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Microstructure and mechanical performance of AZ31/6061 lap joints welded by laser-TIG hybrid welding with Zn-Al alloy filler metal
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作者 Xinze Lv Liming Liu 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第8期3325-3338,共14页
A series of Zn-xAl(x=0-35 wt.%)alloy filler metals were designed to join AZ31 Mg alloy to 6061 Al alloy by laser-TIG hybrid welding.The effect of Al content on the wettability of filler metals,microstructure evolution... A series of Zn-xAl(x=0-35 wt.%)alloy filler metals were designed to join AZ31 Mg alloy to 6061 Al alloy by laser-TIG hybrid welding.The effect of Al content on the wettability of filler metals,microstructure evolution and strength of joint was investigated.The results indicated that the strength of joints was improved with the increase of Al content in filler metals.When Zn-15Al filler was used,the ultimate fracture load reached the maximum of 1475.3 N/cm,which was increased by 28%than that with pure Zn filler.The reason is that the Al element acts as a"reaction depressant"in filler metal,which contributes to inhibiting the dissolution of Mg base metal and the Mg-Zn reaction.The addition of appropriate quantity of Al element promoted the precipitation of Al-rich solid solution instead of Zn solid solution.The MgZn_(2) IMCs have lower lattice mismatch with Al solid solution than Zn solid solution,thus the strength of joints is improved.However,the excessive addition of Al caused the formation of brittle Mg32(Al,Zn)49 ternary compounds,leading to the deterioration of joint performance. 展开更多
关键词 Laser-TIG hybrid welding Mg-Al dissimilar joint Intermetallic compounds MICROSTRUCTURE FRACTURE
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Joint Active and Passive Beamforming Design for Hybrid RIS-Aided Integrated Sensing and Communication
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作者 Chu Hongyun Yang Mengyao +1 位作者 Pan Xue Xiao Ge 《China Communications》 SCIE CSCD 2024年第10期101-112,共12页
Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink... Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions. 展开更多
关键词 alternating optimization fractional programming hybrid reconfigurable intelligent surface integrated sensing and communication joint active and passive beamforming
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Study on the Characteristics of A New Hybrid Mooring System for DualPlatform Joint Operations 被引量:1
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作者 SHEN Zhong-xiang YUAN Zhao-jun +1 位作者 LI Hong-bin ZHU Chen-yang 《China Ocean Engineering》 SCIE EI CSCD 2023年第3期506-518,共13页
As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing attention.Dual-platform joint operation requires smaller relative motion between the two sub-platforms,w... As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing attention.Dual-platform joint operation requires smaller relative motion between the two sub-platforms,which is normally difficult to be satisfied by the traditional mooring system.Therefore,a new hybrid mooring system is developed and studied in this article.To ensure safety during platform movements,both the number of anchor chains and the relative motion between the two sub-platforms are reduced in the new hybrid mooring system.By performing numerical simulations based on three-dimensional potential flow theory in AQWA and physical experiments,the performances of both the new hybrid and traditional mooring systems under two different wave conditions(i.e.,working wave and freak wave conditions) are systematically investigated.Regarding the new hybrid mooring system,the relative stability between the two sub-platforms of the new system is better,and the platforms can restore stability faster when affected by freak waves. 展开更多
关键词 dual-platform joint operation platform relative stability hybrid mooring system freak wave
