Triply Periodic Minimal Surface Structures Research Articles

Mechanical evaluation of elastomeric thermoplastic polyurethane additively manufactured triply periodic minimal surface area lattice structures for adjustable cushioning properties

Purpose Cushioning is a useful material property applicable for a range of applications from medical devices to personal protective equipment. The current ability to apply cushioning in a product context is limited by the appropriateness of available materials, with polyurethane foams being the current gold standard material. The purpose of this study is to investigate additively manufactured flexible printing of scaffold structures as an alternative. Design/methodology/approach In this study, this study investigates triply periodic minimal surface (TPMS) structures, including Gyroid, Diamond and Schwarz P formed in thermoplastic polyurethane (TPU), as a possible alternative. Each TPMS structure was fabricated using material extrusion additive manufacturing and evaluated to ASTM mechanical testing standard for polymers. This study focuses attention to TPMS structures fabricated for a fixed unit cell size of 10 mm and examine the compressive properties for changes in the scaffold porosity for samples fabricated in TPU with a shore hardness of 63A and 90A. Findings It was discovered that for increased porosity there was a measured reduction in the load required to deform the scaffold. Additionally, a complex relationship between the shore hardness and the stiffness of a structure. It was highlighted that through the adjustment of porosity, the compressive strength required to deform the scaffolds to a point of densification could be controlled and predicted with high repeatability. Originality/value The results indicate the ability to tailor the scaffold design parameters using both 63A and 90A TPU material, to mimic the loading properties of common polyurethane foams. The use of these structures indicates a next generation of tailored cushioning using additive manufacturing techniques by tailoring both geometry and porosity to loading and compressive strengths.

Thermal-hydraulic performance of modified Schwartz-Diamond solid-networks triply periodic minimal surface structures

The triply periodic minimal surface (TPMS) structures are widely used as disturbance core structure in high performance heat exchangers. In this paper, four modified Schwartz-Diamond solid-networks (SD-solid) TPMS structures, one structure compressed along the flow direction (β = 2), and three structures compressed along the spanwise direction (α = 2, α = 3, and α = 4) are designed. Flow and heat transfer processes in the structures are studied with computational fluid dynamics (CFD) and experimental method. The performance enhancement criterion (PEC) is employed to evaluate the overall heat transfer performance. As the results of simulation, the overall heat transfer coefficient (hoverall) of α = 2, α = 3, and α = 4 is 10.04 %, 34.34 %, and 62.03 % higher than that of SD-solid respectively. The PEC of α = 2, α = 3, and α = 4 structures is 27.35 %, 34.17 %, and 34.95 % higher than that of the original SD-solid structure, respectively. Two samples of them (β = 2 and α = 2) are fabricated using additive manufacturing and their thermal–hydraulic performance is experimented on a flow and heat transfer experimental platform. Comparing the experimental results of the hoverall, the β = 2 structure is 68.5 % higher and the α = 2 structure is 23.06 % higher than the original SD-solid structure. However, for the average pressure drop, the β = 2 structure is 448.5 % higher and the α = 2 structure is 66.77 % lower than the original SD-solid structure. It is proved that the modified SD-solid structure compressed along the spanwise direction has the performance of enhancing heat transfer and reducing the pressure drop.

Enhanced convective heat transfer in new triply periodic minimal surface structures: Numerical and experimental investigation

Triply Periodic Minimal Surfaces (TPMS) structures are increasingly recognized for their potential in thermal management due to their unique repetitive and interconnected minimal surfaces. However, a major challenge lies in enhancing the convective heat transfer performance of TPMS structures. This study introduces new TPMS designs and evaluates their thermal characteristics against established structures such as Diamond, Gyroid, SplitP, and Lidinoid employing a combination of numerical simulations and experimental measurements. The results reveal that the newly TPMS designs significantly outperform existing ones in terms of heat transfer performance. Numerically, the new TPMS structures demonstrate improvements in the Nusselt number and convective heat transfer coefficient, ranging from 6% to 13.7% and 4.6% to 20%, surpassing Lidinoid and SplitP, and eclipsing Diamond and Gyroid by 15% to 58% and 37% to 91%, respectively. Experimentally, these findings are complemented with the newly TPMS structures showing increases in convective heat transfer coefficients up to 68% and a 57% rise in Nusselt numbers compared to the Gyroid structure. These enhancements are attributed to their larger fluid-solid contact areas and optimized fluid distribution. However, a trade-off is observed in the form of increased pressure drops in the more complex TPMS structures, particularly in structures with larger circumferences and periodicities. The study also highlights the complex dynamic flow patterns within these structures, establishing a direct link between design complexity and fluid dynamics. This interconnectedness is pivotal for future design optimizations aimed at improving thermal performance. These findings represent a significant step forward in TPMS research, paving the way for further investigations into optimizing these structures for superior heat transfer performance.

