The supporting structure's dynamic stiffness has an important influence on the rotor system. However, current research is mainly limited to the stiffness of a single supporting structure. A single ...supporting structure may not meet the requirements of the rotor system in some cases. Therefore, the method of solving dynamic stiffness of combined supporting structure is presented and compared with the traditional method based on the parallel stiffness formula. The correctness of the proposed method is verified experimentally. Then, the model of rotor system is established that takes into account the combined supporting structure's dynamic stiffness. Finally, the variation of rotor system's critical speeds and vibration response under the influence of dynamic stiffness is analyzed. An experiment is carried out to verify the influence of dynamic stiffness on the critical speeds. Furthermore, the critical speeds of rotor system will decrease under the influence of dynamic stiffness.
•This paper presents a dynamic stiffness model of the combined supporting structure.•The accuracy of the proposed model is validated by experiment.•The rotor system model considering dynamic stiffness is established.•The effect of dynamic stiffness on the rotor system is verified by numerical and experimental studies.
Owing to the rapid development in additive manufacturing, the potential to fabricate intricate structures has become a reality, emphasizing the importance of designing structures conducive to ...additive manufacturing processes. A crucial consideration is the ability to design structures requiring no additional support during manufacturing. This paper employs implicit B-spline representations for self-supporting structure design by integrating a topology optimization model with self-supporting constraints derived analytically from the implicit representation. This analytical derivation for detecting overhang regions enables accurate and efficient calculation of constraints, outperforming other B-spline-based methods. Compared to the traditional voxel-based methods, the implicit B-spline representation significantly expedites the optimization process by reducing the number of design variables. Additionally, several acceleration techniques are implemented to enhance the efficiency of our method, allowing simulations of 3D models with millions of finite elements to be completed within one and half an hour, excelling other B-spline-based methods and voxel-based methods. Various numerical experiments validate its excellent performance, confirming the effectiveness and efficiency of the proposed algorithm.
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•Analytical conditions for non-self-supporting constraints are derived based on the implicit B-spline representation.•Several acceleration techniques are employed to achieve high computational performance.•The self-supporting constraints are imposed on boundary points, significantly reducing unnecessary constraint calculations.
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•NiFe-LDH nanosheets have been successfully fabricated onto acidified carbon cloth by hydrothermal process to form hierarchical structures.•3D carbon cloth with vertically arranged ...nanosheets guide uniform Li+ flux distribution, thereby inducing homogeneous Li nucleation.•Sufficient space provided by well-designed nano/microstructured carbon cloth can accommodate Li deposition, effectively alleviating the volumetric Li expansion.•Li-plated NiFe-LDH@ACC exhibits dendrite-free Li plating/stripping morphology and boosted electrochemical performance.
Lithium (Li) metal is deemed as attractive anode due to its low electrochemical potential and high theoretical capacity. Nevertheless, the uncontrollable Li dendrite growth causes safety concern and battery failure, which severely impedes the commercialization of Li metal batteries (LMBs). Herein, 3D functional matrix comprising NiFe-layered-double-hydroxide nanosheet arrays (NiFe-LDH) evenly dispersed on acidified carbon cloth (NiFe-LDH@ACC) via hydrothermal method is designed to manipulate uniform Li electrodeposition morphology. Vertical NiFe-LDH nanosheets possess high accessible surface area to supply vast Li nucleation sites, thus effectively reducing the local current density and decreasing the nucleation energy barrier to suppress Li dendrites growth, which has been validated by simulation. Moreover, 3D structure of carbon cloth provides adequate space for storing Li metal, substantially abating volume fluctuation during repeated Li plating/stripping process. Consequently, the Li@NiFe-LDH@ACC electrode manifests ultra-long lifespan over 3500 h and low-voltage hysteresis in symmetric cells. Additionally, the full cell with limited Li@NiFe-LDH@ACC anode and commercial LiFePO4 cathode (mass loading: 8.35 mg cm−2) displays good rate capacity from 0.2 C to 5 C, and can steadily operate for 75 cycles at 2 C with a capacity of 131 mAh g−1, revealing the practical feasibility of the surface modification strategy for constructing advanced Li metal anode with high safety and appealing durability.