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Hybrid finite-discrete element modelling of asperity degradation and gouge grinding during direct shearing of rough rock joints 被引量:10
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作者 H. Y. Liu Haoyu Han +1 位作者 H. M. An J. J. Shi 《International Journal of Coal Science & Technology》 EI 2016年第3期295-310,共16页
A hybrid finite-discrete element method was implemented to study the fracture process of rough rock joints under direct shearing. The hybrid method reproduced the joint shear resistance evolution process from asperity... A hybrid finite-discrete element method was implemented to study the fracture process of rough rock joints under direct shearing. The hybrid method reproduced the joint shear resistance evolution process from asperity sliding to degradation and from gouge formation to grinding. It is found that, in the direct shear test of rough rock joints under constant normal displacement loading conditions, higher shearing rate promotes the asperity degradation but constraints the volume dilation, which then results in higher peak shear resistance, more gouge formation and grinding, and smoother new joint surfaces. Moreover, it is found that the joint roughness affects the joint shear resistance evolution through influencing the joint fracture micro mechanism. The asperity degradation and gouge grinding are the main failure micro-mechanism in shearing rougher rock joints with deeper asperities while the asperity sliding is the main failure micro-mechanism in shearing smoother rock joints with shallower asperities. It is concluded that the hybrid finite-discrete element method is a valuable numerical tool better than traditional finite element method and discrete element method for modelling the joint sliding, asperity degradation, gouge formation, and gouge grinding occurred in the direct shear tests of rough rock joints. 展开更多
关键词 hybrid FEM-DEM Rock joint Asperity sliding Asperity shearing Fragment grinding
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Numerical Optimization by Finite Element Method of Stainless Steel/Glass-Epoxy Composite Bolted Joint under Tension and Compression
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作者 Christian Schmitt Arnaud Kremeur +1 位作者 Pawel Lipinski Julien Capelle 《Engineering(科研)》 2024年第4期102-122,共21页
The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in... The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in each component of the bolted join. The multi-material assembly was based on the principle of double lap bolted joint. It was composed of a symmetrical balanced woven glass-epoxy composite material plate fastened to two stainless sheets using a stainless pre-stressed bolt. In order to optimize the design and the geometry of the assembly, ten configurations were proposed and studied: a classical simple bolted joint, two joints with an insert (a BigHead<sup>R</sup> insert and a stair one) embedded in the composite, two “waved” solutions, three symmetrical configurations composed of a succession of metallic and composites layers, without a sleeve, with one and with two sleeves, and two non-symmetrical constituted of metallic and composites layers associated with a stair-insert (one with a sleeve and one without). A tridimensional Finite Element Method (FEM) was used to model each configuration mentioned above. The FE models taked into account the different materials, the effects of contact between the different sheets of the assembly and the pre-stress in the bolt. The stress state was analyzed in the composite part. The concept of stress concentration factor was used in order to evaluate the stress increase in the highly stressed regions and to compare the ten configurations studied. For this purpose, three stress concentration factors were defined: one for a monotonic loading in tension, another for a monotonic loading in compression, and the third for a tension-compression cyclic loading. The results of the FEM computations showed that the use of alternative metallic and composite layers associated with two sleeves gived low values of stress concentration factors, smaller than 1.4. In this case, there was no contact between the bolt and the composite part and the most stressed region was not the vicinity of the hole but the end of the longest layers of the metallic inserts. 展开更多
