Structure Design Research Articles

Comprehensive Insights on MXene-Based TENGs: from Structures, Functions to Applications.

The rapid advancement of triboelectric nanogenerators (TENGs) has introduced a transformative approach to energy harvesting and self-powered sensing in recent years. Nonetheless, the untapped potential of TENGs in practical scenarios necessitates multiple strategies like material selections and structure designs to enhance their output performance. Given the various superior properties, MXenes, a kind of novel 2D materials, have demonstrated great promise in enhancing TENG functionality. Here, this review comprehensively delineates the advantages of incorporating MXenes into TENGs, majoring in six pivotal aspects. First, an overview of TENGs is provided, stating their theoretical foundations, working modes, material considerations, and prevailing challenges. Additionally, the structural characteristics, fabrication methodologies, and family of MXenes, charting their developmental trajectory are highlighted. The selection of MXenes as various functional layers (negative and positive triboelectric layer, electrode layer) while designing TENGs is briefed. Furthermore, the distinctive advantages of MXene-based TENGs and their applications are emphasized. Last, the existing challenges are highlighted, and the future developing directions of MXene-based TENGs are forecasted.

Optimization design of composite cap-shape pillar structure based on gaussian process of combined kernel function

Abstract To quickly realize the optimal design of the cap-shaped structure, an optimization design method of composite cap-shaped pillar structure based on combined kernel function Gaussian process was proposed. First, the shortcomings of two kernel functions representing different linear characteristics of data in model construction were analyzed, on which a new combined kernel function was constructed. Based on the finite element numerical simulation results, a database with the web thickness, web height, fiber volume, and ultimate bearing capacity of the cap-shaped structure was constructed. Then, a Gaussian process model based on the combined kernel function was established and the model parameters were trained by the maximum likelihood method. Finally, taking the ultimate bearing capacity per unit volume as the optimization objective, the artificial fish swarm algorithm was used to quickly obtain the structure design parameters under the optimal objective function, and the simulation results were compared with the initial design parameters. The results showed that the method proposed in this paper can optimize the structure performance, improve the design efficiency, and meet the engineering design requirements.

Structure design and mechanism research of combined cyclone plate separator based on particle separation

Although there has been much research on the gas–solid separation equipment of cyclone plate, there is still a lot of research space for miniaturization, low resistance, and easy maintenance. In this paper, parallel gas–solid separation equipment is designed based on computational fluid dynamics and experimental verification methods to address the practical problems faced by the fresh air system of the enterprise plant. The internal flow field of the separator is studied by numerical simulation, and the structural parameters of the separator are optimized according to the performance indicators provided by the enterprise. The optimal structure that meets the performance requirements and has the best effect is determined. Subsequently, the actual performance of the optimal structure was verified by wind tunnel experiments, and the deviation between the experimental results and the numerical simulation results was compared. The results show that increasing the number of blades, adjusting the blade angle, and increasing the height of the outer cylinder are beneficial in improving the internal flow field of the separator. Among them, the blade angle significantly affects the tangential velocity and axial velocity of the separator. When these three parameters are increased, the filtration efficiency increases first and then decreases. Finally, when the number of blades is 8, the blade angle is 50°, and the height of the outer cylinder is 0.63 m, the separation efficiency is the highest, and the pressure drop is the lowest. This structure satisfies all performance indicators. The experimental results show that the minimum filtration efficiency is 92.4%, and the maximum pressure drop does not exceed 500 Pa. Compared with the numerical simulation results, the experimental value is 0.29% lower, which shows that the structure has good separation performance and has a significant reference value for the fresh air system of the industrial workshop.

