3D Frame Structure Research Articles

High-energy bimetallic substituted Na3V2(PO4)3 cathode for advanced sodium-ion batteries

NASICON-type cathodes have attracted great attention due to their open three-dimensional (3D) frame structure and excellent ion transport properties. Accordingly, how to improve the stability and energy density of materials is a hot topic of research. In this study, the significant effects of aluminum-zirconium bimetallic substitution on electrode kinetics and structural stability are reported. The designed Na2.9V1.8Al0.1Zr0.1(PO4)3 cathode exhibits a highly reversible capacity of 107 mAh g-1 at 1C and decent cyclic stability (75 mAh g-1 capacity after 2000 cycles at 20C). These excellent electrochemical properties can be attributed to expanding the lattice structure and activating part of V4+, which facilitates the migration of Na+ and increases the reversible capacity. The cyclic voltammetry, electrochemical impedance spectra and galvanostatic intermittent titration technique tests analyze the diffusion kinetics of sodium ions and confirm the desired sodium ion diffusion coefficients (DNa+). In situ X-ray diffraction reveals reversible structural changes during the electrochemical reaction, which confirms that the bimetallic doping strategy slows down material volume change. This work provides a new perspective for the construction of high-performance NASICON cathode materials.

3D printed cellulose nanofiber/silica nanoparticle scaffolds for daytime radiative cooling

The high degree of modularity and miniaturization of nanoelectronic devices results in a significant increase in heat flux per unit area of electronic components. This can cause a rise in temperature, especially when used outdoors under direct sunlight conditions, which can negatively impact their operational stability and service life. Traditional radiators have limited effectiveness in outdoor sunlight conditions. Additionally, conventional heat sinks are often too large and heavy for miniature electronic devices. Therefore, finding an effective solution to cool electronics under sunlight conditions remains a challenge. Herein, we present an innovative solution to fabricate 3D-printed coolers for electronic devices based on the methyltrimethoxysilane/silica/cellulose nanofibers (MSC) ink. 3D printing technology enables the fabrication of radiative coolers with complex structures and efficient cooling performance as needed. The combination of CNFs and SiO₂ nanoparticles, coupled with the porous nature of the structure, enables the 3D-printed MSC scaffold to exhibit excellent solar reflectance and high mid-infrared (MIR) emissivity, thereby facilitating superior radiative cooling capabilities. During the daytime, it can efficiently reduce the temperature of electronic devices by 6.16 °C, thereby improving their operational efficiency and service life. Furthermore, the 3D-printed MSC scaffold exhibits superior mechanical properties due to the robust 3D frame structure formed by the ink components, which provides stability for the electronic device during operation. This study presents an innovative approach to developing electronic device coolers with excellent cooling performance, which is significant in promoting the reliability and stability of electronic devices.

Three‐Dimensional Conductive Interface and Tip Structure of MnO2 Electrode Facilitate Superior Zinc Ion Batteries

Manganese dioxide has been significantly utilized in zinc ion batteries (ZIBs). However, in the rechargeable battery system, the manganese dioxide cathode suffers from poor conductivity, volume expansion, and substance dissolution, resulting in low capacity and poor stability. Herein, a 3D frame structure MnO2@CNTs cathode is proposed. In this system, the electrodeposited spherical MnO2 is anchored and interlinked via the in‐situ growth carbon nanotubes (CNTs) onto the carbon cloth. Benefiting the unique 3D frame structure, the MnO2 structure crush problem and the pathway of the electrons and ions are dramatically improved. The optimized MnO2@CNTs cathode demonstrate a high capacity of 256.35 mAh g−1 at 0.1 A g−1 and exceptional cycling stability. Furthermore, in‐situ Raman spectroscopy elucidates the energy storage mechanism of aqueous ZIBs (AZIBs). Moreover, COMSOL finite elements analysis demonstrates that the petal edge‐rich nanostructures of MnO2@CNTs generate a localized high electric field under constant current, accelerating ion/electron transfer. This work explains the rationale for CNTs to improve the properties of MnO2 cathodes, providing a new perspective for the design of high‐performance batteries.