关键词 Bolted joint Glass-Epoxy Composite CLEARANCE hybrid Steel-Composite
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Low Complexity Joint Hybrid Precoding for Millimeter Wave MIMO Systems 被引量:14
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作者 Mingyang Cui Weixia Zou 《China Communications》 SCIE CSCD 2019年第2期49-58,共10页
In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, ... In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization. 展开更多
关键词 MILLIMETER wave MIMO 5G joint hybrid PRECODING low complexity
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Wettability, microstructure and properties of 6061 aluminum alloy/304 stainless steel butt joint achieved by laser-metal inert-gas hybrid welding-brazing 被引量:7
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作者 Jun-yu XUE Yuan-xing LI +1 位作者 Hui CHEN Zong-tao ZHU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第10期1938-1946,共9页
Laser-metal inert-gas(MIG)hybrid welding-brazing was applied to the butt joint of 6061-T6 aluminum alloy and 304 stainless steel.The microstructure and mechanical properties of the joint were studied.An excellent join... Laser-metal inert-gas(MIG)hybrid welding-brazing was applied to the butt joint of 6061-T6 aluminum alloy and 304 stainless steel.The microstructure and mechanical properties of the joint were studied.An excellent joint-section shape was achieved from good wettability on both sides of the stainless steel.Scanning electron microscopy,energy-dispersive spectroscopy and X-ray diffractometry indicated an intermetallic compound(IMC)layer at the 6061-T6/304 interface.The IMC thickness was controlled to be^2μm,which was attributed to the advantage of the laser-MIG hybrid method.Fe3Al dominated in the IMC layer at the interface between the stainless steel and the back reinforcement.The IMC layer in the remaining regions consisted mainly of Fe4Al13.A thinner IMC layer and better wettability on both sides of the stainless steel were obtained,because of the optimized energy distribution from a combination of a laser beam with a MIG arc.The average tensile strength of the joint with reinforcement using laser-MIG hybrid process was improved to be 174 MPa(60%of the 6061-T6 tensile strength),which was significantly higher than that of the joint by traditional MIG process. 展开更多
关键词 WELDING-BRAZING laser-metal inert-gas hybrid welding butt joint microstructure
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Effect Mechanisms of Hygrothermal Environments on Failure of Single-Lap and Double-Lap CFRP-Aluminum Bolted Joints 被引量:1
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作者 Meijuan Shan Libin Zhao +2 位作者 Wei Huang Fengrui Liu Jianyu Zhang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第4期101-127,共27页
The high demands for load-carrying capability and structural efficiency of composite-metal bolted joints trigger in-depth investigations on failure mechanisms of the joints in hygrothermal environments.However,few stu... The high demands for load-carrying capability and structural efficiency of composite-metal bolted joints trigger in-depth investigations on failure mechanisms of the joints in hygrothermal environments.However,few studies have been presented to exhaustively reveal hygrothermal effects on the failure of CFRP-metal bolted joints,which differ from CFRP-CFRP or metal-metal bolted joints because of the remarkably different material properties of CFRPs and metals.In this paper,hygrothermal effects on tensile failures of single-lap and double-lap CFRP-aluminum bolted joints were experimentally and numerically investigated.A novel numerical model,in which a hygrothermal-included progressive damage model of composites was established and elastic-plastic models