High-Volumetric-Energy-Density Cathode Material from Single-Sized Precursor via Precise Additive Control

To overcome the energy density limitations of current layered cathode materials, high-nickel cathode materials with a bimodal distribution composed of ∼ 15um-sized secondary particles and micron-sized single crystals are synthesized from a single-sized high-nickel precursor by incorporating the grain-growth promoting/inhibiting additive. Synthesized cathode material effectively reduces the pores within the electrode and shows an excellent electrode density of > 3.9 g/cm3, exceeding ∼ 80 % of the theoretical density. In addition, due to efficient contact between large secondary particles and small single crystals, bimodal particles with additives show higher electrical conductivity compared to additive-free monomodal secondary particles, and a capacity of ∼ 220 mAh/g is achieved even at a high loading level of ∼ 30 mg/cm2 and 96 % active-material fraction. Based on remarkable electrode density and high capacity, it is possible to realize a volumetric energy density of more than 700 mAh/cm3. To the best of our knowledge, this is the highest energy density result for electrodes made from layered cathode materials. Moreover, through the synergistic effect of morphology control by selective additives and surface coating, the synthesized bimodal cathode simultaneously exhibits excellent capacity as well as improved cycle-life performance compared to a bare cathode without additives. The enhanced electrochemical performance is attributed to increased connectivity between individual cathode particles, decreased bulk/surface resistance, and reduced intergranular cracks after cycling through structure design by additives, which is confirmed through various electrochemical analyses and electrode observations.

Bulk/Interfacial Structure Design of Li-Rich Mn-Based Cathodes for All-Solid-State Lithium Batteries.

Li-rich Mn-based cathode materials (LRMO) are promising for enhancing energy density of all-solid-state batteries (ASSBs). Nonetheless, the development of efficient Li+/e- pathways is hindered by the poor electrical conductivity of LRMO cathodes and their incompatible interfaces with solid electrolytes (SEs). Herein, we propose a strategy of in-situ bulk/interfacial structure design to construct fast and stable Li+/e- pathways by introducing Li2WO4, which reduces the energy barrier for Li+ migration and enhances the stability of the surface oxygen structure. The reversibility of oxygen redox was improved, and the voltage decay of the LRMO cathode was addressed significantly. As a result, the bulk structure of the LRMO cathodes and the high-voltage solid-solid interfacial stability are improved. Therefore, the ASSBs achieve a high areal capacity (∼3.15 mAh/cm2) and outstanding cycle stability of ≥1200 cycles with 84.1% capacity retention at 1 C at 25 °C. This study offers new insights into LRMO cathode design strategies for ASSBs, focusing on ultrastable high-voltage interfaces and high-loading composite electrodes.

Structure design and analysis of circle wheel angle fine-tuning mechanism

Structure design and analysis of circle wheel angle fine-tuning mechanism

Intelligent design of multi-layered variable stiffness composite structure based on transfer learning

Variable stiffness composite structures offer more flexible design space than thin-walled metal structures and have greater potential for vibration-resistant design. When faced with multiple new types of design problems, the complex modelling and analysis procedures frequently prove to be both time-consuming and costly in terms of optimization. In this study, an innovative multi-layered variable stiffness (MVS) composite structure with high design flexibility is proposed, with images representation for curvilinearly stiffened paths, non-uniform layouts, and fiber and layup angles. Moreover, an intelligent optimization method based on transfer learning is proposed for addressing a variety of factors affecting dynamic design, including boundary types, structural features, and dynamic responses. The objective of the transfer learning model is to facilitate the inheritance and sharing of variable stiffness features, thereby enabling the efficient design of new problems with limited datasets. The validation of different examples shows that the transfer learning can effectively acquire the structural features from the existing source domain datasets, thereby significantly reducing the data for some new target domains by approximately 50%. In comparison to the initial constant stiffness (CS) structures, the different optimized configurations indicate that the MVS composite structures are capable of effectively enhancing the dynamic responses by 10%∼146% for natural frequency and dynamic compliance. Furthermore, the MVS optimized configuration displays superior dynamic responses in some problems, when compared to the CS optimized configuration.

Design and technological analysis of the multi-position progressive die for the clamp

Abstract The technological process of the clamp part is analyzed, the design of the stamping and bending process for the clamp is introduced, including determination of the operation sequence and operation position parts dimensions. The process is used side blade settles to distance, pilot pin was used in exact positioning, the blanking and bending of the part were carried out continuously. The design of the general structure, layout of the progressive and forming characteristics die for the clamp is introduced in detail, the method for designing and calculating the key parts.