Though a large number of nickel-based catalysts have been applied to alkaline water electrolysis, the effect of the catalyst structure on hydrogen evolution reaction (HER) is often ignored. In this ...work, aligned porous nickel electrodes (APNEs) are fabricated by ice templating and tested for HER in 1 M KOH electrolyte. Compared to isotropic porous structures, such as nickel foam and nickel fiber felt, the present anisotropic porous structure with aligned channels has a smaller pore size, larger area of electrocatalytic activity, and stronger bubble removal ability, resulting in outstanding HER performance. Three kinds of nickel powders with different diameters are also used to prepare APNEs. The results show that the particle size plays a dominant role in the structure: smaller particles lead to wider pores and thinner walls with more protuberances. The APNE-A prepared with the smallest particles shows the most outstanding HER performance, with a minimum overpotential of 101 mV at 10 mA cm−2 and a Tafel slope of 94.3 mV dec−1. And the analysis results of stability tests and electrolytic voltage efficiency further support the positive effect of the structure on HER performance.
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•Aligned porous nickel electrodes for the HER are prepared by ice templating.•The aligned porous structure facilitates hydrogen evolution more than the general.•The nickel particle size impacts on the porous structure and morphology.•The smaller particles make the better HER performance.
In the realm of non-powder printing additive manufacturing, the removal of supports from enclosed voids has long posed a formidable challenge. In response to this challenge, inspired by the ...traditional approach of designing either self-supporting or infill-supporting structures, this paper presents a novel topology optimization method that allows for the free choice between the two types of support within same enclosed voids. The infill material not only serves as a support during the additive manufacturing process but also becomes an integral component of the final design, never requiring to be removed. Firstly, a bi-directional nonlinear virtual temperature method (BN-VTM) is introduced to identify enclosed voids. The BN-VTM adds virtual heating material in regions below a predefined temperature threshold and heat-absorbing material in regions exceeding the threshold. This strategy ensures that the maximum temperature within enclosed voids adheres strictly to the specified range, enhancing the precision of enclosed void identification throughout the iterative process. On this basis, by combining the filtering/projection method, an interpolation function for enclosed void structures that encompasses both self-supporting and infill-supporting structures is developed. This function also is applied to identify overhanging interfaces within enclosed voids. Finally, by constraining the overhang angles, the proposed topology optimization method automatically determines whether to design self-supporting structures to achieve steeper boundaries or internal infill support structures within enclosed voids. The problem of minimizing compliance under material volume fraction constraints is investigated, and sensitivity analysis is derived. Several numerical and printing examples illustrate the effectiveness of the proposed method.
•Considering both self- and infill-support structures in additive manufacturing.•Identifying enclosed voids by a bi-directional nonlinear virtual temperature method.•Improving series of filtering/projection operations to build an interpolation model.•Several numerical and printing examples show the method’s effectiveness.
In this work, converting cotton fabrics into high-performance flexible carbon electrodes are achieved successfully by using traditional dyeing, flame retardant finishing and carbonization processes ...for wearable supercapacitors. The optimal carbon electrode (CCF-SP) doped with O, N, P and S heteroatoms, exhibits high surface area (643.7 m2 g−1), porous structure and good hydrophilicity. Because of electric double layer capacitance provided by carbon materials and faradaic capacitance provided by heteroatoms, the specific capacitance of CCF-SP electrode is as high as 3079.8 ± 17.9 mF cm−2 at 2 mA cm−2. After 5000 cyclic tests, residual capacitance of CCF-SP is still 99.3% of the initial value, suggesting good rate property and coulombic efficiency. In addition, flexible supercapacitor (FSC) assembled by CCF-SP electrodes exhibits an excellent energy density of 9.4 mWh cm−3 at power density of 37.5 mW cm−3. This device can power electronic gadgets at bending situation without loss of capacitance. The stunning electrochemical properties of the created carbon electrodes and its FSCs indicate that the method of heteroatoms doping combined with carbonization treatments is cheap and easy to mass produce, which can be utilized to fabricate electrodes for wearable electronic devices in the future.
