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Discharge and post-explosion behaviors of electrical explosion of conductors from a single wire to planar wire array

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Plasma Science and technology 2022年第1期24卷 151-164页

作者： Chen LI Ruoyu HAN Yi LIU Jinlin ZHAO Yanan WANG Feng HE Jiting OUYANG Research Center for Electrostatics and Applications Beijing Institute of TechnologyBeijing 100081People’s Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China

This work deals with an experimental study of a Cu planar wire array(PWA)in air and water under the stored energy 300-1200 J.A single Cu wire is adopted as a controlled *** configurations of PWA and a wire with the same mass(cross-section area)but the different specific surface areas(15-223 cm^(2)g^(-1))are *** transient process is analyzed using high-speed photography in combination with the results of optical emission and *** characteristics revealed that PWA always has a higher electric power peak,early but higher voltage peak,as well as faster vaporization and ionization process than the single-wire *** to three times stronger optical emission could be obtained when replacing the single-wire with PWA,indicating a higher energy-density state is ***,in both air and water,single-wire load tends to develop a transverse stratified structure,while PWA is dominated by the uneven energy deposition among ***,the synchronism and uniformity of the PWA explosion are discussed.

关键词： electrical explosion wire array metal plasma plasma radiation shock wave

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Reliability Analysis of Transmission Tower Based on Unscented Transformation Under Ice and Wind Loads

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ENERGIES 2024年第22期17卷 5604-5604页

作者： Chen, Jianghong Zhao, Xiaohan Shi, Kanghao Ao, Zhiqiang Zheng, Xinchao China Three Gorges Univ Coll Elect Engn & New Energy Yichang 443002 Peoples R China Hubei Prov Engn Technol Res Ctr Power Transmiss Li Yichang 443002 Peoples R China

Due to the complexity of the transmission tower structure and the correlation between wind and ice loads in the actual project, it is difficult to analyze the reliability of transmission towers with traditional methods. To solve this problem, the unscented transformation (UT) principle is presented concisely and used in the reliability analysis of transmission towers in this paper. Moreover, the finite element model of the target transmission tower is created. The reliability indices of the transmission tower under various loading cases are evaluated using UT and analyzed relative to the outcomes of the Monte Carlo method (MCS). Lastly, by analyzing and validating a wine-cup shape tangent tower, the simulation results show that the UT yields reliability indices with less than 6% relative error compared with MCS results for the transmission towers with lower reliability, which are more important in engineering. Variations in error caused by the change in correlation coefficients among variables are small. Consequently, the efficiency of calculations is improved by the UT-based reliability calculations for transmission towers in the case of correlated variables, which better meet engineering application requirements. It is proved that the method of reliability analysis for transmission towers based on the UT is applicable.

关键词： transmission tower unscented transformation method reliability index wind load Monte Carlo method

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Brain-wide dendrites in a near-optimal performance of dynamic range and information transmission

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SCIENTIFIC REPORTS 2023年第1期13卷 1-10页

作者： Lin, Congping Xu, Fan Zhang, Yiwei Huazhong Univ Sci & Technol Sch Math & Stat Wuhan Peoples R China Huazhong Univ Sci & Technol Ctr Math Sci Wuhan Peoples R China Huazhong Univ Sci & Technol Hubei Key Lab Engn Modeling & Sci Comp Wuhan Peoples R China Southern Univ Sci & Technol Dept Math Shenzhen Guangdong Peoples R China

Dendrites receive and process signals from other neurons. The range of signal intensities that can be robustly distinguished by dendrites is quantified by the dynamic range. We investigate the dynamic range and information transmission efficiency of dendrites in relation to dendritic morphology. We model dendrites in a neuron as multiple excitable binary trees connected to the soma where each node in a tree can be excited by external stimulus or by receiving signals transmitted from adjacent excited nodes. It has been known that larger dendritic trees have a higher dynamic range. We show that for dendritic tress of the same number of nodes, the dynamic range increases with the number of somatic branches and decreases with the asymmetry of dendrites, and the information transmission is more efficient for dendrites with more somatic branches. Moreover, our simulated data suggest that there is an exponential association (decay resp.) of overall relative energy consumption (dynamic range resp.) in relation to the number of somatic branches. This indicates that further increasing the number of somatic branches (e.g. beyond 10 somatic branches) has limited ability to improve the transmission efficiency. With brain-wide neuron digital reconstructions of the pyramidal cells, 90% of neurons have no more than 10 dendrites. These suggest that actual brain-wide dendritic morphology is near optimal in terms of both dynamic range and information transmission.