A plastic hinge method for static pushover analysis of 3D frame structures

ABSTRACT In this paper, a nonlinear elasto-plastic analysis method under incremental external loads is presented to determine static pushover curves of 3D frame structures. Geometric nonlinearity is taken into account with stability functions, and the nonlinear behaviour of material is considered by plastic hinge hypothesis. Improved matrices and matrix operations for 3D frame elements are given, and the results obtained from a six-storey 3D frame, which is used as a benchmark example, are given comparatively with the related studies. Furthermore, in order to perform these analyses with the developed algorithms, the upgraded computer program TUNAL is used to present pushover curves of a 2-storey RC building for an assumption on torsional stiffness caused by plastic hinges. It is shown that the proposed methodology and the computer program give accurate and reliable results.

Dynamic progressive collapse response of 3D monolithic precast concrete frame structures considering slab effects

The robustness of precast concrete frame structures to withstand extreme events like explosions, impacts, fires and terrorist attacks has attracted growing attention. With the understanding of the static progressive collapse performances of 2D precast frame structures, research on the dynamic responses of 3D precast frame structures is pressing and high in demand. To evaluate the influence of floor slabs on dynamic progressive collapse responses of 3D precast concrete frame structures, an experimental program consisting of a beam-column (PC) and a beam-slab-column (PCS) specimens was first designed, followed by the analysis of the working mechanisms to resist progressive collapse. The modeling techniques for 2D PC and PCS substructures were then proposed and validated using the test results. The numerical strategy was further extended to simulate the dynamic progressive collapse responses of 3D PC- and PCS-frame structures. Results show that, under various column loss scenarios, floor slabs significantly improve progressive collapse resistances of 3D frame structures. Moreover, it reveals that the floor slabs have a remarkable effect on reducing the nodal displacements and the dynamic amplification factors.

Tetradecanoate in situ reaction prepares a stable and efficient 3D framework for fog collection

Slippery liquid-infused porous surface (SLIPS) strategy has recently attracted significant attention in the field of foggy water collection. However, the surface on which the lubricant is injected is often unstable, losing control of fog capture and droplet movement. The 3D frame structure combined with the nano-needle-like structure produces a strong oil locking ability to provide more stable Slippery liquid-infused porous surface. In this work, copper myristate flower-like clusters were directly grown on the walls of porous copper foam wires by in situ reactions, resulting in a superhydrophobic skeleton directly, and a 3D skeleton of the injected lubricant was obtained after lubricant injection. The framework also features excellent droplet capture, droplet coalescent growth, and droplet removal, as well as significant anti-ice and anti-fouling properties. This work simplifies the preparation process and it is easy to meet the reaction conditions. The prepared lubricant injected skeleton has excellent atomized collection properties (98.7% higher than the original sample) and has the potential for mass fabrication. It provides a new idea for the efficient and rapid preparation of the liquid infusion fog collection structure.

Achieving sustainable built-environment using bamboo composite frame system with cow-dung masonry infills

In today's rapidly urbanizing world, there is dire need for adopting the principles of green/ sustainable built-environment so as to mitigate the ill effects of environmental degradation and climate change. However, demand for housing is on rise in developing countries like India, where sizeable population, especially the low-income strata, still lacks decent quality structurally safe housing. Extensive use of concrete and steel in construction over more than a century has led to detrimental environmental effects such uncontrolled release of greenhouse gases/ pollutants, deforestation and erosion, leading to now visible outcomes of climate change. Bamboo, on other hand provides a sustainable alternative to concrete and steel as a building material since it absorbs the atmospheric carbon dioxide, produces more oxygen than timber producing trees and is a lightweight and renewable building material. Unlike timber, it matures in four to five years and being grass family, is replenishable in nature. However, from structural point of view, the main drawback of bamboo culm is its large slenderness ratio, which renders it weak in resisting bending and compressive loads. This paper presents an alternate structural system utilizing fibre reinforced bamboo composite (FRBC) to overcome the structural deficiency of a single shoot bamboo and build a prototype structure after detailed laboratory evaluation and structural analysis. Structural elements made from FRBC are utilized for fabricating a prototype 3D frame structure, measuring about 24 m2 in plan, representing a modular unit amenable to horizontal and vertical expansion. Eco-friendly materials like cow-dung based bricks and mortar, which offer net zero additional carbon dioxide emissions and circumvent reliance on cement and river sand, have been utilized as masonry infills after structural evaluation. The built structure provides a proof-of-concept demonstration of the feasibility of using bamboo and cow-dung, sustainable building materials, for achieving a structurally safe built-environment. The technology is especially suitable for countries like India which are endowed with tropical climatic conditions. By adopting such environmentally friendly alternatives, the construction industry can create a healthier environment while addressing housing and infrastructure needs in sustainable manner.