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•Flexible electrodes are obtained by heteroatoms-doping and carbonization method.•Heteroatoms-doped electrodes show high heteroatoms contents and porous structure.•The carbon electrodes possess good conductivity and wettability.•Electrodes with O, N, P and S heteroatoms have excellent electrochemical traits.•The supercapacitors present a high power density and excellent cycling stability.
•ACNF/PANI/MIL-101(Cr)-NH2 with robust 3D-supporting skeleton and tertiary porous structure was manufactured.•ACNF/PANI/MIL-101(Cr)-NH2 possessed admirable adsorption capacity, adsorption kinetics ...and reusability.•Easy-to-recyclable “electrode-type” ACNF/PANI/MIL-101(Cr)-NH2 was redesigned achieving prominent removal performance.•Deductive uptake mechanism was electrostatic, hydrogen bonding and π-π interaction.
Exploiting advanced adsorbents for the elimination of the alarming level of nonsteroidal anti-inflammatory drugs (NSAIDs) pollution has sparked extensive research attention. Herein, taking acid-treated carbon nanofiber (ACNF) as composite skeleton, a unique ACNF/polyaniline/MIL-101(Cr)-NH2 (ACNF/PANI/MIL-101(Cr)-NH2) with robust 3D-supporting framework and tertiary pore structure was synthesized to remove indomethacin (IDM). Considering the large BET surface area (SBET), wide pore size distribution, highly-exposed active sites and affluent functional groups, ACNF/PANI/MIL-101(Cr)-NH2 depicted a standout adsorption capacity of 400.1 mg/g for IDM, which was far superior to most reported adsorbents. Moreover, ACNF/PANI/MIL-101(Cr)-NH2 acquired rapid adsorption kinetics, wonderful reusability and stability. Ulteriorly, inspired by the electrode fabrication craft, one easy-to-recyclable ACNF/PANI/MIL-101(Cr)-NH2 taking graphite felt (GF) as carrier was manufactured and achieved superior adsorption capacity as well as satisfactory reusability. The adsorption mechanism was appraised via Fourier-transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The experimental data disclosed that the superior adsorption capability mainly depended on the electrostatic interaction, hydrogen bonding and π-π interaction. Overall, this work sheds light on one feasible strategy to develop advanced adsorbents in practical wastewater treatment.
In this Letter, flexible capacitive pressure sensors are developed. Compared to the current mainstream design, the structure is easier to get a large deformation in the dielectric layer and its ...deformation is more controllable. Since the structure is symmetrical, it deforms uniformly and its Poisson's ratio is near zero when pressure is applied. Besides that, by moderating the structure dimension, sensors with different sensitivity and detection pressure range can be achieved. The fabrication process of these flexible sensors is mainly based on the 3D printing technology, with which the moulds of the sensor are made. The mixture of polydimethylsiloxane and hardening solution is dripped into the printed mould to form the dielectric layer. When it is completely solidified, the dielectric layer is demoulded from the mould. Four moulds with different inner sizes are printed and then four sensors are fabricated and tested. The measurement results show that the capacitance of the sensors increases when the applied pressure increases. The sensor with thinner supporting structure in the dielectric layer has higher sensitivity. The sensor with a thicker supporting structure in the dielectric layer has a larger pressure detection range. All the sensors have low hysteresis error and excellent repeatable performance.
In this communication, an easy, two-step hydrothermal synthetic protocol for the preparation of hybrid cobalt phosphate/graphite felt (Co3(PO4)2@GF) electrocatalyst is described, where Co3(PO4)2·4H2O ...is precipitated onto a 3D self-supporting graphite felt (GF). The prepared electrocatalyst, denoted hereafter as GF-Co-P, showed an onset overpotential at 370 mV for the oxygen evolution reaction (OER), which is superior to that of the standard reference material RuO2; and a Tafel slope of 133 mV dec−1 in a pH-neutral phosphate buffer solution (PBS). In addition, it exhibited excellent catalytic stability over extended run times. We revealed that surface phosphorylation greatly enhances the exposure of active cobalt sites at catalyst surfaces, and therefore promotes the charge transfer process for OER in neutral solution.
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•A scalable hydrothermal process realizes the surface phosphorylation of carbon host.•The Co3(PO4)2@GF shows outperformance in OER that of the reference material RuO2.•The Co3(PO4)2@GF material shows excellent life performance.