Rotating Flow and Heat Transfer Characteristics of a Novel Cooling Channel for Gas Turbine Blade Trailing Edge With Diamond-Type TPMS Structures

Abstract This work designs a Diamond-type triply periodic minimal surface (TPMS) structure that exhibits excellent thermomechanical properties in a gas turbine blade trailing edge to enhance thermal performance and improve heat transfer uniformity. Since the velocity and temperature distributions are altered in the rotating trailing edge channel, the flow and heat transfer characteristics of the baseline pin fin and Diamond TPMS models are numerically investigated at the Reynolds number of 10,000 and the rotation numbers of 0.0–0.28. Compared to the baseline model, the Diamond TPMS network significantly decreases recirculation flow at the inner wall, improving heat transfer, especially at the tip and outlet regions. Although the Diamond TPMS model incurs substantial pressure losses from 191% to 234%, it yields significantly higher overall heat transfer than the pin fins by 179%. Consequently, the thermal performance increased by 93.4%. The flow fluctuations due to the rotating effects are minor in the Diamond TPMS architecture, considerably reducing the differences in heat transfer between the leading and trailing walls. The differences in the wetted-area averaged Nusselt number of the baseline and Diamond TPMS models within the studied rotation numbers are 8.5–14.4% and about 8.5%, respectively. Moreover, the Diamond TPMS structure reduces the differences in heat transfer between the root and tip regions at the outlet by up to 80% compared to the pin fins. This improvement helps protect the trailing edge from thermal failure, thereby potentially prolonging the gas turbine blade's lifetime.

Controlling TPMS lattice deformation for enhanced convective heat transfer: A comparative study of Diamond and Gyroid structures

This study investigates the enhancement of convective heat transfer in Triply Periodic Minimal Surfaces (TPMS), focusing on Gyroid and Diamond lattice structures. An innovative lattice structure control method, employing a Deform-Control parameter (β), is proposed to modulate lattice deformation within their mathematical frameworks. Numerical simulations validated by experimental measurements were conducted to analyze the impact of varying β values from 0 to 0.75 on the thermo-hydraulic performance of both lattice types at flow rates ranging from 0.4 m3/h to 2 m3/h. The results indicate significant improvements in heat transfer efficiency with increasing β. For Gyroid structures, increasing β from 0.1 to 0.75 led to a 3.8% to 32.7% rise in convective heat transfer coefficients and a 3.2% to 23.7% increase in Nusselt numbers. Diamond structures also demonstrated enhancements, with coefficients and Nusselt numbers climbing by 2.9% to 10.4% and 3% to 7%, respectively. Notably, both Gyroid and Diamond structures showed increase in flow resistance at higher β values, highlighting a critical balance between heat transfer efficiency and fluid flow considerations. This research presents a promising control method for optimizing heat transfer in TPMS structures, offering opportunities for more efficient and effective heat dissipation solutions.

Energy absorption of PLA-based metamaterials manufactured by material extrusion: dynamic loads and shape recovery

The objective of the study is to evaluate the performance of solid cellular structures in Polylactic Acid (PLA) by extrusion of material. The structures studied are Strut-Based, Triply Periodic Minimal Surfaces (TPMS) and Spinoidal. Impact tests allowed the identification of three categories of energy absorption (low, medium, high). The structures with lower deformation were subsequently subjected to cyclic impact tests, while the others were discarded from the analysis. Once the structures were deformed, they were immersed in a thermostat bath at 70 ºC, a temperature higher than the glass transition of PLA, necessary for the recovery of shape. TPMS structures display the best performance for high and medium impact energies, thanks to the presence of few internal defects. Spinoidal structures perform well at low impact energies but are less suitable for cyclic testing due to their geometric characteristics. Despite featuring the same density of TPMS structures, the strut based ones are not suitable for cyclic testing due to poor mechanical strength. The experimental findings are very promising as the best performing structures can be suitable for the fabrication of products with an increased life cycle, especially in the ever growing and flourishing market of technical items for impacts protection.