of metals were built,was proposed to predict the failures of the CFRP-metal bolted joints in hygrothermal environments and validated by corresponding experiments.Different failure mechanisms of single-lap and double-lap CFRP-aluminum bolted joints,under 23°C/Dry and 70°C/Wet conditions,were revealed,respectively.It follows that both the collapse failures of the single-lap and double-lap bolted joints were dominated by the bearing failure of the CFRP hole laminate in the two conditions,indicating that the hygrothermal environment did not change the macro failure modes of the joints.However,the hygrothermal environment considerably shortened the damage propagation processes and reduced the strength of the joints.Besides,the hygrothermal environment weakened the load-transfer capability of the single-lap joint more severely than the double-lap joint because it aggravated the secondary bending effects of the single-lap joint obviously. 展开更多
关键词 CFRP-metal hybrid structure bolted joint hygrothermal environment effect mechanism numerical model
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Research review on steel–concrete composite joint of railway hybrid girder cable-stayed bridges 被引量:2
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作者 Zhou Shi Jiachang Gu +1 位作者 Yongcong Zhou Ying Zhang 《Railway Sciences》 2022年第2期241-259,共19页
Purpose–This study aims to research the development trend,research status,research results and existing problems of the steel–concrete composite joint of railway long-span hybrid girder cable-stayed bridge.Design/me... Purpose–This study aims to research the development trend,research status,research results and existing problems of the steel–concrete composite joint of railway long-span hybrid girder cable-stayed bridge.Design/methodology/approach–Based on the investigation and analysis of the development history,structure form,structural parameters,stress characteristics,shear connector stress state,force transmission mechanism,and fatigue performance,aiming at the steel–concrete composite joint of railway long-span hybrid girder cable-stayed bridge,the development trend,research status,research results and existing problems are expounded.Findings–The shear-compression composite joint has become the main form in practice,featuring shortened length and simplified structure.The length of composite joints between 1.5 and 3.0 m has no significant effect on the stress and force transmission laws of the main girder.The reasonable thickness of the bearing plate is 40–70 mm.The calculation theory and simplified calculation formula of the overall bearing capacity,the nonuniformity and distribution laws of the shear connector,the force transferring ratio of steel and concrete components,the fatigue failure mechanism and structural parameters effects are the focus of the research study.Originality/value–This study puts forward some suggestions and prospects for the structural design and theoretical research of the steel–concrete composite joint of railway long-span hybrid girder cable-stayed bridge. 展开更多
关键词 RAILWAY hybrid girder cable-stayed bridge Steel-concrete composite joint STRUCTURE Stress characteristics REVIEW
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Dimensioning of Punctiform Metal-Composite Joints: A Section-Force Related Failure Criterion
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作者 Holger Seidlitz Lars Ulke-Winter +1 位作者 Colin Gerstenberger Lothar Kroll 《Open Journal of Composite Materials》 2014年第3期157-172,共16页
