Analysis On The Mechanical Behaviors And Permeability Of Triply Periodic Minimal Surfaces Based Scaffolds

Bone tissue engineering is a promising technology in the treatment of segmental bone defect.Bone scaffold,which is an important basic element in bone tissue engineering,can provide the structural support while facilitating the growth of bone tissue.Generally,scaffolds can be formed by assemblying one or several types of basic unit cell models in a periodic way.Therefore,the performance of scaffolds is largely influenced by the type of the unit cell and and its microstructure.The triply periodic minimal surfaces(TPMS)based scaffolds possess similar microstructure as the natural human bones.Therefore,understanding the mechanical biological behaviors of TPMS scaffolds can provide important values for the design of scaffolds.In the present study,five TPMS(Diamond,Gyroid,Schwarz P,F-RD,Fischer-Koch S)and three traditional lattice structures(Cube,FD-Cube,Octa)were selected.The relationship between the mechanical properties(effective compressive and shear moduli)and the porosity were investigated using the finite element method.Additionally,the anisotropic elastic mechanical behaviors of TPMS scaffolds were analysed using the analytic method and the representative volume element(RVE)method.The results showed that when the scaffold porority increased,the equivalent elastic modulus of the scaffolds in the loading axis decreased,but the permeability of the scaffolds increased.The anisotropic analysis showed showed that when the scaffold porosity increased,the anisotropic properties of the scaffolds increased.Additionly,when the scaffolds were subjected to uniaxial compression loading,a higher compression resistance was achieved in the stretch-dominated scaffolds.When the fluid channels in the scaffolds were consistent with the direction of the seepage flow,the permeability of the scaffolds was higher.In the present study,it is revealed that the mechanical and biological properties of the scaffolds can be tuned by the scaffold porosity.The increase of scaffold permeability always lead to the decrease of the mechanical properties of scaffolds.The performance of scaffolds is largely influenced by the microstructure of the scaffolds.These findings can be used to facilitate the design of bone scaffolds.