3D Printed Porous Zirconia Biomaterials based on Triply Periodic Minimal Surfaces Promote Osseointegration In Vitro by Regulating Osteoimmunomodulation and Osteo/Angiogenesis.

The triply periodic minimal surface (TPMS) is a highly useful structure for bone tissue engineering owing to its nearly nonexistent average surface curvature, high surface area-to-volume ratio, and exceptional mechanical energy absorption properties. However, limited literature is available regarding bionic zirconia implants using the TPMS structure for bone regeneration. Herein, we employed the digital light processing (DLP) technology to fabricate four types of zirconia-based TPMS structures: P-cell, S14, IWP, and Gyroid. For cell proliferation, the four porous TPMS structures outperformed the solid zirconia group (P-cell > S14 > Gyroid > IWP > ZrO2). In vitro assessments on the biological responses and osteogenic properties of the distinct porous surfaces identified the IWP and Gyroid structures as promising candidates for future clinical applications of porous zirconia implants because of their superior osteogenic capabilities (IWP > Gyroid > S14 > P-cell > ZrO2) and mechanical properties (ZrO2 > IWP > Gyroid > S14 > P-cell). Furthermore, the physical properties of the IWP/Gyroid surface had more substantial effects on bone immune regulation by reducing macrophage M1 phenotype polarization while increasing M2 phenotype polarization compared with the solid zirconia surface. Additionally, the IWP and Gyroid groups exhibited enhanced immune osteogenesis and angiogenesis abilities. Collectively, these findings highlight the substantial impact of topology on bone/angiogenesis and immune regulation in promoting bone integration.

Version [formula omitted]- [MaSMaker: An open-source, portable software to create and integrate maze-like surfaces into arbitrary geometries]

MaSMaker 2.0 aims to contribute to the computational design and fabrication of Triply Periodic Minimal Surface (TPMS) structures. This updated version expands the capabilities of the software in three aspects: (1) the repertoire of available TPMS structures, (2) the possibility of generating graded and hybrid TPMS prisms was added as a basic exploration tool, looking for more complex applications, and (3) introduces the functionality for recommending the resolution to build the TPMS structure depending on the Additive Manufacturing (AM) process to be used. The “isovalue” request has been replaced with a “Volume Fraction” request as a design variable, employing polynomial models derived from wide-ranging characterizations. AM recommendations come from analyzing ratios that consider cell size, cell type, and AM technology limitations to propose a design resolution. MaSMaker 2.0 combines mathematical precision and fabrication feasibility, empowering designers to seamlessly create and manufacture intricate TPMS structures.

Triply Periodic Minimal Surface Structures: Design, Fabrication, 3D Printing Techniques, State‐of‐the‐Art Studies, and Prospective Thermal Applications for Efficient Energy Utilization

This review highlights the latest developments of triply periodic minimal surface (TPMS) structures with the aim of the system's energy utilization. TPMS structures have gained widespread recognition due to their significant heat transfer (e.g., enhanced surface area) and diverse mechanical properties (e.g., structural stability), making them highly valuable in numerous thermal applications. A comprehensive survey of the design approaches, software tools, commercial materials, and 3D printing techniques of TPMS‐based structures is provided. Research gaps and future perspectives for the commercialization of TMPS structures are identified. Moreover, the potential applications of TPMS‐based structures for heat transfer augmentation and thermal management are discussed. TPMS‐based structures are promising topologies for heat exchangers on account of their intrinsically outstanding specific surface area. In this context, TPMS‐based structures have received considerable attention for various applications, including heat exchangers, latent heat storage, hydrogen storage, battery cooling/thermal management, and membrane distillation. Besides, distinct potential applications of TPMS‐based structures are proposed for heat transfer intensification and thermal management of photovoltaic/thermal collectors and fuel cells. Meanwhile, new proposals for using TPMS‐based structures for different sorption‐based applications, notably adsorption cooling/desalination systems, adsorption atmospheric water harvesting, thermochemical energy storage, and desiccant air conditioning, are nominated for forward‐looking perspectives.