Reliable line production processes and simulation tools play a central role for the structural integration of thermoplastic composites in advanced lightweight constructions. Provided that material-adapted joining tech... Reliable line production processes and simulation tools play a central role for the structural integration of thermoplastic composites in advanced lightweight constructions. Provided that material-adapted joining technologies are available, they can be applied in heavy-duty multi-material designs (MMD). A load-adapted approach was implemented into the new fully automatic and fault-tolerant thermo mechanical flow drill joining (FDJ) concept. With this method it is possible to manufacture reproducible high strength FRP/metal-joints within short cycle times and without use of extra joining elements for the first time. The analysis of FDJ joints requires a simplified model of the joint to enable efficient numerical simulations. The present work introduces a strategy in modeling a finite-element based analogous-approach for FDJ-joints with glass fiber reinforced polypropylene and high-strength steel. Combined with a newly developed section-force related failure criterion, it is possible to predict the fundamental failure behavior in multi-axial stress states. The functionality of the holistic approach is illustrated by a demonstrator that represents a part of a car body-in-white structure. The comparison of simulated and experimentally determined failure loads proves the applicability for several combined load cases. 展开更多
关键词 Composites Multi-Material-Design hybrid Joining FAILURE CRITERION FDJ joint
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Numerical analysis of temperature profile and weld dimensions in laser + GMAW hybrid welding of aluminum alloy T-joint
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作者 胥国祥 武传松 +1 位作者 秦国梁 王旭友 《China Welding》 EI CAS 2013年第3期51-55,共5页
The temperature fields in the transient state and weld dimensions in laser + gas metal arc welding (GMAW) hybrid welding of aluminum alloy T-joint for different welding conditions were calculated using the develope... The temperature fields in the transient state and weld dimensions in laser + gas metal arc welding (GMAW) hybrid welding of aluminum alloy T-joint for different welding conditions were calculated using the developed heat source model, and the effect of welding speed on them was analyzed. The results show that the temperature field for the first weld pass only shows the feature of GMAW and the one for the second weld pass has the characteristics of both laser welding and GMAW. Welding speed can affect greatly weld dimensions and temperature distribution. When welding speed reaches 3.5 m/min, the fusion zones of two weld passes are separated and the maximum peak temperature of thermal cycle on the workpiece surface decreases largely. 展开更多
关键词 hybrid welding aluminum alloy temperature field T-joint numerical simulation
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Joint decision-making of virtual module formation and scheduling considering queuing time
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作者 Liang Mei Liu Yue Shilun Ge 《Data Science and Management》 2023年第3期134-143,共10页
Formation and scheduling are the most important decisions in the virtual modular manufacturing system;however,the global performance optimization of the system may be sacrificed via the superposition of two independen... Formation and scheduling are the most important decisions in the virtual modular manufacturing system;however,the global performance optimization of the system may be sacrificed via the superposition of two independent decision-making results.The joint decision of formation and scheduling is very important for system design.Complex and discrete manufacturing enterprises such as shipbuilding and aerospace often comprise multiple tasks,processes,and parallel machines,resulting in complex routes.The queuing time of parts in front of machines may account for 90%of the production cycle time.This study established a weighted allocation model of a formation-scheduling joint decision problem considering queuing time in system.To solve this nondeterministic polynomial(NP)problem,an adaptive differential evolution-simulated annealing(ADE-SA)algorithm is proposed.Compared with the standard differential evolution(DE)algorithm,the adaptive mutation factor overcomes the disadvantage that the scale of DE’s differential vector is difficult to control.The