Predicting the Elastic Properties of Selective Laser Sintered PCL/β-TCP Bone Scaffold Materials Using Computational Modelling

Abstract

Publication InformationDoyle, H., Lohfeld, S., McHugh, P.E. (2013) 'Predicting the elastic properties of selective laser sintered PCL/b-TCP bone scaffold materials using computational modelling'. Annals Of Biomedical Engineering, 42 (3):661-677. Publisher SpringerLink to publisher's version http://link.springer.com/article/10.1007%2Fs10439-013-0913-4Item record http://hdl.handle.net/10379/5524 DOI http://dx.doi.org/10.1007/s10439-013-0913-4Accepted manuscript, published in Annals of Biomedical Engineering 09/2013; 42(3), pp 661-677. The final publication is available at Springer via http://dx.doi.org/10.1007/s10439-013-0913-4Title: Predicting the elastic properties of selective laser sintered PCL/β-TCP bone scaffold materials using computational modelling. AbstractThis study assesses the ability of finite element models to capture the mechanical behaviour of sintered orthopaedic scaffold materials. Individual scaffold struts were fabricated from a 50:50 wt% poly-ε-caprolactone (PCL) /β-tricalcium phosphate (β-TCP) blend, using selective laser sintering (SLS). The tensile elastic modulus of single struts was determined experimentally. High resolution finite element models of single struts were generated from micro-CT scans (28.8µm resolution) and an effective strut elastic modulus was calculated from tensile loading simulations. Three material assignment methods were employed: (1) homogeneous PCL elastic constants, (2) composite PCL/ β-TCP elastic constants based on rule of mixtures, and (3) heterogeneous distribution of micromechanically-determined elastic constants. In comparison with experimental results, the use of homogeneous PCL properties gave a good estimate of strut modulus; however it is not sufficiently representative of the real material as it neglects the β-TCP phase. The rule of mixtures method significantly overestimated strut modulus, while there was no significant difference between strut modulus evaluated using the micromechanically-determined elastic constants and experimentally evaluated strut modulus. These results indicate that the multi-scale approach of linking micromechancial modelling of the sintered scaffold material with macroscale modelling gives an accurate prediction of the mechanical behaviour of the sintered structure.Keywords: selective laser sintering; polycaprolactone, B-tricalcium phosphate; micromechanical modelling; bone tissue engineering; mechanical properties; finite element analysis.3 IntroductionThe purpose of bone tissue engineering scaffolds is to fill defects and support mechanical loading while providing a template on which new bone will form. The remodelling of native bone in response to mechanical loading occurs when cells convert mechanical stimuli to chemical signals to direct the formation of new tissue or resorption through mechanotransduction 30,44 . The mechanical stimuli that influence bone formation in vivo are a combination of both fluid shear over the cells 36,55 and mechanical loading of the cells 16,24,58 , therefore it is important to be able to acc...

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