Gyroid Structure Research Articles

Study on the topological morphology and mechanical properties of variable-amplitude TPMS structures

TPMS structures possess immense potential in terms of lightweight and multifunctional applications. However, previous studies have predominantly focused on aspects such as wall thickness, unit cell size, periodicity, and level set values. The impact of amplitude factors on the topological shape and mechanical properties of TPMS has not been fully elucidated. Here, primitive (P), gyroid (G), and diamond (D) structures were initially examined to explore the effects of amplitude factors on the topological shape and relative density of TPMS structures. The mechanical properties and energy absorption capability of the variable amplitude structures were investigated, with emphasis on a gyroid structure, using both experiments and numerical simulations. It was found that the amplitude does not alter the deformation pattern of the structure. However, the mechanical properties of the structure can be regulated over a relatively large range. Specifically, the elastic modulus and yield strength at an amplitude of 1.6 were observed to be approximately 1.5 times those at an amplitude of 0.4, and the plateau stress was approximately 1.33 times that of 0.4. Additionally, with increasing amplitude factor, there was a slight decrease in the densification strain of the structure but a significant increase in its energy absorption capability. Such findings offer a novel means by which the mechanical properties of TPMS structures can be modulated, providing new opportunities for the development of tissue scaffolds or energy-absorbing devices.

Mechanical properties of graphene-based gyroidal sheet/shell architected lattices

AbstractCreating 3D cellular structures out of 2D nanomaterials such as graphene is an active area of research since most realistic applications require multi-functional 3D objects. Graphene aerogels that are taking the topology of stochastic foam microstructures have been extensively studied. Additive manufacturing has shifted the focus from stochastic aerogels to architected 3D graphene lattices (3DGL). In this paper and for the first time, we synthesized, characterized, and mechanically tested 3DGLs with microstructures taking the topology of shell-based gyroid structure and compared their properties to tubular 3DGL. 3DGLs were fabricated using a hydrothermal-assisted dip-coating method based on 3D-printed polymer templates. Effects of number of unit cell, graphene oxide (GO) concentration, and polymer template volume fraction have been investigated. It was found that smaller polymer template volume fraction, smaller unit cell, and larger GO concentration lead to increased mechanical properties. It was found that the mechanical properties of the synthesized gyroid shell-based 3DGLs outperformed tubular and 3DGLs and stochastic graphene aerogels. Furthermore, both gyroidal shell and tubular 3DGLs exhibit stretching-dominated behavior making them ideal for synthesizing stiffer and stronger graphene lattices. This study serves as a guideline for designing multi-functional shell-based lattices made of 2D materials with enhanced mechanical properties for various applications.

Investigation of micro lattice spiral wound membrane structures availing DLP and FDM techniques for water treatment

This study addressed the challenge of reducing water contaminants using Spiral Wound Membrane (SWM) units in desalination and water treatment. Through additive manufacturing, we developed complex micro-lattice feed-spacer structures using FlexBLK 20, Pro-BLK10, ToughBLK 20, PLA, PETG, and ABS materials. The AHPTOPSIS statistical method indicated an ideal solution with Digital Light Processing (DLP) conditions showing a 20 μm layer thickness, FlexBLK-20 material, diamond structure, and for Fused Deposition Modeling (FDM) conditions, a 0.1 mm layer thickness, PLA material, and gyroid structure. Significant findings include a decrease in surface roughness by 79.67%–85.25% for DLP, an elongation increase of 50%–91.67%, and tensile strength improvement between 0.07%–40.83%. DLP printed feed spacers showcased better surface distributions than FDM, attributed to finer layers and higher density printing. Additionally, DLP printing resulted in a 32.02% increase in residual stress, suggesting superior compressive resistance. In thermal analyses, both DLP and FDM materials showed thermal stability up to 380 °C–450 °C. This research indicates that DLP printed feed spacers, with their enhanced properties, are potentially more efficient for water purification systems, providing smoother surface, better filtration, and increased durability.