Deformation and Energy Absorption Performance of Functionally Graded TPMS Structures Fabricated by Selective Laser Melting

Triply periodic minimal surface (TPMS) structures have unique geometries and excellent mechanical properties, which have attracted much attention in many fields. However, the relationship between different filling forms and different directions of functionally graded TPMS structures on energy absorption has not been fully studied. In this study, a functionally graded strategy was proposed to investigate the effect of filling form and direction gradient on the energy absorption of TPMS structures. The design of functionally graded Gyroid and Diamond TPMS cellular structures with multiple forms was characterized, and the structures were fabricated using additive manufacturing technology. The effects of uniformity and different directional gradients on the deformation and energy absorption properties of the structures were studied experimentally and numerically. According to the compression test results, it was found that different filling forms of the TPMS structure behave differently in terms of yield plateau and deformation pattern, and the sheet structures can develop a better deformation pattern to enhance energy absorption capacity. Functionally graded sheet Diamond TPMS cellular structures along the compression direction exhibit a 32% reduction in initial peak force, providing more advantages in structural deformation and energy absorption. More closely, it is possible to further reduce the initial peak force, delay the densification point, and thus increase the energy absorption capacity by designing functionally graded sheet Diamond TPMS based cellular structures. The results of this study provide valuable guidance for the design of high-performance impact-protection components.

Parametric design and performance study of continuous gradient triply periodic minimal surface bone scaffold

Continuous gradient triply periodic minimal surface (TPMS) porous structure has been proven to be one of the most suitable structures for bone implants due to their excellent mechanical properties and high porosity. This study establishes a parametric modeling method for continuous gradient TPMS structures and optimizes the TPMS porous structure with a continuous gradient change in porosity. Ti-6Al-4V continuous gradient TPMS porous structures were prepared using powder bed fusion (PBF). The mechanical properties and permeability of the continuous gradient TPMS porous structure were studied. The results indicate that the porosity control parameter C for gradient continuous change follows a linear function, with the porosity increasing linearly within the specified range of values. The influence of the periodic parameter ω on the mechanical properties and permeability of different types of TPMS structures varies. The Gyroid continuous gradient structure aligns more closely with the mechanical properties and permeability of bone scaffolds. Furthermore, a TPMS continuous gradient porous structure that is more suitable for trabecular bone implants was obtained through topology optimization design. A bone implant model and object suitable for human trabecular bone were designed and printed, providing technical support for subsequent performance testing and application research of bone implants.

Isotropic cellular structure design strategies based on triply periodic minimal surfaces

Isotropy is a desired characteristic in cellular structures for load bearing and energy absorption applications that must respond uniformly under external loads in all orientations. Triply periodic minimal surface (TPMS) cellular structures are attracting much attention for such applications due to their demonstrated high performance, tailorable properties, and open cell architecture. However, TPMS structures usually display stiffness anisotropy. In this work, new design strategies are presented for isotropic TPMS-based cellular structures, revealing a large available design space in terms of relative density and relative stiffness. The first design strategy arranges TPMS-based cells in a Simple-Cubic/Face-Centred Cubic inspired pattern, resulting in reduced elastic anisotropy. Two parametric optimisation approaches involving level-set mid-surface offsetting and the functional grading of relative density are then applied in a second step to eliminate any residual elastic anisotropy. Anisotropy is characterised through finite element analysis using the Zener ratio. Four families of cells are optimised, each based on a different TPMS unit cell, and then additively manufactured using the material extrusion process with polylactic acid. Finally, experimental quasi-static compressive tests are conducted to characterise stiffness, strength, and energy absorption properties. Optimised designs are tested in three crystal orientations ([001], [101] and [111]) and manufactured in three orthogonal print orientations. The Primitive TPMS-based design is the stiffest of the four designs reaching 64.4% of the Hashin-Shtrikman upper bound of bulk modulus at 20% relative density. Experimental results validate all four optimised cell designs for elastic isotropy and indicate that all the cell designs are also isotropic in terms of crushing strength and energy absorption.

Prediction of the mechanical properties of TPMS structures based on Back propagation neural network

Triply Periodic Minimal Surface (TPMS) has the characteristics of high porosity, a highly interconnected network, and a smooth surface, making it an ideal candidate for bone tissue engineering applications. However, due to the complex relationship between multiple parameters of the TPMS structure and mechanical properties, it is a challenging task to optimize the properties of TPMS structures with different parameters. In this study, a Back-Propagation Neural Network (BPNN) was utilized to construct the relationship between TPMS parameters. Its mechanical performance and the TPMS structure were optimized using the BPNN. Results indicated that after training the correlation coefficient (R) between the BPNN prediction and the experimental results is 0.955475, it shows that our BPNN model has an adequate accuracy in describing the TPMS structures properties. Result of TPMS structure optimization shows that after optimization the yield strength of Hybridized Gyroid-Diamond Structure (HGDS) is 6.20 MPa, which is increased by 102.61% when compared with the original Hybridized Gyroid-Diamond Structure (3.06 MPa). Result of topological morphology indicates the effective bearing area of the optimized model was increased by 12.92% compared with the original model, which ascribe the increase in yield strength of the optimization model.