Simulation analysis and hydrodynamic performance optimization of small MHD thruster based on improved I-bridge structure

Abstract Magnetic hydrodynamic drive (MHD) generates thrust by the coupling interaction of three fields: flow field-electric field-magnetic field. Because this propulsion method has no propeller or mechanical structure, it has the advantages of quiet, simple structure, easy operation, flexible layout, and difficult to detect. This is the current research hot spot. In order to meet the needs of miniaturized silent propulsion, this paper selects a linear internal magnetic thruster for research and analysis and improves the design of an I-shaped magnetic bridge structure. Firstly, the thrust and efficiency of the thruster under ideal conditions are calculated, and the thruster model is established. The conclusion is that the I-shaped magnetic bridge can increase the magnetic field intensity of the channel and significantly improve the MHD propulsion efficiency. At the same time, it is found that MHD thruster can reduce noise during operation, but the current required for propulsion is large, and seawater electrolysis will occur, which has a certain impact on the environment. Finally, the problems of small direct drive MHD propulsion are analyzed, and the future development direction of MHD propulsion is prospected.

Nanoconfinement of MgO in nitrogen pre-doped biochar for enhanced phosphate adsorption: Performance and mechanism

Advanced metal-doped biochar with superior phosphate (P) adsorption capacity plays a crucial role in combating eutrophication, depending on the rational design of the biochar structure for uniform and nanoscale dispersion of metal oxides. Herein, the nanoconfinement of magnesium oxide (MgO) was successfully attained in nitrogen pre-doped biochar (Mg/N-BC). The well-dispersed MgO was confined within nanoscale structure of Mg/N-BC, delivering P adsorption capacity of 108.41 mg g−1 and adsorption rate of 18.01 mg g-1h−1. More importantly, its adsorption performance at equilibrium 0.5 mg P/L was 17.70 times higher. Results suggested the decrease in pore size was positively correlated with the increase of N, confirming the role of N pre-doping in structure shaping and MgO confinement. The enhanced P adsorption was attributed to the well-dispersed MgO nanoparticles within the biochar. This study introduced a facile synthesis approach for biochar-incorporated nanoscale MgO, offering a new strategy for enhanced P removal.

Terahertz Beam Shaping Using Space-Time Phase-only Coded Metasurfaces

Digital metasurfaces as space-coded surfaces composed of a set of sub-wavelength meta-atoms enable extraordinary capabilities to manipulate electromagnetic waves. Recently, amplitude-phase-joint-coding metasurfaces have been proposed to achieve enhanced beam shaping. However, design of a unit cell structure with a full manipulation of amplitude and phase of the reflected beam is challenging and this kind of unit cell structures are complicated. This paper proposes a space-time phase-only metasurface based on simple graphene-based unit cell that is digitally coded and arranged with a specific time sequence, allowing the effective simultaneous manipulation of both phase and amplitude. In this way, it is demonstrated that the terahertz beam can be shaped using the proposed terahertz metasurface.

Revolutionizing Intervertebral Disc Regeneration: Advances and Future Directions in Three-Dimensional Bioprinting of Hydrogel Scaffolds.

Hydrogels are multifunctional platforms. Through reasonable structure and function design, they use material engineering to adjust their physical and chemical properties, such as pore size, microstructure, degradability, stimulus-response characteristics, etc. and have a variety of biomedical applications. Hydrogel three-dimensional (3D) printing has emerged as a promising technique for the precise deposition of cell-laden biomaterials, enabling the fabrication of intricate 3D structures such as artificial vertebrae and intervertebral discs (IVDs). Despite being in the early stages, 3D printing techniques have shown great potential in the field of regenerative medicine for the fabrication of various transplantable tissues within the human body. Currently, the utilization of engineered hydrogels as carriers or scaffolds for treating intervertebral disc degeneration (IVDD) presents numerous challenges. However, it remains an indispensable multifunctional manufacturing technology that is imperative in addressing the escalating issue of IVDD. Moreover, it holds the potential to serve as a micron-scale platform for a diverse range of applications. This review primarily concentrates on emerging treatment strategies for IVDD, providing an in-depth analysis of their merits and drawbacks, as well as the challenges that need to be addressed. Furthermore, it extensively explores the biological properties of hydrogels and various nanoscale biomaterial inks, compares different prevalent manufacturing processes utilized in 3D printing, and thoroughly examines the potential clinical applications and prospects of integrating 3D printing technology with hydrogels.

