摘要:
In this study, we present a novel analysis approach for lattice composite cylindrical shells reinforced with Graphene Platelets (GPL) nanoparticles. Our primary contribution lies in the investigation of these advanced structures, incorporating nanocomposite reinforcement, orthotropic inhomogeneity, and semi-analytical methods. The lattice composite comprises an anisogrid lattice laminated shell, reinforced with functionally graded GPL. We model this structure using a global continuous orthotropic deep shell approach, integrating the Halpin-Tsai and rule of mixtures homogenization strategies to estimate equivalent mechanical properties. We derive theoretical formulations utilizing Reddy's third-order shear deformation theory and nonlinear Sanders' kinematic assumptions, tailored for deep thick shells. Nonlinear equilibrium equations are obtained using Hamilton's principle and Hooke's constitutive law, leading to linearized bifurcation equations through adjacent-equilibrium and membrane pre-buckling analysis. Our stability analysis employs a semi-analytical method combining trigonometric expansion and Chebyshev collocation functions. Validation through parametric ex -amples demonstrates the accuracy and efficiency of our approach, unveiling insights into the impact of lattice composite and geometric parameters on the stability response of these innovative structures.
摘要:
Super-hard abrasive grinding is considered to be the main approach to realize precision and ultra-precision machining of difficult-to-machine materials such as cemented carbide, engineering ceramics, titanium alloys and superalloy materials encountered. However, heavy grinding force, high grinding temperature and poor surface integrity are prone to be encountered in conventional negative rake angle grinding of difficult-to-machine materials. In response to these problems, a novel concept of positive rake angle grinding is first proposed and an abrasive grain regularly arranged binder-less polycrystalline diamond face grinding wheel with positive rake angle has been designed and fabricated by femtosecond laser ablation. To evaluate the grinding performance of the face grinding wheel with positive rake angle, grinding experiments of YG8 cemented carbide are conducted and compared with the traditional electroplated diamond grinding tool with equivalent abrasive grain dimension and distribution. The results show that compared with the conventional negative rake angle grinding, the normal and tangential forces in positive rake angle face grinding are reduced by 30.3 % similar to 36.4 % and 21.1 % similar to 29.3 %, respectively, and the ratio of normal to tangential force is reduced by 12.6 % similar to 20.3 %. The surface roughness and average depth of subsurface metamorphic layer are also significantly smaller. The laser fabricated polycrystalline diamond face grinding wheel also has better wear resistance in the grinding of cemented carbide. Therefore, it can be concluded that better ground surface quality is obtained by the novel grinding wheel with positive rake angle. The innovative grinding method can fill the research gap on the grinding mechanism of positive rake angle grinding and further enrich the grinding theory of difficult-to-machine materials.
作者机构:
[Xu, Jun; Li, Xintao; Zheng, Kaihong; Pan, Fusheng; Kang, Yuehua; Zhou, Nan] Guangdong Acad Sci, Inst New Mat, Guangzhou 510650, Peoples R China.;[Zhao, Jun] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413002, Peoples R China.;[Yang, Hong; Jiang, Bin; Pan, Fusheng] Chongqing Univ, Coll Mat Sci & Engn, Natl Engn Res Ctr Magnesium Alloys, Chongqing 400044, Peoples R China.;[Yang, Hong; Jiang, Bin; Pan, Fusheng] Chongqing Inst Adv Light Met, Chongqing 400030, Peoples R China.;[Liu, Wenjun] Chongqing Univ Technol, Coll Mat Sci & Engn, Chongqing, Peoples R China.
通讯机构:
[Jun Xu] I;[Bin Jiang] N;Institute of New Materials, Guangdong Academy of Sciences, Guangzhou, China<&wdkj&>National Engineering Research Center for Magnesium Alloys, College of Materials Science and Engineering, Chongqing University, Chongqing, China<&wdkj&>Chongqing Institute for Advanced Light Metals, Chongqing, China
摘要:
Mg-3Al-1Zn (AZ31) sheets were produced by transverse gradient extrusion (TGE) process. The flow behavior and dynamic recrystallization during extrusion were systematically analyzed. The microstructures, textures, and mechanical behavior of extruded AZ31 sheet were also analyzed and compared with conventional extruded (CE) sheet. The results showed that fine grain structure and multi-type unique textures were formed in TGE sheet because of the generation of extra flow velocity along transverse direction (TD) and flow velocity gradient along extrusion direction (ED) during extrusion. The basal poles gradually deviated away normal direction (ND) from edge to center of the TGE sheet along TD, and the largest inclination angle at center region reached around 65 degrees. Furthermore, the basal poles inclined from ED to TD 40 degrees-63 degrees, except for the center region of TGE sheet. The TGE sheet presented higher ductility and strain hardening exponent (n-value), but lower yield strength and Lankford value (r-value) in comparison with the CE sheet. Both the basal <a> slip and tensile twins were easy to be activated during deformation, and the largest elongation of 41% and the lowest yield strength of 86.5 MPa were obtained for the ED-center sample in the TGE sheet.
期刊:
Advances in Civil Engineering,2023年2023 ISSN:1687-8086
通讯作者:
Wang, YK
作者机构:
[Wang, YK; Wang, Yukui; Zhang, Dan] Hunan City Univ, Hunan Engn Res Ctr Dev & Applicat Ceramsite Concre, Yiyang 413099, Peoples R China.;[Yan, Shijun] Hunan City Univ, Coll Mech & Elect Engn, Yiyang 413000, Peoples R China.;[Zhang, Dan] Hunan City Univ, Key Lab Green Bldg & Intelligent Construct Higher, Yiyang 413000, Peoples R China.;[Hu, Zhangqi] Hunan City Univ, Coll Civil Engn, Yiyang 413099, Peoples R China.