Corotational force-based beam finite element with rigid joint offsets for 3D framed structures

In numerical analysis of frame structures, modeling of the connection between structural members often requires the introduction of rigid end offsets to correctly describe the stiffness of the joints. This is typical of beam-to-column connections in civil constructions but is also common in lattice materials, where the element overlapping at the joints locally increases the stiffness of the nodes. However, when nonlinear geometric effects are included, correct simulation of such phenomena is challenging.This paper presents a geometrically nonlinear three-dimensional force-based beam finite element that efficiently accounts for the effects of rigid joint offsets. The model imposes the element equilibrium in the local reference system referring to the element deformed configuration, considering the von Kármán nonlinear terms, and exploits a corotational formulation to account for rigid large displacements and rotations of the beam. Two alternative approaches are used to introduce the rigid offsets. The first derives from an existing proposal where kinematic and static nonlinear operators are adopted to describe the behavior of the rigid portions at the element ends. The second is a novel approach, easier to implement and use, that involves modifying the integration, along the element axis, of the cross-section strains and flexibility. This can be easily defined for beam models under linear geometry assumption but requires particular attention for the analysis of frame structures under large displacements and strains. Both approaches are validated through numerical examples, including comparison with other numerical methods and experimental results available in the literature.

A Small-Deformation Rate-Independent Continuous-Flow Model for Elasto-Plastic Frames Allowing Rapid Fatigue Predictions in Metallic Structures

Fatigue analysis in metallic frame structures can be challenging due to associated computational costs; if localized plasticity is involved, then the approach of three-dimensional (3D) continuum plasticity models for direct computation of stresses will be infeasible for the analysis of cyclic loading that would need to be modeled in medium- to high-cycle fatigue and vibratory fatigue applications. This difficulty is particularly accentuated in architected structures, for which high-resolution 3D finite element analysis (FEA) would be prohibitively expensive. In this work, we propose an alternative approach based on the use of novel elasto-plastic frame model with continuous flow (i.e. no sharp yield function) for modeling 3D frame and lattice structures. Rather than splitting the strains (as is done in classical plasticity) we split the deformation measures, extension, curvature and twist, into elastic and plastic components and postulate a rate type evolution rule for the plastic variables in terms of the stress resultants (axial force, bending moment, and torque). The combination of structural models together with the use of elasto-plastic operator split to solve the resulting boundary value problem allows for much faster determination of localized plasticity than continuum models can provide. The use of a continuous transition from elastic to rate-independent plasticity (as opposed to an abrupt change with classical plasticity models) allows us to capture localized microplasticity and determine resulting fatigue progression using a cycle-count-free, plastic work-based approach, formulated in terms of the curvatures and resultants. We demonstrate that (a) the model is able able to reproduce the response of 3D FEA with very few elements and (b) the model has the ability to rapidly predict the fatigue life under variable amplitude combined loading with relatively few frame elements.