Prediction of Compressive Behavior of Laser-Powder-Bed Fusion-Processed TPMS Lattices by Regression Analysis

Triply periodic minimal surface (TPMS) structures offer lightweight and high-stiffness solutions to different industrial applications. However, testing of these structures to calculate their mechanical properties is expensive. Therefore, it is important to predict the mechanical properties of these structures effectively. This study focuses on the effectiveness of using regression analysis and equations based on experimental results to predict the mechanical properties of diamond, gyroid, and primitive TPMS structures with different volume fractions and build orientations. Gyroid, diamond, and primitive specimens with three different volume fractions (0.2, 0.3, and 0.4) were manufactured using a laser powder bed fusion (LPBF) additive manufacturing process using three different build orientations (45°, 60°, and 90°) in the present study. Experimental and statistical results revealed that regression analysis and related equations can be used to predict the mass, yield stress, elastic modulus, specific energy absorption, and onset of densification values of TPMS structures with an intermediate volume fraction value and specified build orientation with an error range less than 1.4%, 7.1%, 19.04%, 21.6%, and 13.4%, respectively.

Experimental evaluation of phase-field-based load-specific shape optimization of nature-inspired porous structures

Triply periodic minimal surface (TPMS) structures excel in various research fields, ranging from bone support structures to heat exchangers. By implementing measures for shape alteration, the mechanical properties of the structure can be improved under certain load conditions. While interface-based methods such as the phase-field method have established themselves as powerful simulation techniques for the analysis of microstructure evolution and morphologically complex dynamic processes, they are not yet very well known and widely used for the application of shape optimization in mechanically loaded complex structures. In this study, an experimental procedure to validate shape-optimized samples is presented and applied to validate three computationally derived optimal candidates for sheet-based TPMS structures (Diamond, Gyroid, and Primitive) proposed by applying a mathematical model for shape optimization formulated in terms of the phase-field approach combined with linear elastic continuum mechanics and subject to the constraints of volume conservation. The present experimental study aims to validate recently obtained theoretical research results predict three different TPMS structures were shape-optimized under mechanical stress, using the phase-field method. In the following, the previous theoretical study is validated experimentally. The validation procedure creates a rare intersection between shape optimization phase-field simulations and experimental samples. The measurements show that the shape-optimized structures have a higher average stiffness, which leads to a shift in the plastic deformation range and thus confirms the computationally determined shape optimization.

Design and Compression Behavior Exploration of Skeletal and Sheet Triply Periodic Minimal Surface Structures

Six triply periodic minimal surface (TPMS) structures are designed, and their static compression behavior is evaluated in this research. TPMS structures are new type of porous structures super material, which can provide better mechanical properties than the traditional lattice structures in the engineering manufacturing field can. Six TPMS structures (Skeletal Diamond, Skeletal Gyroid, Skeletal I‐graph‐wrapped package (IWP), Sheet Diamond, Sheet Gyroid, and Sheet IWP) are actively designed by parameterization, and the relationship between parameter C and the structures’ relative density is obtained using the interpolation method. Six TPMS structures with different relative densities (10%, 20%, 30%, and 40%) are prepared by selective laser melting using Ti6Al4V powder. Static compression tests are conducted to evaluate the compression performance of these six structures. The results show that at the same relative density, sheet structures have better mechanical properties than skeletal structures. A deformation analysis of the compression process reveals that skeletal structures are dominated by layered fractures and sheet structures by overall fractures. An analysis of the overall experimental results further reveals that the Sheet Diamond structure has the best mechanical properties among the six structures, and the Skeletal Gyroid structure has the best mechanical properties among the three skeletal structures.

