X-ray physics-based CT-to-composition conversion applied to a tissue engineering scaffold, enabling multiscale simulation of its elastic behavior

Karol Szlązak , Viktoria Vass , Patricia Hasslinger , Jakub Jaroszewicz , A. Dejaco , Joanna Idaszek , Stefan Scheiner , C. Hellmich , Wojciech Święszkowski

Abstract

Nowadays, the assessment of the mechanical competence of tissue engineering scaffolds based on computer simulations is a well-accepted technology. Typically, such simulations are performed by means of the Finite Element (FE) method, with the underlying structural model being created based on micro-computed tomography (microCT). Here, this analysis modality is applied to a new, ternary composite, consisting of PHBV, i.e. poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PLGA, i.e. poly(lactic-co-glycolide), as well as of TCP, i.e. tricalcium phosphate hydrate. The studied scaffold structure is made up by fibers of this new composite material, manufactured by means of the rapid prototyping method. The data collected from microCT is utilized for adequately defining the mechanical properties of the FE model. In particular, the three-dimensional field of grey values is interpreted in terms of the underlying field of attenuation coefficients, taking into account the photon energy employed in microCT imaging, eventually allowing for calculation of the three-dimensionally distributed, voxel-specific composition of the studied material. For the sake of keeping the FE simulations as efficient as possible, groups of voxels are combined into one finite element; the grey value of the latter is obtained by volume averaging. Employing a two-step micromechanical homogenization scheme, the experimentally accessible stiffness of the three constituents (PHBV, PLGA, and TCP) is then, finite element by finite element, upscaled to the composition-dependent stiffness of the composite material. The plausibility and adequacy of the FE model is demonstrated by simulating the effects of uniaxial compression on the scaffold structure, in terms of resulting stress and strain fields, highlighting the importance of the fiber junctions (as they are the mechanically most stressed regions), and that neglecting the material heterogeneity would lead to a potentially significant underestimation of stresses and strains. Finally, a comparison is made of the employed analysis modality of microCT data with a previously pursued, simplified analysis strategy, highlighting the conceptual superiority of the former, and pointing out the application limits of the latter.
Author Karol Szlązak (FMSE / DMD)
Karol Szlązak,,
- Division of Materials Design
, Viktoria Vass - [Technische Universitat Wien]
Viktoria Vass,,
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, Patricia Hasslinger - [Technische Universitat Wien]
Patricia Hasslinger,,
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, Jakub Jaroszewicz (FMSE / DMD)
Jakub Jaroszewicz,,
- Division of Materials Design
, A. Dejaco - [Technische Universitat Wien]
A. Dejaco,,
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, Joanna Idaszek (FMSE / DMD)
Joanna Idaszek,,
- Division of Materials Design
, Stefan Scheiner - [Technische Universitat Wien]
Stefan Scheiner,,
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, C. Hellmich - [Technische Universitat Wien]
C. Hellmich,,
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, Wojciech Święszkowski (FMSE / DMD)
Wojciech Święszkowski,,
- Division of Materials Design
Journal seriesMaterials Science & Engineering C - Materials for Biological Applications, ISSN 0928-4931, (A 30 pkt)
Issue year2019
Vol95
Pages389-396
Publication size in sheets0.5
Keywords in EnglishPHBV, PLGA, TCP, Micromechanics, Numerical simulation, Attenuation coefficient, Photon energy, Micro-computed tomography
ASJC Classification2210 Mechanical Engineering; 2211 Mechanics of Materials; 3104 Condensed Matter Physics; 2500 General Materials Science
DOIDOI:10.1016/j.msec.2017.11.044
URL https://www.sciencedirect.com/science/article/pii/S0928493117302540
Languageen angielski
File
1-s2.0-S0928493117302540-main.pdf 1.57 MB
Score (nominal)30
ScoreMinisterial score = 30.0, 25-04-2019, ArticleFromJournal
Ministerial score (2013-2016) = 30.0, 11-03-2019, ArticleFromJournal
Publication indicators Scopus Citations = 1; WoS Citations = 1; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 1.384; WoS Impact Factor: 2017 = 5.08 (2) - 2017=4.628 (5)
Citation count*2 (2019-08-22)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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