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The arc design principles and mechanism analysis of pumping gas hollow tungsten negative pressure arc welding or additive manufacturing

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JOURNAL OF MANUFACTURING PROCESSES 2025年 149卷 364-382页

作者： Wang, Ying Tang, Zihan Xu, Kefeng Luo, Jian Zheng, Xuejun Shanghai Univ Engn Sci Sch Math Phys & Stat Shanghai 201620 Peoples R China Shanghai Univ Engn Sci Sch Mat Sci & Engn Shanghai 201620 Peoples R China Xiangtan Univ Sch Mech Engn & Mech Xiangtan 411105 Peoples R China

To address the detrimental effects of conventional positive pressure arc (PPA) welding-particularly its destabilizing repulsive forces on molten pool dynamics in thin-walled structural fabrication-this study proposes a groundbreaking pumping gas hollow tungsten negative pressure arc (PHT-NPA) welding or additive manufacturing (AM) method. Unlike traditional PPA, which generates destabilizing repulsive effects (RE), the novel PHT-NPA technique utilizes a longitudinal magnetic field (LMF)-controlled hollow tungsten arc (HTA) to create negative pressure arc forces with intrinsic adsorption effects (AE), thereby stabilizing the molten pool. The core innovation lies in the synergistic integration of three elements: (1) a custom-designed hollow tungsten electrode for gas flow modulation, (2) an LMF-based arc adjusting mechanism to reconfigure plasma dynamics, and (3) a multi-physics-coupled arc plasma model that systematically investigates temperature fields, velocity fields, arc force, and current density distributions under arc negative pressure conditions. Through this framework, we establish quantitative mappings between LMF parameters, electrode geometry, operational approaches, and the resultant negative pressure arc forces. Critical thresholds for generating stable adsorption-dominated NPA are identified, along with the effective range of AE-driven molten pool stabilization. Furthermore, this work elucidates the formation mechanism and arc design principles of PHT-NPA welding, offering a systematic methodology for arc parameter optimization. By replacing RE-prone PPA welding with AE-enhanced PHT-NPA welding, this research provides a transformative solution to molten pool instability challenges in precision arc welding or AM, paving the way for next-generation sustainable welding manufacturing technologies in aerospace, microelectronics, and other thin-walled component applications.

关键词： Negative pressure arc welding Hollow tungsten arc Pumping gas method Adsorption effect Parameter threshold Arc design principle

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Review of laser cladding coating on wear and fatigue of railway wheels/rails

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MATERIALS SCIENCE AND technology 2024年第9期40卷 651-664页

作者： Yang, Kaiqin Zhang, Tianli Zhu, Zhiming Xu, Lianyong Lin, Sanbao Kou, Sindo Tillmann, Wolfgang Shanghai Univ Engn Sci Sch Mat Sci & Engn Shanghai 201620 Peoples R China Tsinghua Univ Dept Mech Engn Beijing Peoples R China Tianjin Univ Sch Mat Sci & Engn Tianjin Peoples R China Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin Peoples R China Univ Wisconsin Dept Mat Sci & Engn Madison WI USA Tech Univ Dortmund Inst Mat Engn Dortmund Germany

With the rapid development of high-speed railway, wheel/rail premature wear and fatigue cracks occur frequently. Laser cladding high-quality coatings with high wear resistance and fatigue resistance on the damaged surface of wheel/rail can prolong its service life. In this review, the latest research progress of laser cladding Fe-based, Co-based and Ni-based coatings on the wear and fatigue of railway wheels/rails at home and abroad is reviewed. It is concluded that the wear resistance and fatigue resistance of Co-based alloy coatings are better than those of other alloy coatings. Adding strengthening elements to alloy powders can improve the welding process and improve the comprehensive properties of the coatings. Additionally, the laser cladding of railway wheel/rail is further envisaged as well.