Adsorbent beds packed in triply periodic minimal surface-derived structures and their performance in adsorption desalination/cooling systems

The present study aims at improving the performance of adsorption desalination/cooling systems (ADCs) by packing the adsorbent materials inside triply periodic minimal surface (TPMS) structures. In that respect, solid and sheet types of metallic networks-based TPMS (e.g., Gyroid and Diamond) were addressed to improve the performance of ADCs. Using CFD simulations, the TPMS structures were compared to the finned tube-packed adsorbers based on specific daily water production (SDWP) and specific cooling power (SCP). The computational model was developed and hence verified using the most relevant literature. The influence of heat transfer area, effective thermal conductivity, effective diffusivity, and tortuosity on SDWP and SCP was investigated for the TPMS-derived and finned tube structures. Those structures were also examined using variant porosity levels. The results indicated that increasing TPMS porosity resulted in lower SDWP and SCP; however, TPMS still attained an improvement in SDWP and SCP compared to finned tube adsorbers. At a porosity of 0.8, SDWP of 10.4 m3/ton was attained by the sheet network of Diamond, which was 19.4% superior to that of the finned tube structure. At a porosity of 0.2, the sheet network of Diamond attained SDWP and SCP of 20.1 m3/ton and 627.4 W/kg, respectively.

The investigation of printing parameters effect on tensile characteristics for triply periodic minimal surface designs by Taguchi

AbstractThe advent of additive manufacturing also referred to as 3D printing, has brought about substantial changes in the industrial domain, as it possesses the capability to fabricate intricate items with enhanced cost‐efficiency and productivity. Fused Filament Fabrication (FFF) is a 3D printing process that has gained significant popularity due to its versatile capabilities and cost‐effectiveness. This paper investigates the impact of the printing parameters on the tensile characteristics of Triply Periodic Minimal Surface (TPMS) manufactured using FFF 3D printing. TPMS patterns have unique geometric properties and potential applications, making them an intriguing subject of study. The behavior of three different TPMS lattices with three printing parameters is investigated. Finding the best testing settings is done with the Taguchi method, and the data is analyzed with the Analysis of Variance (ANOVA) test. TPMS pattern was found to be the most effective parameter with 83.78%. While the highest strength was obtained in Schwarz diamond, the highest energy absorption was observed in the Gyroid structure. The contributions of printing parameters to tensile strength are line thickness, printing speed, and layer height, respectively. As line width and printing speed increase, both energy absorption and strength increase. Therefore, 0.40 mm line width and 60 mm/s printing speed give optimum values. When considered for energy absorption, the optimum value is 0.20 mm layer height, while when considered for strength, 0.10 mm layer height is the optimum value. The findings emphasize the importance of optimizing printing parameters for desired mechanical characteristics in 3D printed components and highlight the potential of TPMS structures in various applications. This research contributes to the growing knowledge in additive manufacturing and provides insights into optimizing FFF 3D printing for improved mechanical performance.

Sintering study of digital light process printed zeolite by positron, thermogravimetric and x-ray techniques

This study examined the sintering of digital light process (DLP)-printed zeolite 13X with two different phyllosilicate binders—bentonite and kaolin. DLP printing offers the potential for developing a robust additively manufactured zeolite structure that can improve upon typical adsorption column configurations by employing additively manufactured triply periodic minimal surface (TPMS) structures. Zeolite 13X is a crystalline alumina silicate material with applications in pressure swing adsorption (PSA) for CO2 and N2 gas refinement and for adsorption cooling systems. The present study developed a process to fabricate zeolite parts by DLP printing where the TPMS structures were found to hold together much better than the printed discs. Thermogravimetric analysis was used to develop debinding and sintering curves and x-ray diffraction was performed to confirm the crystalline structure of the zeolite was preserved. The micropore structure and distribution were characterized with positron annihilation lifetime spectroscopy (PALS) to investigate the effects of sintering on pore size and density. From the PALS analysis, it is concluded that DLP printing produces samples with a high surface area; however, the sintering process destroys a regular nanostructure into less regular, less crystalline, and more amorphous structure pores, which is visible by more trapping and less positronium formation with sintering in the PALS parameters.

Improving adsorption hydrogen storage performance via triply periodic minimal surface structures with uniform and gradient porosities

To improve the performance of the adsorption-based hydrogen storage via metal hydrides (MHs), high thermal conductive triply periodic minimal surface (TPMS) structures were applied in the adsorbent bed. Results showed that employing the TPMS-based structures could lead to a lower average bed temperature, a higher hydrogenation fraction and a larger adsorption amount compared to the Fins-based structure. The average temperature of the MH bed increased with increasing TPMS porosities, meanwhile the hydrogenation fraction decreased. There existed an optimal porosity leading to the maximum value of the adsorption amount. For TPMS structures with gradient porosities, at a low average porosity, the adsorption amount in Configuration II was smaller than that in Configuration I; At a high average porosity, the adsorption amount in Configuration II was larger than that in Configuration I. In Configuration II, more adsorption time was needed at low average porosities and less time at high average porosities.