Novel closed-form expressions for potential energy estimation in 3D frame structures

Novel closed-form expressions for potential energy estimation in 3D frame structures

Experimental assessment of an asymmetric steel–concrete frame under a column loss scenario

Several noteworthy accidents clearly pointed out the risk of disproportioned collapse of framed structures. Design codes recently recognized it by adding a new requirement: the structural robustness. Among the different approaches to check robustness, the most popular is associated with the column loss scenario: the analysis should verify that, in case of a column loss, an alternative load path does exist, limiting the portion of structure affected by collapse. Consequently, numerous experimental and numerical studies of 2D and 3D structures were carried out in recent years to identify the mechanism of load transfer from the damaged to the undamaged part of the structure. This knowledge becomes an essential and fundamental key for assuring adequate resistance against progressive collapse by the development of catenary action in the beams and membrane action in the floor slab. Studies of reinforced concrete systems and of bare steel sub-assemblies are numerous. More recent is the focus on the response of steel–concrete composite structures subjected to accidental events. Furthermore, most of these studies focused on the characterization of 2D sub-assemblies or 3D in-scale framed structures. This paper presents an experimental assessment of the structural response of a 3D full-scale steel and concrete composite frame under the column loss scenario. The results are finally compared with the response of a frame with the same overall geometry but different columns’ layout, tested by the Authors within the same research programme.

Deep learning aided inverse design of the buckling-guided assembly for 3D frame structures

Buckling-guided assembly of three-dimensional (3D) mesostructures from pre-defined 2D precursor patterns has arisen increasing attention, owing to the compelling advantages in developing 3D electronic devices and systems with novel functionalities and/or capabilities. Establishments of rational inverse design methods that allow accurate mapping of the target 3D configuration onto the initial 2D precursor pattern are crucial to the widespread application of buckling-guided assembly methods. While a few methods (e.g., those based on theoretical models and generic algorithms) have been reported for the inverse design of 3D frame structures with interconnected ribbons, limitations still exist in their applicable 3D geometries or computational efficiency. In this work, we report an effective inverse design method based on the point-cloud deep learning neural network (DLNN) model for the buckling-guided assembly of 3D frame structures. A structure-based database in the point-cloud form is established based on massive finite element analyses (FEA) of postbuckling deformations for diverse 2D precursor patterns with different numbers of intersections. The well-trained deep learning models assisted by transfer learning strategy utilizing datasets in the constructed database are verified to establish the end-to-end implicit mapping between the 3D frame structure and corresponding 2D precursor pattern. Computational and experimental demonstrations over a bunch of complexly shaped structures, including those resembling 3D shapes of real-world objects, illustrate the high efficiency and accuracy of the proposed deep learning aided inverse design method. In comparison to previously reported methods based on genetic algorithms, the proposed inverse design method can save much more computational efforts, and does not require the initial guess of the 2D precursor pattern. Furthermore, the proposed inverse design method offers an excellent extensibility, as the size and diversity of the structure-based database can be continuously expanded in a sustainable manner, with the future development of buckling-guided assembly methods.

Hg3(SeO3)2(SO4): A UV Nonlinear Optical Mercury Selenite Sulfate Constructed by Neat [Hg6O8(SeO3)4]∞ Layers and SO4 Tetrahedra.

A novel mercury selenite sulfate named Hg3(SeO3)2(SO4) has been successfully synthesized under a mild hydrothermal method. Hg3(SeO3)2(SO4) crystallizes in a monoclinic space group P21 and features a unique three-dimensional (3D) frame structure formed by [Hg6O8(SeO3)4]∞ layers and SO4 tetrahedra, which enables it to exhibit a comprehensive performance of a moderate second-harmonic generation (SHG) response of approximately 1.3 times that of baseline KH2PO4 (KDP), a moderate birefringence (0.118@546 nm), and a wide band gap (4.70 eV), which indicates that it has potential for application as an ultraviolet (UV) nonlinear optical material. Detailed theoretical calculations show that the Hg2+-based polyhedra with large polarizability and deformability and the SeO3 groups with stereochemically active lone pair (SCALP) electrons are the main contributors to moderate optical properties.

Shape optimization of 2D beam-structures to obtain the uniform strength

This paper provides a new method to design the optimal shape of 2D frame structures even (or especially) if not statically determined. The optimization here addressed involves obtaining the uniform strength of the whole structure, but the proposed procedure can be followed for other optimization goals. Two types of beam cross-sections are studied, in which the solution in terms of balance, kinematic and beam-shape is found analytically and involves six unknowns for every beam element. For frame structures, some internal and external constraint conditions must be satisfied; using the analytical solution within the boundary conditions, the optimization problem boils down to finding the roots of a non-linear system. This way allows to work inside the optimization workspace, avoiding the use for each iteration of other solvers (e.g. F.E. software) and obtaining the solution with a high-computation speed. Two tests are shown, which result in a uniform-strength behaviour of the maximal stress at every cross section, and a lightness gain higher than 70% by respect to the reference initial structure. This technique can be extended to other types of cross-sections or 3D frame structures.

