Computational analysis of the effects of geometric irregularities and post-processing steps on the mechanical behavior of additively manufactured 316L stainless steel stents

  • Advances in additive manufacturing enable the production of tailored lattice structures and thus, in principle, coronary stents. This study investigates the effects of process-related irregularities, heat and surface treatment on the morphology, mechanical response, and expansion behavior of 316L stainless steel stents produced by laser powder bed fusion and provides a methodological approach for their numerical evaluation. A combined experimental and computational framework is used, based on both actual and computationally reconstructed laser powder bed fused stents. Process-related morphological deviations between the as-designed and actual laser powder bed fused stents were observed, resulting in a diameter increase by a factor of 2-2.6 for the stents without surface treatment and 1.3-2 for the electropolished stent compared to the as-designed stent. Thus, due to the increased geometrically induced stiffness, the laser powder bed fused stents in the as-built (7.11 ± 0.63 N) or the heat treated condition (5.87 ± 0.49 N) showed increased radial forces when compressed between two plates. After electropolishing, the heat treated stents exhibited radial forces (2.38 ± 0.23 N) comparable to conventional metallic stents. The laser powder bed fused stents were further affected by the size effect, resulting in a reduced yield strength by 41% in the as-built and by 59% in the heat treated condition compared to the bulk material obtained from tensile tests. The presented numerical approach was successful in predicting the macroscopic mechanical response of the stents under compression. During deformation, increased stiffness and local stress concentration were observed within the laser powder bed fused stents. Subsequent numerical expansion analysis of the derived stent models within a previously verified numerical model of stent expansion showed that electropolished and heat treated laser powder bed fused stents can exhibit comparable expansion behavior to conventional stents. The findings from this work motivate future experimental/numerical studies to quantify threshold values of critical geometric irregularities, which could be used to establish design guidelines for laser powder bed fused stents/lattice structures.

Export metadata

Additional Services

Share in Twitter Search Google Scholar Statistics
Author:Lisa WiesentORCiD, Ulrich Schultheiß, Philipp Lulla, Ulf Noster, Thomas SchratzenstallerORCiD, Christof Schmid, Aida NonnORCiDGND, Ashley SpearORCiD
Parent Title (English):PLoS ONE
Document Type:Article
Year of first Publication:2020
Release Date:2021/11/12
Tag:Deformation; Heat treatment; Lasers; Material properties; Powders; Specimen preparation and treatment; Stiffness; Surface treatments
GND Keyword:Koronarendoprothese; Rapid prototyping; Numerische Methode
Article Number:e0244463
First Page:1
Last Page:30
Corresponding author: Lisa Wiesent
Institutes:Fakultät Maschinenbau
Regensburg Center of Biomedical Engineering - RCBE
Technologie-Campus Neustadt an der Donau
Technologie-Campus Parsberg-Lupburg
Fakultät Maschinenbau / Labor Medizinprodukte
Fakultät Maschinenbau / Computational Mechanics and Materials Lab (CMM)
Fakultät Maschinenbau / Labor Werkstoffrandschichtanalytik
OpenAccess Publikationsweg:Gold Open Access- Erstveröffentlichung in einem/als Open-Access-Medium
Corresponding author der OTH Regensburg
research focus:Lebenswissenschaften und Ethik
Licence (German):Creative Commons - CC BY - Namensnennung 4.0 International