查看更多>>摘要：With the rapid development of additive manufacturing(AM),scaffold architectures based on triply periodic minimal surfaces(TPMS)have attracted increasing interest in various engineering fields.Nevertheless,they are limited because of the complexity of the design process when adopted in different research and engineer-ing fields.In this work,we present a free and easy-to-use software package called TPMS_Scaffold_Generator,which is coded using MATLAB(Mathworks,Inc.,USA).It offers three function tabs which are homogeneous tab,heterogeneous tab and multisymmetrical tab,respectively.Variables of the tabs include the volume frac-tion,topology type,unit cell size,the length of architecture in X,Y,Z direction,accuracy,and the style of gradient and so forth.TPMS_Scaffold_Generator can generate various TPMS scaffolds,especially ultralight and multisymmetrical scaffolds.The latest version of the TPMS_Scaffold_Generator is freely available at:https://github.com/LeveeLin/TPMS_Scaffold_Generator.git.
查看更多>>摘要：NiTiCu thin walls were produced by twin-wire arc additive manufacturing(T-WAAM)using commercial NiTi and Cu wires as the feedstock materials.This approach aims to solve the problems typically associated with large phase transformation hysteresis in NiTi shape memory alloys.The microstructure,mechanical properties,and phase transformation behavior of the as-deposited NiTiCu alloy were comprehensively examined.The results re-vealed that the as-deposited NiTiCu alloy was well-formed,with its microstructure showed columnar,equiaxed,and needle-like grains,depending on the location within the deposited walls.The microhardness gradually in-creased from the first to the third layer.The Cu content was 20.80 at％,and Cu-based precipitates were formed in the as-deposited NiTiCu.The volume fractions and lattice parameters of the matrix and precipitates in the as-deposited NiTiCu material were analyzed using high-energy synchrotron X-ray diffraction.The martensitic phase was identified as a B19 crystal structure,and the as-deposited NiTiCu underwent a one-step B2-B19 phase transformation.The tensile strength and fracture strain were approximately 232 MPa and 3.72％,respectively.In particular,the addition of Cu narrowed the phase transformation hysteresis of the as-deposited NiTiCu alloy from 24.4 to 7.1 ℃ compared with conventional binary NiTi alloys.This study expands the potential of T-WAAM in modifying the phase transformation behavior of NiTi-based ternary alloys.
查看更多>>摘要：Polyamide(PA)is a widely utilized engineering polymer,and its thermal and mechanical properties can be further improved by adding nanofillers.However,adding inorganic fullerene-like tungsten disulfide(IF-WS2)nanoparticles(NPs)to PA to produce composite precursor powders for additive manufacturing is challenging.Here,we report a novel and cost-effective method for fabricating PA-12 based nanocomposite(NC)powders with fixed/partially encapsulated IF-WS2 nanoparticulate fillers utilizing an advanced mixing technique because simple wet mixing(WM)can only attach fillers weakly to the powder surfaces when compared to the proposed method.The resulting nanocomposite powders maintained nearly the original particle size distribution of PA-12.They also exhibited improved rheological properties,melting,and crystallization behaviors compared with those prepared by the WM method.The laser-sintered PA-12 nanocomposite specimens revealed enhanced pow-der thermal stability and higher tensile strengths than pristine PA-12,validating the advantages of the novel technique for the fabrication of polyamide nanocomposite powders and their suitability for utilization in laser sintering additive manufacturing.These results demonstrate that high-performance engineered PA-12 nanocom-posite components can be directly laser sintered,and this technique can potentially be extended to fabricate other engineered polymeric nanocomposite powders.
查看更多>>摘要：Owing to the developments in the aerospace,semiconductor,nuclear energy,and other fields,there is an in-creasing demand for complex-shaped ceramic components with specific characteristics such as high-temperature resistance,corrosion resistance,high rigidity,and high strength.Although additive manufacturing(AM),a prime technology for manufacturing complex ceramic components,has received increasing attention from researchers and producers,AM of ceramic components faces various challenges including deformation,cracking,and signif-icant shrinkage in terms of shape,size accuracy,and performance control.These challenges significantly limit the application and development of AM.Support structures,an essential element in AM,not only ensure the for-mation of components but also play a crucial role in minimizing the shrinkage and deformation of components during the high-temperature sintering operation.In this article,commonly used support structures in current ce-ramic additive manufacturing processes are reviewed and classified into contact supports,contactless supports,support-free techniques,and combined supports.Subsequently,the relationship between ceramic AM processes and support types is discussed.Furthermore,this article summarizes the research progress in support optimization from two perspectives:printing direction and support structure optimizations.Accordingly,it proposes a support design approach from the perspective of the entire process flow and concludes by outlining future development directions in ceramic support design.
查看更多>>摘要：Printing three-dimensional(3D)scaffolds with suitable mechanical cues is an effective strategy for guiding tissue regeneration by inducing cell migration and growth.Nevertheless,many studies considered only one type of cue for 3D tissue engineering scaffold fabrication,such as topological cues,which is insufficient.To realize durotaxis-and topotaxis-orchestrated guidance on cell migration,a 3D printed scaffold/hydrogel composite was fabricated in this study.The porous scaffold provided a topological cue(topotaxis),and the combined hydrogel provided a compliance cue(durotaxis).The results indicated that the thin fibers of the scaffold induced cell migration,and the larger pore size and directed fiber number of the scaffold led to more uniform cell orientation(topotaxis).Furthermore,when collagen was cured to cover the scaffold to result in a compliance change,the cells in the collagen still sensed the scaffold topological cue and migrated along it(durotaxis).Collagen also provides a living space and nutrition for cells,thereby significantly increasing their number.The effects of durotaxis and topotaxis synthesis provide a promising solution for tissue engineering scaffold applications.
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