Stability of Hierarchical Gyroid Structures in Frustrated ABC Triblock Copolymers

Stability of Hierarchical Gyroid Structures in Frustrated ABC Triblock Copolymers

Digital Manufacturing of Functional Ready-to-Use Microfluidic Systems.

Digital manufacturing (DM) holds great potential for microfluidics, but requirements for embedded conduits and high resolution beyond the capability of common manufacturing equipment, and microfluidic systems' dependence on peripheralshave limited its adoption. Capillaric circuits (CCs) are structurally encoded, self-contained microfluidic systems that operate and self-fill via precisely tailored hydrophilicity. CCs are heretofore hydrophilized in a plasma chamber, but which offers only transient hydrophilicity, lacks reproducibility, and limits CC design to open surface channels subsequently sealed with tape. Here, the additive DM of monolithic, fully functional, and intrinsically hydrophilic CCs is reported. CCs are 3D printed with commonly available light-engine-based 3D printers using poly(ethylene glycol)diacrylate-based ink co-polymerized with hydrophilic acrylic acid crosslinkers and optimized for hydrophilicity and printability. A new, robust capillary valve design and embedded conduits with circular cross-sections that prevent bubble trapping are presented, interwoven circuit architectures created, and CC use illustrated with an immunoassay. Finally, the external paper capillary pumps are eliminated by directly embedding the capillary pump in the chip as a porous gyroid structure, realizing fully functional, monolithic CCs. Thence, a digital file can be made into a CC by commonly available 3D printers in less than 30min enabling low-cost, distributed DM of fully functional ready-to-use microfluidic systems.

Plasma surface modification and three‐dimensional structuring of additively manufactured polyetheretherketone implants for improvement of osseointegration

AbstractOsseointegration is highly desirable for implants used for bone replacement. Polyetheretherketone (PEEK) is an attractive material due to its characteristics such as high biocompatibility and Young's modulus similar to human bones. However, PEEK is bioinert, meaning cells do not adhere and proliferate on its surface. This problem is addressed in this study, with the goal of enhancing osseointegration of additively manufactured PEEK. The influences of surface modifications and porous structures on cellular behavior were assessed by wettability and in vitro tests with subclone of the human osteosarcoma cell line‐2 osteoblasts. Overall, the combination of surface modification, type of plasma process used, atmospheric pressure versus vacuum‐based, and surface structuring, especially gyroid structures, improve the cellular proliferation on PEEK. Therefore, its ability to enhance osseointegration is highly promising.

An ultrabroadband metamaterial absorber based on remarkable magnetic coupling via constructing conductive composite resonators and magnetic gradient gyroid structure

ABSTRACT Broadband electromagnetic absorbing is still a challenge due to the huge difference of waves properties in different frequency bands. Herein, based on the transmission-line theory, we propose an in-plane hybrid metamaterial absorber using coupled resonators and gradient gyroid structure to realise the ultrabroadband absorbing. The coupled resonators based on Ag–Cu alloy/ABS conductive composite serve as transmission lines to orient the dipolar magnetic field, while the gradient gyroid structure fabricated by FCI/PEEK composite boosts the strong induced magnetic field. The unique hybrid strategy contributes to the remarkable magnetic coupling interaction, which not only realises good bandwidth extending effect, but also demonstrates the enhancement of absorbing efficiency. Finally, the 3D-printed hybrid metamaterial absorber achieves the high-efficiency absorbing in 2.2–40 GHz due to the electromagnetic field coupling resonance and synergistic loss effect. This absorber shows promising potential in real-life application by reasons of the low-frequency broadband absorption and convenient manufacturing.

Influence of structural parameters of 3D-printed triply periodic minimal surface gyroid porous scaffolds on compression performance, cell response, and bone regeneration.