selection strategy of the SA algorithm compensates for the deficiency that DE’s greedy strategy may fall into a local optimal solution.The comparison results of four algorithms of a series of random examples demonstrate that the overall performance of ADE-SA is superior to the genetic algorithm,and average iteration,maximum completion time,and move time are 24%,11%,and 7%lower than the average of other three algorithms,respectively.The method can generate the joint decision-making scheme with better overall performance,and effectively identify production bottlenecks through quantitative analysis of queuing time. 展开更多
关键词 joint decision-making Queue time Virtual module hybrid algorithm
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Static and Fatigue Behavior of Hybrid Bonded/Bolted Glass Fiber Reinforced Polymer Joints Under Tensile Loading
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作者 WANG Jinxiao CHENG Bin +2 位作者 XIANG Sheng LI Sida YAN Xingfei 《Journal of Shanghai Jiaotong university(Science)》 EI 2024年第5期817-830,共14页
This paper presents the static and fatigue tests of hybrid(bonded/bolted)glass fiber reinforced polymer(GFRP)joints.Nine specimens of single-lap hybrid GFRP joints have been fabricated to study the static and fatigue ... This paper presents the static and fatigue tests of hybrid(bonded/bolted)glass fiber reinforced polymer(GFRP)joints.Nine specimens of single-lap hybrid GFRP joints have been fabricated to study the static and fatigue behaviors in the experimental campaign.The static tests of uniaxial tension loading are first conducted,from which the static ultimate bearing capacities of the joints are obtained.High-cycle fatigue tests are subsequently carried out so that the fatigue failure mode,fatigue life,and stiffness degradation of joints can be obtained.The measuring techniques including acoustic emission monitoring and three-dimensional digital image correlation have been employed in the tests to record the damage development process.The results revealed that the static strength and fatigue behavior of such thick hybrid GFRP joints were controlled by the bolted connections.The four stages of fatigue failure process are obtained from tests and acoustic emission signals analysis:cumulative damage of adhesive layer,damage of the adhesive layer,cumulative damage of GFRP plate,and damage of GFRP plate.The fatigue life and stiffness degradation can be improved by more bolts.The S-N(fatigue stress versus life)curves for the fatigue design of the single-lap hybrid GFRP joints under uniaxial tension loading are also proposed. 展开更多
关键词 glass fiber reinforced polymer(GFRP)joint hybrid bonded/bolted connection fatigue behavior acoustic emission digital image correlation
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配筋PVA-钢混杂纤维增强水泥基复合材料梁柱边节点抗震性能试验研究 被引量:1
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作者 韩建平 包有乾 许继祥 《工程抗震与加固改造》 北大核心 2024年第2期138-145,178,共9页
改善工程材料韧性和耐久性,提高框架梁柱节点抵抗变形和破坏的能力,是提高框架结构抗震韧性的有效途径之一。采用PVA-钢混杂纤维增强水泥基复合材料代替普通混凝土应用到梁柱边节点,考虑轴压比和加密区体积配箍率的影响,设计6个配筋PVA... 改善工程材料韧性和耐久性,提高框架梁柱节点抵抗变形和破坏的能力,是提高框架结构抗震韧性的有效途径之一。采用PVA-钢混杂纤维增强水泥基复合材料代替普通混凝土应用到梁柱边节点,考虑轴压比和加密区体积配箍率的影响,设计6个配筋PVA-钢混杂纤维增强水泥基复合材料、1个配筋单掺PVA纤维增强水泥基复合材料和1个钢筋混凝土梁柱边节点试件进行拟静力试验,分析其破坏形态、滞回曲线、骨架曲线、延性、耗能能力、钢筋应变和梁端塑性铰区转角,探讨混杂纤维的加入对梁柱边节点抗震性能的影响。结果表明:与钢筋混凝土节点和单掺PVA纤维增强水泥基复合材料节点相比,PVA-钢混杂纤维增强水泥基复合材料节点的承载力高、变形能力大、延性好、耗能能力强,抗震性能显著提升。当试验轴压比从0.12增加到0.24,梁端塑性铰区产生一定的外移,塑性性能发挥更充分,同时试件的变形能力、延性、耗能能力增加。在加密区体积配箍率减小的情况下,试件仍表现出良好的抗震性能。 展开更多
关键词 梁柱边节点 PVA-钢HyFRCC 轴压比 体积配箍率 抗震性能
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基于舱外航天服头盔面窗透明件的边缘复合连接技术研究
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作者 马加炉 黄庆伟 +3 位作者 李元丰 姚丽坤 陈书赢 李少松 《载人航天》 CSCD 北大核心 2024年第1期23-28,共6页
舱外航天服头盔为多层面窗结构,压力防护是其首要的防护功能,面窗与金属盔壳之间的连接方式是关键。基于舱外服头盔面窗为聚碳酸酯基材、非规则曲面、端口弧线闭合、薄壁透明等结构特点,提出了一种聚碳酸酯面窗透明件的边缘复合连接方式... 舱外航天服头盔为多层面窗结构,压力防护是其首要的防护功能,面窗与金属盔壳之间的连接方式是关键。基于舱外服头盔面窗为聚碳酸酯基材、非规则曲面、端口弧线闭合、薄壁透明等结构特点,提出了一种聚碳酸酯面窗透明件的边缘复合连接方式,并开展了结构设计、仿真分析、原理样机研制、试验验证等工作,研究结果表明:该复合连接结构稳定可靠,性能满足应用要求。 展开更多
关键词 舱外航天服 头盔面窗 聚碳酸酯 透明件 边缘复合连接
