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Modeling of the Mechanical Behavior of Rapid Prototyped Scaffolds Based on Their Pore Architecture and Introducing a Prototyping Method to Produce Ceramic Scaffolds

Amirkhani, Soodeh | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43934 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza; Baghaban Eslaminejad, Mohamad Reza
  7. Abstract:
  8. Mechanical behavior of tissue engineering scaffolds plays a key role in their biological performance; however the effect of microstructural features on mechanical behavior of such scaffolds is still under investigation. The objective of this study was to investigate the influence of pore architecture and relative density on mechanical behavior of rapid prototyped scaffolds. In this regard, scaffolds with different cubic, hexagonal and trigonal unit cells were designed. These unit cells were repeated in different arrangements in 3D space to produce different nodal connectivities. The internal dimension of pores varied from 500 to 600 μm. Plastic models of scaffolds then fabricated by 3D printing in cubes of 1cm in each dimension. An in situ imaging technique was utilized to study the progressive compressive deformation of the scaffold models. The effects of loadig direction and nodal connectivity on mechanical behavior were investigated using scaffolds with the same relative density. In both cubic and hexagonal geometries, organized buckling patterns relevant to each unit cell were observed at the onset of plastic deformation. These patterns were in good agreement with the elastic stress concentration patterns generated by finite element simulation. A wide range of compressive behaviors, from elastic-plastic to fully brittle, was observed in the studied scaffolds made of the same material. The Maxwell necessary criterion for rigidity was used to explain mechanical behavior of the scaffolds. It is well demonstrated in this study that pore architecture may highly affect mechanical properties of such structures. In other words, modulus of elasticity varied from 151 to 326 MPa and maximum strength from 4.8 to 13.6 MPa in a same relative density. An analytical model based on dimensional analysis is also proposed in this study to predict moulus of elasticity. Moreover, the effect of relative density (0.17-0.4) was investigated and it is shown that mechanism of deformation along side porosity should be considered as a criterion in designing rapid prototyped scaffolds. At last a reproducible method is introduced to fabricate ceramic scaffolds based on rapid prtototyping technique. In addition, failure mechanism and in vitro biocompatibility of ceramic scaffolds are reported
  9. Keywords:
  10. Tissue Engineering ; Rapid Prototyping ; Scaffold ; Mechanical Properties ; Relative Density

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