In this study, multi-scale triply periodic minimal surface (TPMS) porous scaffolds with uniform and radial gradient distribution on pore size were printed based on the selective laser melting technology, and the influences of porosity, pore size and radial pore size distribution on compression mechanical properties, cell behavior, and bone regeneration behavior were analyzed. The results showed that the compression performance of the uniform porous scaffolds with high porosity was similar to that of cancellous bone of pig tibia, and the gradient porous scaffolds have higher elastic modulus and compressive toughness. After 4 days of cell culture, cells were distributed on the surface of scaffolds mostly, and the number of adherent cells was higher on the small pore size porous scaffolds; After 7 days, the area and density of cell proliferation on the scaffolds were improved; After 14 days, the cells on the small pore size scaffolds tended to migrate to adjacent pores. Animal implantation experiments showed that collagen fiber osteoid was intermittent on scaffolds with high porosity and large pore size, which was not conducive to bone formation. The appropriate pore size and porosity of bone regeneration were 792 um and 83%, respectively, and the regenerative ability of gradient pore size was better than that of uniform pore size. Our study explains the rules of TPMS gyroid structure parameters on compression performance, cell response and bone regeneration, and provides a reference value for the design of bone repair scaffolds for clinical orthopedics.

Eklemeli imal edilmiş gözenekli topolojilerin ısıl performansı üzerine deneysel incelemeler

Additive manufacturing enables researchers to form unique and unconventional topologies satisfying design compactness, improved efficiency, and lower cost. Design freedom introduced by the additive manufacturing reveals the idea of implementing the topology optimization approach into thermal systems. In this study, changes in thermal performance of three types of topologies: gyroid, hexagon (honeycomb), and rectilinear are experimentally investigated. In addition, porosity level of each topology is varied in between 25%, 50% and 75% to improve the impact of the study. The experimental results indicate that gyroid structures are thermally more efficient (up to 15.6%) than the remaining topologies. Furthermore, thermal diffusivities of the rectilinear and gyroid topologies with 25% porosity level are measured as the extremes, and it is detected that these structures propagate heat 1.1 times greater than the hexagon structure.

Compression and resilient behavior of graded triply periodic minimal surface structures with soft materials fabricated by fused filament fabrication

Additive manufacturing is an effective method to realize complex biomimetic topology and tunable mechanical property. In the current work, to meet the requirements of damping buffers and energy absorbers, triply periodic minimal surface (TPMS) structure using two soft polymeric blends as feedstock materials were gradient design and manufactured via fused filament fabrication. The internal topography of Schwarz P, Gyroid and Diamond TPMS structures were observed by scanning electron microscope and micro-computed topography. The compressive test results demonstrated that Diamond possessed superior load-carrying and energy absorption capacity to Gyroid and Schwarz P structure. The energy absorption for graded Diamond and Gyroid structures were better than the uniform controls, whereas Schwarz P displayed an opposite trend. Meanwhile, less internal damage and good resilient behavior were observed for polymeric blends with better resistance to plastic deformation. Lastly, cycle loadings were conducted, and the elastic energy, consumed energy as well as the specific damping capacity for graded and uniform TPMS soft structures were explored. With the increase of loading cycles, the Diamond TPMS structure exhibited a better damping behavior whereas Schwarz P displayed an elastic behavior. The elastic deformation was gradually replaced by the inelastic deformation of energy consumption and dissipation.

Effect of Porosity and Pore Shape on the Mechanical and Biological Properties of Additively Manufactured Bone Scaffolds.

This study investigates the effect of porosity and pore shape on the biological and mechanical behavior of additively manufactured scaffolds for bone tissue engineering (BTE). Polylactic acid scaffolds with varying porosity levels (15-78%) and pore shapes, including regular (rectangular pores), gyroid, and diamond (triply periodic minimal surfaces) structures, are fabricated by fused filament fabrication. Murine-derived macrophages and human bone marrow-derived mesenchymal stromal cells (hBMSCs) are seeded onto the scaffolds. The compressive behavior and surface morphology of the scaffolds are characterized. The results show that scaffolds with 15%, 30%, and 45% porosity display the highest rate of macrophage and hBMSC growth. Gyroid and diamond scaffolds exhibit a higher rate of macrophage proliferation, while diamond scaffolds exhibit a higher rate of hBMSC proliferation. Additionally, gyroid and diamond scaffolds exhibit better compressive behavior compared to regular scaffolds. Of particular note, diamond scaffolds have the highest compressive modulus and strength. Surface morphology characterization indicates that the surface roughness of diamond and gyroid scaffolds is greater than that of regular scaffolds at the same porosity level, which is beneficial for cell attachment and proliferation. This study provides valuable insights into porosity and pore shape selection for additively manufactured scaffolds in BTE.

