Research Laboratory for the Mechanics of Bio-compatible Materials and Devices

Scientific results:

• An extended two-level statistical model of inelastic deformation is proposed to describe the mechanical behavior of multicrystalline material of 316L alloy coronary stent was developed.
• A 2D vertex mathematical model of cell growth in the pores of a perfusion bioreactor
• Methods for modeling individual stages of the degradation process (surface or volumetric) were proposed, which act as an auxiliary tool, complementing existing dynamic models of structure degradation and allowing to expand the understanding of the individual contribution of surface and volumetric degradation to the mechanical behavior of the structure.
• A model of multiple crack development in structural elements of the scaffold was developed based on algorithms for determining stress concentration zones and cluster analysis approaches. The analysis demonstrated significant differences in mechanical properties and performance characteristics of scaffolds with different design but the same level of porosity.
• The most promising approaches for describing the bone adaptation process are explored, which incorporate different aspects of the underlying real process allowing the best approach to be selected for modeling specific loading scenarios.
• A microstructure design system is developed using genetic algorithm and property distribution analysis. Optimal hyperparameters are found for microstructure generation that deliver the required mechanical response based on the stresses in the finite elements and their volume.
• Periodic structures based on TPMS were developed taking into account the morphometric characteristics of the reference model of bone tissue. A number of models that optimally simulate bone in terms of mechanical and averaged morphometric characteristics have been defined.
• The effect of functional gradient on morphometric and mechanical properties of bone scaffolds was investigated. Scaffold models designed for bone replacement in the transitional trabecular-cortical area were developed. An approach for designing structures with a morphology gradient is proposed.
• A theoretical study of the permeability of porous chips incorporated into a perfusion bioreactor for tissue culture has been carried out. Several kinds of porous materials with a gradient of porosity in the flow direction based on thrice periodic minimal surfaces were built.
• A mathematical model of FFF/FDM 3D printing process with application of operational control in the algorithm of numerical realization was developed. The model was verified by means of full-scale experiment on surfacing of polylactide samples and thermography data.
• According to the results of complex experimental study of additively manufactured polylactide samples, the influence of strain rate on the values of tensile strength and modulus of elasticity was established.
• Mechanical characteristics of thermoplastic materials used for three-dimensional printing of structural elements of exoprostheses were verified on the basis of the results of strain measurements by fiber-optic sensors.
• Using tomography results, defects occurring during additive manufacturing and the effects of physiological environments that can influence the mechanical performance of such structures were identified.
• Multistage degradation processes of biocompatible polymeric materials in saline and distilled water at different temperatures were studied.
• The morphological features and stiffness characteristics of the polylactide surface depending on the ion dose of plasma treatment were evaluated. It was found that the ion flux angle significantly affects the atomization of polylactide, which can affect the physical and mechanical characteristics and morphology of the material surface.
• A methodological approach to assess the biocompatibility of samples with in situ staining of adhered cells with lipophilic fluorochrome PKH26, which allows quantitative assessment of cell adhesion to polymeric materials, was developed.
• A methodology of structural and topological design of hip endoprostheses with porous structure was developed.
• Data on the ductile nature of fracture of three-dimensional models of cellular scaffolds made of Ti6Al4V powder with local elements characteristic of brittle fracture was obtained.
• A methodology for the design of three-dimensional microstructures of porous materials with optimal properties based on the StyleGAN2 neural network was developed.

Organizational and infrastructural changes:

A new research laboratory has been established, equipped with research equipment worth a total of more than 75 million of rubles, including:

1. A system for mechanical testing and analysis of the stress-strain state of biocompatible materials.
2. A robotic cell for multi-axis 3D printing and laying of thermoplastic composite material.
3. A Coxem EM-30 Plus scanning electron microscope.
4. A Dr. INVIVO 4D2 bioprinter.

Education and personnel occupational retraining:

During the course of the project, the laboratory staff defended 3 doctoral dissertations and 3 candidate dissertations. Additionally, 4 bachelor's theses and 4 master's theses on the project topic were defended. Fourteen laboratory staff members underwent advanced training in leading Russian scientific organizations.

A new educational program for the master's profile "Dynamics and Strength of Machines, Structures, and Mechanisms” has been developed and implemented.

A new educational program for the postgraduate profile "Mechanics of Biomaterials" has been developed and launched.

Cooperation:

1. Immanuel Kant Baltic Federal University
2. N.G. Chernyshevsky Saratov National Research State University
3. M.K. Ammosov North-Eastern Federal University
4. Academician E.A. Wagner Perm State Medical University
5. Perm Federal Research Center of the Ural Branch of the Russian Academy of Sciences
6. Polytechnic College of the Applied Research Institute of Abu Dhabi (UAE)
7. Sultan Qaboos University (Oman)