Large displacement analysis of laminated beam-type structures

The paper presents a finite element formulation for analysis of 3D framed structures with thin-walled laminated composite cross-sections, using a co-rotational approach. The formulation considers the effects of large displacements on the response of space frames subjected to conservative and static external loads. Classical lamination theory for thin fiber-reinforced laminates has been employed. Stability analysis is performed in load deflection manner using co-rotational formulation. The shear strain of the middle surface is assumed to be zero, and the cross-section is not distorted in its own plane. In order to illustrate the application of the proposed formulation, several numerical examples are presented.

Rational construction of Prussian blue analogue with inverted pyramid morphology as ultrastable cathode material for lithium-ion battery

Prussian blue analogue material is regarded as an ideal cathode candidate for Li-ion batteries due to its open 3D frame structure and various transition metals with different valence states. However, poor electronic conductivity and structural collapse severely limit its application in the electrochemical field. In this work, Na1.13Fe[Fe(CN)]6·3.22H2O electrode materials with stepwise hollow inverted pyramid morphology are prepared by simple hydrothermal method. The inverted pyramid Na1.13Fe[Fe(CN)]6·3.22H2O maintains the stability of the crystal structure and slows down the volume expansion during the Li + insertion-extraction process. Benefiting from the unique structure and composition, the discharge specific capacities of the optimal Na1.13Fe[Fe(CN)]6·3.22H2O electrode (FeHCF-2) are 153.7, 126.28, 119.4 and 113.4, 107.61, 102.52 and 92.46 mAh·g−1 at 0.1, 0.3, 0.5, 1, 2, 5 and 10 C, respectively. The first discharge capacity of FeHCF-2 electrode at 1 C is 111.88 mAh·g−1, and the discharge capacity of FeHCF-2 electrode is 115.04 mAh·g−1 after 1000 cycles, indicating that FeHCF-2 electrode has ultrastable cycle stability. Therefore, designing the hollow inverted pyramid morphology can be regarded as an available way to enhance the electrochemical activity of Na1.13Fe[Fe(CN)]6·3.22H2O for advanced lithium-ion batteries, and effective design strategies can be used for the modification of other cathode materials for Li-ion batteries.

Investigation on the progressive collapse resistance of three-dimensional concrete frame structures reinforced by steel-FRP composite bar

Compared with conventional steel bars, steel-FRP (fiber reinforced polymer) composite bars (SFCBs) have distinctive post-yield stiffness, and the high efficiency of SFCBs in enhancing the progressive collapse resistance of concrete frames has been confirmed by recent quasi-static experimental studies on SFCB beam–column subassemblages. However, the realistic progressive collapse of structures is a dynamic process, and the three-dimensional (3D) effects are essentially important for determining the collapse response. In this study, numerical models are built to explore the progressive collapse behavior of 3D frame structures reinforced by SFCBs. The static and dynamic capacities of five SFCB frames and one reinforced concrete (RC) frame are compared under different column–removal cases. Results show that by virtue of the post-yield stiffness, the static load factors of SFCB frames are much larger than those of RC frames at the same deformation, proving that SFCB frames have better robustness against collapse failure than RC frames. After the dynamic removal of columns, all RC frames are subjected to progressive collapse failure, while SFCB frames can successfully complete the dynamic load redistributions and quickly reach a steady state. Further, the dynamic increase factor (DIF) of SFCB frames is proposed based on the ratio of maximum dynamic flexural responses to static flexural responses of beam joint sections under the same gravity loads (1.2 times dead load plus 0.5 times live load), and the conservative DIFs of 1.55 and 1.3 are recommended for a corner column–removal case and the other single column–removal cases, respectively. Finally, parametric analyses are conducted to reveal the effect of beam longitudinal reinforcement ratio, beam span-to-depth ratio, and dynamic duration for the column removal on the progressive collapse resistance of SFCB frames. The results lay a foundation for the progressive collapse design of 3D SFCB frame structures.