Design and performance of a novel neutron shielding composite materials based on AlSi10Mg porous structure fabricated by laser powder bed fusion

Available neutron shielding materials have shortcomings. In order to obtain a neutron shielding composite materials with good shielding performance, excellent mechanical property and strong designability, this study used laser powder bed fusion technology to form a porous structure of AlSi10Mg as a frame, and made a novel neutron shielding composite materials by adding epoxy resin/B4C mixed materials through negative pressure perfusion. The Gyroid structure of triply periodic minimal surface (TPMS) was used as the frame structure, and four different porosity ratios of 50%, 60%, 70% and 80% were designed. After morphological characterization and mechanical simulation, the frame structure was filled with epoxy resin/B4C mixed materials, and then compression test and shielding test were conducted respectively. Its compressive strength ranged from 39.16 to 135.6 MPa, and its shielding coefficient was found to be in the range of 2.98–4.09 cm−1. The results showed the compressive strength and shielding coefficient under different porosity frames, which could provide a reference for designing and applying new neutron shielding composite materials in the nuclear industry.

Inverse design of multi-material gyroid structures made by additive manufacturing

Additively manufactured gyroid structures have great potential in lightweight structure design, energy absorption, heat transfer, and biomedical applications. The optimization and design of the relative density of gyroid structures have been studied for a decade but mainly focusing on a single material phase. Multi-material Additive Manufacturing brought out the material complexity in structures, which extended the design parameter for gyroid structures from relative density to material distribution. In this research, a data-driven inverse design model was developed for multi-material gyroid structures using machine learning. The structures were fabricated by the material extrusion process with a combination of PLA and TPU materials. The mechanical properties of these structures were studied by compression tests and polynomial interpolations. It was found that the interpolation method can accurately indicate the relationship between relative density, material ratio, and mechanical properties. The interpolation functions were used to randomly generate the training data for machine learning. A well-trained neural network model was developed to find the inverse relationship between the mechanical properties and the design parameters. It is used in the design process to determine the relative density and PLA/TPU ratio by the elastic modulus, energy absorption, and peak stress. Subsequent validation experiments verified the efficacy of the proposed design model, demonstrating its ability to accurately predict the desired properties using the machine learning framework. Consequently, this innovative approach has substantially reduced the complexities associated with designing multi-material gyroid structures.

Vat photopolymerization 3D printing gyroid meta-structural SiOC ceramics achieving full absorption of X-band electromagnetic wave

The concept of 3D printing metamaterials to produce structure-function integrated absorbing ceramics has attracted great attention. However, there is still a lack of guidance on how to design meta-structures to achieve the preparation of excellent electromagnetic (EM) absorbers. Herein, a kind of ultraviolet (UV)-curable polysiloxane (PSO) resin slurry was successfully designed. According to the results of CST simulation, the gyroid structure (GS) with good formability and high ceramic yield was obtained by vat photopolymerization (VPP). After pyrolyzed at 1100–1300 °C, the GS SiOC metamaterials with a density of 1.430 ∼ 1.612 g·cm−3 have the minimum reflection loss (RLmin) of −59.96 dB at 2.90 mm and effective absorption bandwidth (EAB) of 4.20 GHz (8.2–12.4 GHz) at the thickness of 2.69–3.15 mm, covering the whole X-band EM wave. Moreover, the simulated reflection loss (RL) results of the GS metamaterials are consistent with the experimental values at different thickness. This strategy realizes the integration of simulation, modeling, experiment of EM absorbing metamaterials, and provides a new idea for the development of ceramic-based high temperature absorbing materials.