Failure Behavior and Mechanism of Vat Photopolymerization Additively Manufactured Al2O3 Ceramic Lattice Structures

Vat photopolymerization additive manufacturing produces lightweight load-bearing ceramic lattice structures that have flexibility, time-efficiency, and high precision, compared to conventional technology. However, understanding the compression behavior and failure mechanism of such structures under loading remains a challenge. In this study, considering the correlation between the strut angle and bearing capacity, body-centered tetragonal (BCT) lattice structures with varying angles are designed based on a body-centered cubic (BCC) structure. BCT Al2O3 ceramic lattice structures with varying angles are fabricated by vat photopolymerization. The mechanical properties, deformation process, and failure mechanism of the Al2O3 ceramic lattice structures are characterized through a combination of ex- and in-situ X-ray computed tomography (X-CT) compression testing and analyzed using a finite element method (FEM) at macro- and micro-levels. The results demonstrate that as the angle increases, the stress concentration gradually expands from the node to the strut, resulting in an increased load-bearing capacity. Additionally, the failure mode of the Al2O3 ceramic lattice structures is identified as diagonal slip shear failure. These findings provide a greater understanding of ceramic lattice structure failures and design optimization approaches.

Jellyfish-Inspired Polyurea Ionogel with Mechanical Robustness, Self-Healing, and Fluorescence Enabled by Hyperbranched Cluster Aggregates.

Ionogels are promising for soft iontronics, with their network structure playing a pivotal role in determining their performance and potential applications. However, simultaneously achieving mechanical toughness, low hysteresis, self-healing, and fluorescence using existing network structures is challenging. Drawing inspiration from jellyfish, we propose a novel hierarchical crosslinking network structure design for in situ formation of hyperbranched cluster aggregates (HCA) to fabricate polyurea ionogels to overcome these challenges. Leveraging the disparate reactivity of isocyanate groups, we induce the in situ formation of HCA through competing reactions, enhancing toughness and imparting the clustering-triggered emission of ionogel. This synergy between supramolecular interactions in the network and plasticizing effect in ionic liquid leads to reduced hysteresis of the ionogel. Furthermore, the incorporation of NCO-terminated prepolymer with dynamic oxime-urethane bonds (NPU) enables self-healing and enhances stretchability. Our investigations highlight the significant influence of HCA on ionogel performance, showcasing mechanical robustness including high strength (3.5 MPa), exceptional toughness (5.5 MJ m-3), resistance to puncture, and low hysteresis, self-healing, as well as fluorescence, surpassing conventional dynamic crosslinking approaches. This network design strategy is versatile and can meet the various demands of flexible electronics applications.

Sound velocity measurement based on laser-induced micro-flyers

The measurement of high-pressure sound velocity in solid materials is crucial for developing constitutive equations and equations of state for materials in extreme stress–strain rate conditions. In this study, we propose a novel method for high-pressure sound velocity measurement using laser-induced micro-flyer technology. By optimizing laser driving conditions and target structure design, we measure high-pressure sound velocity using the “reverse-impact geometry” approach. The well-established Photon Doppler Velocimetry system allows for high-precision, single-shot measurements of both flyer velocity and particle velocity histories. A systematic error analysis shows that the longitudinal sound velocity of aluminum obtained in this experiment is consistent with data from traditional devices, such as gas guns, within the error margin. Finally, we analyze the potential application value of this method in laser technology as well as high-pressure dynamic responses of materials, and conclude the current shortcomings and possible improvements of this method.