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基于混合扩张状态观测器的农田平地机液压系统反步滑模控制研究
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作者 魏新华 王庆壮 +2 位作者 吉鑫 刘成良 汪岸哲 《农业机械学报》 EI CAS CSCD 北大核心 2024年第7期37-46,共10页
为解决农田平地机液压系统在复杂地貌平地作业时控制精度低、抗干扰能力差等问题,设计了一种基于混合扩张状态观测器(HESO)的反步滑模控制器。其中,HESO基于输出反馈信号估计系统未知状态和总扰动,并在前馈通道中进行扰动补偿;基于快速... 为解决农田平地机液压系统在复杂地貌平地作业时控制精度低、抗干扰能力差等问题,设计了一种基于混合扩张状态观测器(HESO)的反步滑模控制器。其中,HESO基于输出反馈信号估计系统未知状态和总扰动,并在前馈通道中进行扰动补偿;基于快速趋近律设计的反步滑模控制器输出连续光滑的控制量,增强了系统鲁棒性,克服了系统非线性与参数不确定性问题;通过Lyapunov稳定性理论对所提出的观测器和控制器稳定性进行验证,得到误差一致有界稳定结论;通过AMESim和Matlab/Simulink联合仿真与田间试验对本文控制算法的有效性和优越性进行了验证。在两条地貌情况较为复杂波浪地中单次平地和地貌情况较为相似的两田块进行3次遍历试验表明,使用本文控制方法,平地后高程相较于平地前标高的平均绝对误差、最大绝对误差、绝对误差标准差分别为0.053、0.146、0.037 m和0.02、0.041、0.011 m,较PID算法分别降低36.35%、28.32%、31.37%和62.6%、50%、51.83%。 展开更多
关键词 农田平地机 混合扩张状态观测器 反步滑模控制 联合仿真
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露出式刚接箱型柱混合节点的抗震性能分析
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作者 潘秀珍 张远 +2 位作者 杨一玮 陈仕伟 李慎 《应用力学学报》 CAS CSCD 北大核心 2024年第4期833-842,共10页
运用ABAQUS有限元软件,分析了用于RC框架-钢结构加层混合结构的露出式刚接箱型柱节点的非线性受力性能,并在验证有限元模型正确性的基础上,深入研究了相关参数对露出式刚接节点抗震性能的影响规律,并提出设计建议。结果表明:露出式刚接... 运用ABAQUS有限元软件,分析了用于RC框架-钢结构加层混合结构的露出式刚接箱型柱节点的非线性受力性能,并在验证有限元模型正确性的基础上,深入研究了相关参数对露出式刚接节点抗震性能的影响规律,并提出设计建议。结果表明:露出式刚接箱型柱混合节点为梁塑性铰破坏,具有较强的耗能能力和塑性变形能力,但刚度退化较为严重;根据相关参数研究提出合理的设计建议,上部钢柱应尽可能采用平面内、平面外等稳定性的箱型或■字形截面柱;就论文所研究的试件来看,轴压比控制在0.16~0.40之间比较合理。 展开更多
关键词 加层混合结构 露出式刚接 混合节点 耗能能力 抗震性能
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铁路混合梁钢-混结合段受力及理论计算
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作者 施洲 张莹 +2 位作者 李英铭 何知明 时均伟 《工程力学》 EI CSCD 北大核心 2024年第S01期282-291,共10页
为研究铁路混合梁钢-混结合段结构的受力及其理论计算公式,在既有公路桥梁钢-混结合段计算公式的基础上,提出铁路混合梁钢-混结合段截面应力、顶底板剪力连接件、承压板传力验算公式;并以主跨335 m汉巴南铁路嘉陵江特大桥为研究背景,采... 为研究铁路混合梁钢-混结合段结构的受力及其理论计算公式,在既有公路桥梁钢-混结合段计算公式的基础上,提出铁路混合梁钢-混结合段截面应力、顶底板剪力连接件、承压板传力验算公式;并以主跨335 m汉巴南铁路嘉陵江特大桥为研究背景,采用有限元分析的方法探究结合段受力特性及应力纵、横向分布规律,进而开展结合段受力理论与数值计算对比分析。数值计算结果表明,结合段混凝土均处于受压状态,不同截面位置处结合段钢、混应力横向分布均存在一定的不均匀性。公式验算结果表明:结合段混凝土应力均受压,满足截面应力验算要求;剪力连接件的抗力系数介于1.30~4.49,结合段剪力连接件具有良好的安全储备;承压板抗力系数介于3.18~10.08,表明前后承压板抗力远大于计算传力荷载,并具有优化的空间。理论公式计算的结合段顶底板混凝土应力、剪力钉应力与有限元计算结果总体相近,在修正后可用于钢-混结合段的防开裂/脱离、抗剪受力计算。 展开更多
关键词 铁路混合梁 钢-混结合段 受力理论 剪力键 承压板
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PC与钢-UHPC混合式连续梁桥结合段受力分析
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作者 邵旭东 熊满华 +2 位作者 怀臣子 莫然 杨纪 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第11期126-137,共12页
针对连续箱梁桥因自重过大导致开裂严重的工程难题,提出了一种PC梁(Pre⁃stressed Concrete,PC)与钢-UHPC(Ultra-High Performance Concrete,UHPC)组合梁结合的新型混合式连续梁桥.为探明新型桥梁中UHPC层的受力特性及其对钢-混结合段传... 针对连续箱梁桥因自重过大导致开裂严重的工程难题,提出了一种PC梁(Pre⁃stressed Concrete,PC)与钢-UHPC(Ultra-High Performance Concrete,UHPC)组合梁结合的新型混合式连续梁桥.为探明新型桥梁中UHPC层的受力特性及其对钢-混结合段传力机理的影响,以滨州黄河大桥为工程背景,首先建立了Midas整体计算模型,获得了结构在承载能力极限状态下的内力,然后采用ANSYS分别建立了无UHPC层和有UHPC层两种构造的钢-混结合段有限元局部模型,对比了两个构造结合段的受力特点及传力机理,分析了UHPC层的受力特性.计算结果表明:1)除了部分应力集中区域外,新型结构各部分应力均低于强度设计值,满足设计要求;2)最不利弯矩作用下,新型结构的钢箱梁顶板最大拉应力得到显著降低,可显著延长钢结构的疲劳寿命;3)新型结构的混凝土梁顶板在交界面处的应力下降了约5%~29%,可改善混凝土开裂现象;4)UHPC层的最大拉应力和压应力均低于其设计强度,满足规范要求,且UHPC层能分担4%~10.9%的结合段截面弯矩. 展开更多
关键词 桥梁工程 混合梁结合段 数值分析 力学性能 钢-UHPC组合梁
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部分充电策略下多中心混合车队联合配送路径优化
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作者 张得志 周少宇 +2 位作者 周理昆 王煜恺 周赛琦 《铁道科学与工程学报》 EI CAS CSCD 北大核心 2024年第9期3552-3562,共11页
城市物流电动车与燃油车混合运输场景中,运输资源共享调度和充电策略联合优化方面存在不足。基于此,综合考虑客户时间窗、混合动力车队、电动车部分充电策略、多中心间联合配送机制和碳排放等实际因素,研究带时间窗和部分充电的多中心... 城市物流电动车与燃油车混合运输场景中,运输资源共享调度和充电策略联合优化方面存在不足。基于此,综合考虑客户时间窗、混合动力车队、电动车部分充电策略、多中心间联合配送机制和碳排放等实际因素,研究带时间窗和部分充电的多中心混合车队绿色车辆路径问题。以车辆固定成本、运输成本、充电成本、碳排放成本和时间惩罚成本之和最小化为目标构建优化模型,并设计混合改进遗传-变邻域搜索算法进行求解。基于湖南省某物流企业的实际数据进行仿真实验,验证了上述模型及算法的有效性,并从配送模式、车队配置和充电策略3个方面进行了敏感性分析。研究结果表明:1)联合配送模式有助于加强配送中心间的协同合作,促进运输资源共享调度,降低物流配送成本并减少碳排放,是一种经济环保的配送模式。2)电动车充电时间过长会影响客户时间满意度下降,且对纯电动车队而言,这一影响更为显著。3)混合车队相比纯电动车队具有更低的配送成本和更高的客户满意度,相比纯燃油车队在降低配送成本和减少碳排放方面更有优势。合理的车队配置不仅能减少企业运营成本,还可以同时兼顾客户利益和环境利益。4)在物流配送中采用部分充电策略能有效节省充电时间并提升客户服务体验。研究成果可为物流企业进行运输资源联合调度和配送方案优化决策提供参考依据。 展开更多
关键词 多中心联合配送 混合车队 部分充电策略 混合改进遗传-变邻域搜索 绿色车辆路径
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