Three-dimension dithering and its effect on the interfacial strength of multi-material and emulated multi-material additive manufacturing processes

Multi-Material Additive Manufacturing (MMAM) offers the potential for superior functional parts by varying properties throughout a structure. Previous work has shown that the interface region of such MMAM parts has great importance on their overall strength. Most of these studies have focused on rigid–compliant interfaces within parts manufactured via material jetting (MJT). This work focuses, initially, on the creation of different interfacial geometries within functionally graded tensile bars by extending two dimensional dithering algorithms from the realm of image processing into the third dimension. It tests these dithered patterns, along with Schwarz P and Gyroid structures, across rigid–complaint MJT interfaces before further exploring the previously unaddressed question of how these different geometries affect interfacial strength across rigid–rigid interfaces for both UV cured materials, via MJT, and thermoplastic materials, via a new prototype electophotographic toner-based AM system. Within the MJT parts, the samples often failed inside the large regions of the more compliant material rather than at the interface itself. In addition, the interfacial length is shown to have more effect on the mechanical properties compared to interface pattern. However, the thermoplastic samples consistently failed within the interface region. The toughness of these thermoplastic parts increased with an increase in the connected surface area in the tensile direction between the largest regions of each of the two materials, with three dimensional random dithering over a 20 mm gradient length exhibiting the toughest interface overall (40.8% increase in the work at break when compared to a control sample with no special interfacial geometry). This work, therefore, provides a new emphasis to explore, within the context of the design of thermoplastic multi-material interfaces, geometries that increase this connected surface area.

In-plane measurements and computational fluid dynamics prediction of permeability for biocompatible NiTi gyroid scaffolds fabricated via laser powder bed fusion

Laser powder bed fusion (LPBF) is considered a promising technology for manufacturing porous, biomimetic, and patient-specific scaffolds for bone repair. Scaffold permeability is one of the key factors to be considered for acquiring the required mass-transport properties in bone tissue engineering. This study aims to reveal the relationship between the design parameters of gyroid-based porous structure and scaffold permeability. A set of gyroid samples was manufactured from intermetallic NiTi alloy. Nine configurations of porous structures were obtained by varying the main design parameters, namely wall thickness and unit cell size. The in-plane method was employed to measure the permeability coefficient for the gyroid structures. Computational fluid dynamics simulations of the porous structures were performed to predict the targeted properties in an implant at the design stage before LPBF manufacturing. The results of the simulations were validated with the obtained experimental results. Geometrical accuracy and surface morphology of the as-built samples were investigated with various techniques. Biocompatibility assessment of the gyroid scaffolds was performed with human cell culture experiments. 

Static compression and fatigue behavior of heat-treated selective laser melted titanium alloy (Ti6Al4V) gyroid cylinders

Porous additively-manufactured structures could have a niche in orthopaedic implants, due to their potential to reduce stiffness (stress-shielding), improve bony ingrowth, and potential to house reservoirs of drug-eluting non-structural biomaterials. Computer aided design and finite element (FE) modelling plays an important role in the design of porous structured biomedical implants; however it is important to validate both their static and fatigue behaviours using experimental testing. This study compared the mechanical behaviors of titanium cylindrical gyroid structures of varying porosities using physical testing of additively manufactured prototypes and FE models. There was agreement in the measured and predicted relationships between porosity and apparent modulus of elasticity. As porosity increased (and wall thickness decreased), the structures failed at a lower number of cycles when loaded at the same percentage of their yield strengths. Calibration of the fatigue strength coefficient from a previously published value of 1586.5 MPa–1225 MPa greatly improved the fatigue life prediction accuracy for all the gyroid structures. Nevertheless, differences of up to 54% in the predicted versus experimental fatigue lives remained, which could be attributed to difficulties with how the precise time and location of failure is defined in the simulations, and/or minor differences in nominal and actual porosities. Although further calibration and validation should be explored, this study demonstrates that static and fatigue FE-modelling techniques could be used to aid in the design of porous prosthetics.