Novel amine-functionalized zinc-based metal-organic framework for low-temperature chemiresistive hydrogen sensing

Low-temperature operating chemiresistive gas sensors are attractive for a variety of real-time gas monitoring applications, with benefits such as low power consumption, profitability, and miniaturization of devices. In this regard, we developed a low-temperature operating H2 gas sensor using solvothermal-processed novel amine-functionalized zinc-based metal-organic framework (Zn-BDC-NH2) as a detection material. The Zn-BDC-NH2 structure is consists of the Zn4O secondary building units and 2–aminoterephthalate acidic linker that form the 3D frame structure. Prior to sensing studies, various techniques were employed to confirm -NH2 functionalization and to characterize structure, surface morphology, thermal stability, surface area, and surface chemistry of synthesized Zn-BDC-NH2 materials. Benefitting from the simple synthesis process and larger surface area (880 m2g-1) with adequate porosity (~13 Å), Zn-BDC-NH2 has proven to be an excellent chemiresistive sensor for the effective sensing of low concentrations of H2 at 50 °C. Moreover, the sensor shown significant sensitivity to the detection of lower H2 concentrations of 1–10 ppm, a response value of 2.93–10 ppm H2, and complete recovery characteristics at 50 °C. We discussed the mechanisms for attaining the excellent H2 sensing. The utilized room temperature solvothermal approach opens up a perspective for synthesizing Zn-BDC-NH2 material with suitable functionalities and their use in low temperature H2 sensors.

A reduced order model for nonlinear time history seismic analyzes of elasto‐plastic 3D frame structures

AbstractA reduced order model for the nonlinear dynamic seismic analysis of elasto‐plastic 3D frame structures is presented. It is based on an approximated solution space for the displacement field that is assumed as the sum of two subspaces. The first subspace is generated by the relevant linear elastic modes of the generalized stiffness/mass linear eigenvalue problem in terms of participation factor. The second one is defined by collapse mechanisms associated to appropriate static load distributions. The time history analyzes are carried out within the reduced solution space, while the internal forces are evaluated on the full model to guarantee an accurate description of the constitutive laws. The proposed reduction method was tested for different structural geometries varying frequency content, direction and amplitude of the ground motion. Numerical results show accuracy and robustness also employing a few tens of modes, including elastic modes and plastic collapse mechanisms. In particular, the need for plastic modes in capturing the structural dynamics in case of seismic actions leading to significant plastic excursions is emphasized. This highlights the limits of simplified approaches based on the hypothesis of shape conservation in nonlinear problems, regardless of the building regularity.

Study on 3D multi-performance composite films of Fe3O4 decorated CNTs/graphene oxide

In this work, three-dimensional (3D) Fe3O4 decorated CNTs/graphene oxide (Fe3O4-CNTs/GO) composite film was used to enhance glass fiber reinforced polymer (GFRP) resulting in three excellent performances of interlaminar toughening, resistance to temperature changes, and electromagnetic interference (EMI) shielding were all achieved. The end notch bending (ENF) test results showed that Fe3O4-CNTs/GO film enhanced GFRP was 60.51% and 79.64% higher than the baseline (GFRP without reinforcement film) after RT or temperature cycle treatment, while the GFRP of pure CNTs film was 21.79% and 26.34% higher than the baseline, respectively. The change in interlaminar toughness of Fe3O4-CNTs/GO samples by temperature cycle was also lower than that of the other two samples (Fe3O4-CNTs/GO film: 4.15%, pure CNTs film:11.15%, baseline: 14.35%). The average EMI shielding effectiveness of Fe3O4-CNTs/GO films with a thickness of only 0.052 mm was 25 dB, about 500% higher than the 5 dB of the control group (ordinary CNTs/Fe3O4/GO films, thickness 0.047 mm). Scanning electron microscopy (SEM) further confirmed the existence of the 3D frame structure and interlamellar strengthening interface of Fe3O4-CNTs/GO films.