Computer simulation of damage analysis in a polyurethane sample with a carbonized layer on the surface using atomic force microscopy

• Main Authors: Garishin, Oleg K., Sokolov, Aleksandr K., Svistkov, Aleksandr L., Izumov, Roman I.
• Format: Conference Proceeding
• Language: English
• Subjects: Atomic force microscopy; Biocompatibility; Carbon; Computer simulation; Creep (materials); Damage assessment; Deformation effects; Microcracks; Microscopy; Nanoindentation; Polyurethane resins; Prostheses; Surface cracks; Tissues
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0135067

The article presents results of computer modeling of the AFM probe contact with polyurethane samples with carbonized nanocoating. Such materials are commonly used in medicine as endoprostheses. Reliable determination of the presence and distribution of microcracks in the carbon layer of the endoprosthesis surface is important from the point of view of assessing the biocompatibility and possible trauma of living tissues in the contact zone. The main task of this research was to find an answer to the question whether it is possible to determine the presence of microdamages in polyurethane hidden under the carbonized coating using atomic force microscopy and to classify them. It is obvious that such internal microcracks can aggravate significantly the damaging effect of surface cracks on living biological tissue during endoprosthesis deformation - an increase in the divergence of the crack edges, creeping of one edge to the other (scissor effect), etc. Three variants of local microdamages that may arise in such samples were considered. a) There is a vertical crack in the surface carbon nanolayer and no damages in polyurethane. b) An adhesion detachment between the layer and the polyurethane is added to the vertical crack in the nanolayer (horizontal crack). c) Cohesive damage of polyurethane (vertical crack) is added to the vertical crack in the nanolayer. It is shown that using atomic force microscopy it is possible to accurately determine the presence of microcracks in the surface carbon nanolayer, while the microdamages of polyurethane itself hidden under it have a much weaker effect on nanoindentation. That is, this approach does not allow one to reliably judge what damages are present in the inner surface regions of the material, although it makes it possible to assess their presence.