关键词： laser cladding alloy coating railway wheel/rail wear fatigue

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Pre-oxidized mesophase pitch modified phenolic composites with mosaic-structured char layers and excellent ablation resistance

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COMPOSITES PART B-engineering 2023年 257卷

作者： Huang, Yisen Zhang, Haoruo Liu, Zhuodong Zhou, Chuxiang Yan, Liwei Zou, Huawei Chen, Yang Liang, Mei Sichuan Univ Polymer Res Inst State Key Lab Polymer Mat Engn Chengdu 610065 Peoples R China

Currently, phenolic resin (PR) is widely used as a matrix for the polymer-based ablative materials in aerospace industry. In this paper, pre-oxidized mesophase pitch (OMP) modified boron phenolic composites (OMPBPR) and their fiber-reinforced composites were prepared. PLM and SEM analyses showed that the OMP can co-carbonize with resin matrix to construct a mosaic-structured char layer incorporated pitch-based graphitic carbon during ablation. Furthermore, mercury intrusion porosimeter, XRD, Raman and TEM analyses showed that the inlaid graphitic carbon can effectively hinder the growth of defects in amorphous carbon (AC) framework, while improve the graphitization degree of char layer. The results demonstrated that the linear and mass ablation rates of OMPBPR were optimally reduced by 109% and 27.1% compared to the counterpart, and the linear ablation rate of fiber-reinforced composite was also optimally reduced by 65.5%. The above results indicate that the novel OMPBPR-based composites are promising materials for application in thermal protection systems.

关键词： Polymer-matrix composites (PMCs) Thermosetting resin High-temperature properties Mesophase pitch

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Performance transformation of Co-added Sn58Bi solder joints under thermal shock conditions for interconnection packaging

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INTERMETALLICS 2025年 181卷

作者： Huang, Xi Zhang, Liang Gao, Lili Zhao, Meng Yu, Xin-Quan Lu, Quan-Bin Xiamen Univ Technol Sch Mat Sci & Engn Xiamen 361000 Peoples R China Shanghai Inst Radio Equipment Shanghai 200090 Peoples R China Zhengzhou Res Inst Mech Engn State Key Lab Adv Brazing Filler Met & Technol Zhengzhou 450001 Peoples R China

Investigating solder joint stability in electronic packaging under extreme temperature fluctuations holds significant importance. In this experiment, the stability of Co particle-reinforced Sn58Bi/Cu solder joints was studied during the thermal shock process from -55 degrees C to 125 degrees C. By comparing the Sn58Bi-xCo (x = 0, 0.3)/Cu solder joints subjected to thermal shocks(from the 200th to 1200th cycle), it was found that adding Co effectively inhibited the Bi phase coarsening in the joint. Adding Co led to the transformation of the Cu6Sn5 intermetallic compound (IMC) layer into the (Cu, Co)6Sn5 IMC layer, resulting in an increase in the growth rate of the (Cu, Co)6Sn5 layer and a decrease in the growth rate of the Cu3Sn layer. During the thermal shock process, adding Co led to the refinement of the IMC grains and the enhancement of the stability of the IMC layer. This, in turn, resulted in the inhibition of crack propagation and the delay of the occurrence of brittle fracture. The shear strength of the Co-added solder joints was consistently higher than that of the Sn58Bi solder joints.

关键词： Sn58Bi solder Co particles Thermal shock IMC layer Shear strength

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Enhanced ablation resistance of phenolic composites through the construction of a sea-island nanostructured char layer via in-situ catalytic graphitization of incorporated Salen-Ni complex

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CHEMICAL engineering JOURNAL 2023年第1期464卷

作者： Huang, Yisen Liu, Zhuodong Yan, Liwei Zou, Huawei Chen, Yang Liang, Mei Sichuan Univ Polymer Res Inst State Key Lab Polymer Mat Engn Chengdu 610065 Peoples R China

Phenolic resin (PR) are widely used as ablative thermal protection systems for aerospace applications. However, it remains a challenge to improve the ablation resistance of phenolic composites by designing the structures of char layer via a facile approach. In this paper, a Salen-Ni complex (CL) modified boron phenolic composite (CLBPR) was designed with low concentrations of Ni (0.05-0.45 wt%). The chemically incorporated Salen-Ni structures enabled the uniform distribution of Ni element, and the enhancement of graphitization degree of char layer through the significant catalytic effect. XPS, XRD, RAMAN and TEM analyses showed that the metallic Ni nanoparticles arising from Salen-Ni structures could effectively catalyze the ablated char layer to generate various type of graphitic nanostructures, and construct a sea-island nanostructured char layer during ablation. Furthermore, we found that the inlaid graphitic phases formed through Solid-Liquid-Solid mechanism in amorphous carbon (AC) can hinder the growth of defects, while improve the graphitization degree of char layer. The results demonstrated that the linear and mass ablation rates of CLBPR were reduced by 128.9% and 32.6% compared to the counterpart at 4 MW/m2. This research will provide some inspirations more or less for the development of more advanced polymer-matrix ablative composites in the future.

