Design Optimization For Open-Porous Scaffolds Of Tissue Engineering And Manufactured By SLM

With the acceleration of population aging,developing the match the human bone of porous implants is particularly important.Solid metal implants easily lead to patient discomfort with larger weight and stiffness,and cause loose easily because there is not enough interlocking fixed between the solid implant and the host bone,leading to implant life cut back.In order to obtain a better biomechanical model,the surface or all of the model of the metal implant can be designed as a porous structure,and parametric customization with the different parts of the structure and mechanical.But the traditional method cannot process inside the complex porous structure.With the development of 3D printing technology,the problem was solved gradually.3D printing is a manufacturing technology which is based on the digital model,through the material layer by layer into a solid.Selective Laser Melting(SLM)is one of 3D printing technology.The technology is used for making metal parts with high precision and is applied widely which also can be used for the preparation of internal pore structure and fine small geometric features.This paper proposes two kinds methods of designing porous scaffolds which can meet the optimal pore size,porosity and mechanical properties of tissue scaffold regeneration.And the mechanical properties were studied by finite element method.The influence of process parameters on the quality of the parts are analyzed.Finally,the compressive properties of the porous scaffolds were analyzed.The contents and conclusions are introduced as follows:(1)This paper presents a relatively simple controllable porous structure design method.The method of designing a controllable porous structure of a wire-to-body,which allows the volume of different porous structures to be obtained by controlling the thickness of the wire,and to obtain porous scaffolds with different porosities.(2)Through the simulation,it is found that the elastic modulus and the yield strength increase with the increase of the thickness increasing when the pore size of the same unit are the same.When the thickness is the same,the elastic modulus and the yield strength decrease with the pore size increasing.And the same unit cells,the elastic modulus and yield strength of decrease with the increase of porosity.The stress at the junction of between the strut and the strut is large,and the stiffness of the scaffolds can be increased by varying the connection thickness of the struts.And the validity of the simulation results is verified by experiments.(3)Based on the density method,the topology optimization model of unit cell is established to achieve the maximum stiffness mechanical properties.Under the constraint of volume fraction,the topology optimization design was carried out,and the microstructures with the maximum stiffness under fixed volume fraction were obtained.The compressive strength and elastic modulus of the scaffolds with 60%,70%,80%,90%(volume fraction of 40%,30%,30%,10%)were obtained by compression test whose elastic modulus and compressive strength values are within the scope of the requirements of the bones.