immersion in simulated body fluid. Corrosion was simulated through a phenomenological, diffusion-based model which can take into account pitting. The elements in which the concentration of Mg was below a certain threshold (representative of the formation of Mg(OH)2) after the corrosion simulation were deleted for the mechanical simulations, in which Mg was assumed to behave as an isotropic, elastic-perfectly plastic solid and fracture was introduced through a ductile failure model. The parameters of the models were obtained from previous experimental results and the numerical predictions of the strength and fracture mechanisms of WE43 Mg alloy porous scaffolds in the as-printed condition and after immersion in simulated body fluid were in good agreement with the experimental results. Thus, the simulation strategy is able to assess the effect of corrosion on the mechanical behavior of biodegradable scaffolds, which is critical for design of biodegradable scaffolds for biomedical applications.