Bionic Design And Optimization Of Personalized Tissue Engineering Bone Scaffold

The engineering bone scaffold is the most ideal substitute for human bone defect at present.It is of great economic and practical significance for clinical treatment of bone defects.However,the problems of low imitation degree,poor biological activity and mismatch with the mechanical properties of the tissue to be implanted still exist in the use of the tissue engineering bone scaffold at present.Therefore,based on the principle of bionics,basic unit cells with gradual structures are designed according to the microporous structure of natural load-bearing bone.On this basis,the mechanical and permeability properties of the basic unit cells are analyzed and studied by ADINA.And two kinds of methods are put forward to combine the internal microstructures with the external contour of the bionic bone.The main research works are as follows:(1)To solve the defects existed in the design of microstructure of bionic bone,such as unitary pore structure,poor connectivity and so on.Based on the principle of bionic design,three types of new basic unit cells with gradual structures are designed according to the internal microstructure of natural load-bearing bone.On the basis of the three new basic unit cells,the design parameters are optimized with the objective of the mechanical properties of human load-bearing bone by ADINA.The results show that the design parameters of basic unit cells have a certain effect on its porosity and elastic modulus,and the elastic modulus decreases with the increase of porosity.The optimized three basic unit cells can meet the needs of porosity(5%~90%)and elastic modulus(10~30GPa)of human load-bearing bone,which can be applied to the design of load-bearing bone scaffold.(2)Based on mechanical properties of the basic unit cells,the hydrodynamic environment of the micropore structure in the bone scaffold is studied by computational fluid dynamics method.Secondly,the k values of the specific permeability of the basic unit cells are obtained according to Darcy's law.The results show that the permeability of the basic unit cells obtained by Darcy's law is in good agreement with the conclusion obtained by CFD simulation of the hydrodynamic environment in micropore structure of basic unit cells.It is found that the open rod unit cell has the best fluid transport performance by comparing and analyzing the hydrodynamic environment and specific permeability k in different unit cells.(3)Based on finite element shape function mapping method and constructive solid geometry theory,two bone scaffold modeling methods are proposed to combine the internal microstructures with the external contour of bionic bone.The first one is based on manual assembly,and the second one is based on shape function and hexahedral division.For the above two methods,the specific modeling ideas and examples are given,and the automatic generation program of scaffold is developed by using UG/open grip language for the second bone scaffold modeling method.The results show that the modeling method based on shape function and hexahedral division has the advantages of fast modeling efficiency,good controllability and high profile accuracy.It lays foundation for the bionic design and rapid prototyping manufacture of tissue engineering bone scaffold.