Fabrication of core-shell Fe4N@C with sea-island structure by one-step nitriding method as efficient electromagnetic wave composite absorber

Porous structure design and magnetic-dielectric composite are effective ways to develop electromagnetic wave (EMW) absorbing materials with light-weight, thin-thickness, large effective absorption bandwidth (EAB), and strong reflection loss (RL). This article presents a simple one-step nitridation method for synthesizing Fe4N@C compounds with sea-island like and core-shell structures. The optimal RL value of Fe4N@C is up to -60.01dB, and the EAB (frequency range for RL< -10 dB) is 5GHz (11.1-16.1GHz) with a thickness of 1.9mm. The EAB reaches 5.5GHz (12.5-18GHz) when the matching thickness is 1.7mm. The multi-component design achieved excellent impedance matching properties. The carbon frame connects the core-shell particles to form a three-dimensional porous structure, providing multiple reflection losses. Therefore, this work provides a convenient way to design efficient and lightweight EMW absorbers with special structures.

Bridging Theory and Practice: Application of Outcome-Based Education in Product Structure Design Courses

Bridging Theory and Practice: Application of Outcome-Based Education in Product Structure Design Courses

Research on magnetic fluid precise localized lubrication thrust cylindrical roller bearing with low-friction micro-vibration and high load-bearing capacity

Abstract As the magnetic field that is difficult to be distributed in the existing magnetic fluid thrust cylindrical roller bearing structure, it is more difficult for the magnetic fluid to be evenly distributed inside the bearing raceway with the axial localized lubrication, which seriously affects the engineering application of the magnetic fluid bearing. To solve the magnetic field control problem that the magnetic fluid is uneasy to be accurately localized and adsorbed, a new type of magnetic fluid thrust cylindrical roller bearing is designed in this study, which shows good characteristics of low-friction, micro-vibration and high load-bearing capacity. The seat-ring is set as an annular raceway that can be used for magnetic fluid storage and matching with the roller lubrication system, and an annular permanent magnet is designed as an external magnetic field source to be placed below the annular raceway to adsorb the magnetic fluid on the friction surface. The structure design of the axial magnetic fluid localized lubrication bearing is reasonable, which is especially suitable for precision instruments with strict operating-conditions and precision-lubrication.

Bioinspired smart dual-layer hydrogels system with synchronous solar and thermal radiation modulation for energy-saving all-season temperature regulation

All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems. However, the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition. Herein, inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins, a smart thermal management composite hydrogel (PNA@H-PM Gel) system was subtly created though an “on-demand” dual-layer structure design strategy. The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation. Furthermore, this system demonstrates superb modulations of both the solar reflectance (ΔR = 0.74) and thermal emissivity (ΔE = 0.52) in response to ambient temperature changes, highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6 °C in summer and 6.1 °C in winter, respectively. Moreover, compared to standard building baselines, the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates. This novel solution, inspired by penguins in the real world, will offer a fresh approach for producing intelligent, energy-saving thermal management materials, and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.

Stability impact on wind turbine blades trailing edge from bonding zone modelling methods

Abstract The trailing edge of wind turbine blade will undergo a large deformation under the action of load, resulting in a higher risk of damage and failure. The finite element analysis modeling method directly affects the simulation result, furthermore impacts the result of blade structure design. Therefore, it is necessary to find out a modeling method, which is capable to reflect the stability of bonding regions more accurately. This paper aims to discuss the influences of different finite element modeling methods on the buckling stability of blade trailing edge. The influences of shell element, tetrahedron element and hexahedron element on the blade stiffness are considered. The bonding region were simulated separately by combining shell element with bonding web, shell element with tetrahedron element and shell element with hexahedron. The influences of different bonding region modeling methods on the trailing edge buckling factor were analyzed by using the eigenvalue buckling analysis method of finite element. The simulation results provided data support for the future validation of the blade trailing edge bonding area modeling method. The results show that, the tetrahedral mesh provides a higher stiffness, followed by the hexahedral mesh, and the adhesive web form has the smallest stiffness. In order to simulate the more realistic stiffness of the adhesive area at the trailing edge of the blade, adhesive web plates can be built in the flange area of the blade root and the core material area of the trial adhesive mold; The direct bonding area can be simulated employing the hexahedron mesh; The tetrahedral mesh has high stiffness and is not suitable for modeling the adhesive area at the trailing edge. Blade simulation modeling can flexibly use different adhesive forms according to actual situations, ensuring the reliability of the simulation model.