Evaluating 3D-printed bioseparation structures using multi-length scale tomography

X-ray computed tomography was applied in imaging 3D-printed gyroids used for bioseparation in order to visualize and characterize structures from the entire geometry down to individual nanopores. Methacrylate prints were fabricated with feature sizes of 500 µm, 300 µm, and 200 µm, with the material phase exhibiting a porous substructure in all cases. Two X-ray scanners achieved pixel sizes from 5 µm to 16 nm to produce digital representations of samples across multiple length scales as the basis for geometric analysis and flow simulation. At the gyroid scale, imaged samples were visually compared to the original computed-aided designs to analyze printing fidelity across all feature sizes. An individual 500 µm feature, part of the overall gyroid structure, was compared and overlaid between design and imaged volumes, identifying individual printed layers. Internal subvolumes of all feature sizes were segmented into material and void phases for permeable flow analysis. Small pieces of 3D-printed material were optimized for nanotomographic imaging at a pixel size of 63 nm, with all three gyroid samples exhibiting similar geometric characteristics when measured. An average porosity of 45% was obtained that was within the expected design range, and a tortuosity factor of 2.52 was measured. Applying a voidage network map enabled the size, location, and connectivity of pores to be identified, obtaining an average pore size of 793 nm. Using Avizo XLAB at a bulk diffusivity of 7.00 × 10−11 m2s−1 resulted in a simulated material diffusivity of 2.17 × 10−11 m2s−1 ± 0.16 × 10−11 m2s−1.Graphical abstract

Numerical study on the anisotropy in thermo-fluid behavior of triply periodic minimal surfaces (TPMS)

Porous structures are frequently utilized as thermal conductivity enhancers in the realm of heat transfer enhancement. Triply Periodic Minimal Surface (TPMS) has gained significant attention in recent years due to its favorable performance in many fields including mechanics and thermodynamic. The exceptionally large specific surface area grants it promising performance in heat transfer enhancement. However, the angular effect on thermal-fluid characteristics are not understood and requires further investigation. In this work, Gyroid and Diamond with various rotating angles used as sandwich cores were designed utilizing the implicit function method. Then, the discussions on thermal and hydraulic behaviors in the TPMS-based sandwich panels under an isothermal condition were systematically conducted by means of computational fluid dynamics. After that, the fluid flow mechanisms and heat transfer properties were visually investigated according to the comparative analysis of velocity fields, pressure drops, vortices inducing, and Nusselt number distribution. The results showed that the flow field characteristics and the heat transfer performance exhibited an apparent 45° symmetry in both Gyroid and Diamond. Moreover, the pressure gradient exhibited evident dependence on the rotating angle in both Gyroid and Diamond groups. The 45° rotated Gyroid structure case had the most extensive pressure gradient of 11.4 kPa/m; to the contrary, the 45° rotated Diamond structure had the smallest one of 9.9 kPa/m in their respective group. Nonetheless, the angular difference in heat transfer rate (HTR) is not significant, and the maximum total HTR in Gyroid and Diamond groups was 8.25 W and 9.43 W, respectively. Overall, this work contributes to a better understanding of the angular behavior of TPMS-based sandwich panels and provides valuable information for their potential applications in various industries.

Deconvolution volumetric additive manufacturing

Volumetric additive manufacturing techniques are a promising pathway to ultra-rapid light-based 3D fabrication. Their widespread adoption, however, demands significant improvement in print fidelity. Currently, volumetric additive manufacturing prints suffer from systematic undercuring of fine features, making it impossible to print objects containing a wide range of feature sizes, precluding effective adoption in many applications. Here, we uncover the reason for this limitation: light dose spread in the resin due to chemical diffusion and optical blurring, which becomes significant for features ⪅0.5 mm. We develop a model that quantitatively predicts the variation of print time with feature size and demonstrate a deconvolution method to correct for this error. This enables prints previously beyond the capabilities of volumetric additive manufacturing, such as a complex gyroid structure with variable thickness and a fine-toothed gear. These results position volumetric additive manufacturing as a mature 3D printing method, all but eliminating the gap to industry-standard print fidelity.