关键词： Phenolic composites Catalytic graphitization Nickel Ablation performance

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Nano Co-Continuous Structure Poly(imide-siloxane)/Phenolic Hybrid Resin Fabricated by Copolymerization for the Thermal Protection System

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INDUSTRIAL & engineering CHEMISTRY RESEARCH 2023年第27期62卷 10477-10486页

作者： Yuan, Quan Wang, Yuan Huang, Yisen Tian, Jinfeng Heng, Zhengguang Liang, Mei Chen, Yang Zou, Huawei Sichuan Univ State Key Lab Polymer Mat Engn Polymer Res Inst Chengdu 610065 Peoples R China

Organic-inorganic hybridizationis an importantway to improvethe ablation resistance of phenolic resin (PR). However, it is difficultto form a continuous inorganic liquid film on the resin surface duringablation, thus limiting the further improvement of ablation *** this work, a new poly(imide-siloxane) (PIS) was designed by introducingimide rings and terminal ethoxy groups into the main chain of silicone,and then it was introduced into PR. The imide rings can increase thepolarity of the chain, and the terminal ethoxy groups can react withhydroxyl groups in PR, which can improve the compatibility of PISwith PR. SEM and AFM showed that nano co-continuous and sea-islandstructures of hybrid resins were prepared, respectively. Then, theinfluence of different structures on thermal stability and ablation-resistantproperties was investigated by using TGA, tube furnace heat treatment,and oxyacetylene ablation test. Compared to the sea-island structure,the nano co-continuous structure of resin can form a continuous anddense SiO2 film in situ, giving the resin superior thermalstability and ablation-resistant properties. The present work providesan available way to manipulate hybrid resin's phase structureand develop high-performance ablation-resistant resin in aerospaceapplications.

关键词： Ablation Chemical structure Layers Organic polymers Polyimides

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Surface melt nitriding and strengthening mechanism of plasma torched M50 bearing steel

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JOURNAL OF MANUFACTURING PROCESSES 2024年 124卷 1214-1226页

作者： Zhang, Hainan Yu, Jianbo Yang, Zhigang Zhang, Xiaoxin Dong, Ying Jiang, Jintao Wang, Jiang Ren, Zhongming Shanghai Univ Sch Mat Sci & Engn State Key Lab Adv Special Steel Shanghai 200444 Peoples R China Shijiazhuang Tiedao Univ Engn Res Ctr Matamat & Microdevices Sch Mat Sci & Engn Shijiazhuang 050043 Peoples R China

This paper presents a new plasma torch nitriding technology for the first time to realize the surface nitriding of bearing steel for strengthening. By adjusting the plasma torch current parameters in the range of 120-160 A, M50 bearing steel was carried out at a nitriding speed of 2 s/cm(2). After nitriding, the nitrogen content was increased from 0.00732 wt% in the original M50 steel up to 0.416 wt%, and the thickness of the nitrided layer was up to 2.51 mm. FeN0.076, Fe2N and Fe3N phases were formed in the steel, which was beneficial to increase the hardness and strength of bearing steel. The Vickers hardness of the original M50 bearing steel was 241 HV0.2. However, the highest surface hardness of specimen after nitriding was increased up to 778 HV0.2, which was attributed to the effect of sub-surface hardness strengthening within 2 mm from the depth of nitride surface. The average wear coefficient and the volumetric wear rate of the specimen after nitriding were decreased by about 32 % and 70 %, respectively. TEM observation showed that after nitriding, the structure of nitrided layer was martensite. The precipitates in the steel changed from large-sized, irregular and aggregated carbides (M23C6, M4C3 and M2C) to small-sized, spherical and uniformly distributed carbon-nitrogen composite precipitates (M-23(C, N)(6), M-7(C, N)(3)) in the steel sub-surface, but no obvious precipitates were formed on the surface of nitrided specimens. At depths of 1 mm and 2 mm, the size of the precipitates was reduced by about 68 % and 41 %, respectively, and the area of the precipitates was reduced from 18.4 % to 2.3 % and 3.7 %, respectively, compared to the original M50 bearing steel. It was concluded that the nitrided layer were strengthened synergistically with nitrogen solid solution, nitrogen-containing precipitates and martensite.

关键词： Plasma torch M50 bearing steel Nitriding Properties Precipitates Microstructure

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