Manipulating failure mechanism of rapid prototyped scaffolds by changing nodal connectivity and geometry of the pores

Amirkhani, S ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.jbiomech.2012.08.029
  3. Publisher: 2012
  4. Abstract:
  5. The performance of cellular solids in biomedical applications relies strongly on a detailed understanding of the effects of pore topology on mechanical properties. This study aims at characterizing the failure mechanism of scaffolds based on nodal connectivity (number of struts that meet in joints) and geometry of the pores. Plastic models of scaffolds having the same relative density but different cubic and trigonal unit cells were designed and then fabricated via three dimensional (3-D) printing. Unit cells were repeated in different arrangements in 3-D space. An in-situ imaging technique was utilized to study the progressive deformation of the scaffold models. Different nodal connectivities resulted in a wide range of compressive behaviors in scaffold models, from elastic-plastic to fully brittle. The Maxwell necessary criterion for rigidity was used to explain mechanical behavior of the scaffolds. Nodal connectivity of 4 satisfied Maxwell's criterion for rigidity in the examined structures. In a stress-strain curve of scaffolds with cubic unit cells and nodal connectivities of 3 and 4, pore deformation was observed after yielding. On the other hand, scaffolds with trigonal unit cells and nodal connectivities of 4 and 6, exhibited brittle behavior in the absence of pore deformation. These results highlight the role of nodal connectivity on failure mechanism and subsequently mechanical performance of scaffolds. This study reveals that appropriate pore geometry can provide sufficient condition for rigidity when Maxwell's necessary condition is satisfied. In addition, this study demonstrates that Maxwell's criterion can be used in pre-designing of pore geometries for scaffolds with distinct nodal connectivities
  6. Keywords:
  7. Maxwell's criterion ; Rapid prototyped scaffolds ; 3-D space ; Biomedical applications ; Brittle behavior ; Cellular solids ; Compressive behavior ; Cubic unit cells ; Elastic-Plastic ; Failure mechanism ; Mechanical behavior ; Mechanical performance ; Plastic models ; Pore geometry ; Progressive deformation ; Sufficient conditions ; Unit cells ; Biomechanics ; Buckling ; Cells ; Cytology ; Deformation ; Elastoplasticity ; Geometry ; Imaging techniques ; Maxwell equations ; Medical applications ; Rigid structures ; Stress-strain curves ; Three dimensional ; Scaffolds (biology) ; Plastic ; Rapid prototyped scaffold ; Tissue scaffold ; Unclassified drug ; Controlled study ; Cubic unit cell ; Elasticity ; Foam ; Mathematical parameters ; Maxwell criterion ; Mechanics ; Nanopore ; Nodal connectivity ; Physical parameters ; Plasticity ; Priority journal ; Relative density ; Rigidity ; Structure analysis ; Three dimensional imaging ; Tissue engineering ; Trigonal unit cell ; Biocompatible Materials ; Computer Simulation ; Finite Element Analysis ; Materials Testing ; Models, Theoretical ; Porosity ; Stress, Mechanical ; Tissue Scaffolds
  8. Source: Journal of Biomechanics ; Volume 45, Issue 16 , 2012 , Pages 2866-2875 ; 00219290 (ISSN)
  9. URL: http://www.jbiomech.com/article/S0021-9290%2812%2900490-3/abstract