通讯机构:
[Wang, YK ] H;Hunan City Univ, Hunan Engn Res Ctr Dev & Applicat Ceramsite Concre, Yiyang 413099, Peoples R China.
关键词:
Introduction;Materials and Methods;Results;Discussion;Conclusion;Abstract;Data Availability;Additional Points;Ethical Approval;Consent;Disclosure;Conflicts of Interests;Authors’ Contributions;Funding Statement;Acknowledgements;Acknowledgments;Supplementary Materials;Reference;Dataset Description;Dataset Files;Abstract;Introduction;Introduction and Materials;Introduction and Methods;Materials;Materials and Methods;Methods;Results;Discussion;Results and Discussion;Discussion and Conclusion;Results and Conclusion;Conclusion;Conclusions;Data Availability;Additional Points;Ethical Approval;Consent;Disclosure;Conflicts of Interest;Authors’ Contributions;Funding Statement;Acknowledgements;Supplementary Materials;References;Appendix;Abbreviations;Preliminaries;Introduction and Preliminaries;Notation;Proof of Theorem;Proofs;Analysis of Results;Examples;Numerical Example;Applications;Numerical Simulation;Model;Model Formulation;Systematic Palaeontology;Nomenclatural Acts;Taxonomic Implications;Experimental;Synthesis;Overview;Characterization;Background;Experimental;Theories;Calculations;Model Verification;Model Implementation;Geographic location;Study Area;Geological setting;Data Collection;Field Testing;Data and Sampling;Dataset;Literature Review;Related Works;Related Work;System Model;Methods and Data;Experimental Results;Results and Analysis;Evaluation;Implementation;Case Presentation;Case Report;Search Terms;Case Description;Case Series;Background;Limitations;Additional Points;Case;Case 1;Case 2 etc.;Concern Details;Retraction Details;Copyright;Related Articles
摘要:
The research group utilized the estimation model of energy consumption capacity for reinforced concrete components without axial force to assess the energy consumption capacity of 92-reinforced concrete components from the PEER database, which were subjected to axial force and bending. The study also examined the impact of design parameters, including longitudinal reinforcement ratio, transverse reinforcement ratio, axial compression ratio, and shear-span ratio, on the estimation results. The research findings revealed that when applying the estimation model of energy consumption capacity for reinforced concrete components without axial force to calculate the energy consumption capacity of reinforced concrete components with axial force, there was a significant deviation rate in the estimation of cumulative energy consumption. The relationship between the deviation rate of cumulative energy consumption and longitudinal reinforcement ratio, axial compression ratio, and shear-span ratio remained unclear. However, a more apparent linear relationship was observed with the transverse reinforcement ratio. By conducting a quantitative analysis of the transverse reinforcement ratio, the researchers proposed an modified estimation model of energy consumption capacity for reinforced concrete components with axial force. Nonetheless, the accuracy of the modified estimation model was found to be high within the range of 0–250,000 kN mm of cumulative energy consumption. For cumulative energy consumption exceeding 250,000 kN mm, further experimental and theoretical research is still required to enhance the reliability of the modified estimation model.
摘要:
BACKGROUND: Respiratory mechanics monitoring provides useful information for guiding mechanical ventilation, but many measuring methods are inappropriate for awake patients. This study aimed to evaluate the accuracy of dynamic mechanics estimation using expiratory time constant (RC(exp)) calculation during noninvasivepressure support ventilation (PSV) with air leak in different lung models. METHODS: A Respironics V60 ventilator was connected to an active breathing simulator for modeling five profiles: normal adult, restrictive, mildly and severely obstructive, and mixed obstructive/restrictive. Inspiratory pressure support was adjusted to maintain tidal volumes (V(T)), achieving 5.0, 7.0, and 10.0ml/kg body weight. PEEP was set at 5 cmH(2)O, and the back-up rate was 10bpm. Measurements were conducted at system leaks of 25-28L/min. RC(exp) was estimated from the ratio at 75% exhaled V(T) and flow rate, which was then used to determine respiratory system compliance (C(rs)) and airway resistance (R(aw)). RESULTS: In non-obstructive conditions (R(aw) ≤ 10 cmH(2)O/L/s), the C(rs) was overestimated in the PSV mode. Peak inspiratory and expiratory flow and V(T) increased with PS levels, as calculated C(rs) decreased. In passive breathing, the difference of C(rs) between different V(T) was no significant. Underestimations of inspiratory resistance and expiratory resistance were observed at V(T) of 5.0ml/kg. The difference was minimal at V(T) of 7.0ml/kg. During non-invasive PSV, the estimation of airway resistance with the RC(exp) method was accurately at V(T) of 7.0ml/kg. CONCLUSIONS: The difference between the calculated C(rs) and the preset value was influenced by the volume, status and inspiratory effort in spontaneously breathing.
关键词:
Quasi -Z -source inverter;Cascaded H -bridge;Battery energy storage;State -of -charge
摘要:
Battery energy stored quasi-Z source cascaded H-bridge based photovoltaic power generation system combines advantages of quasi-z-source inverter, cascaded H-bridge, and battery energy storage system. However, the battery state of charge imbalance between the cascaded H-bridge inverter modules would reduce the system's performance and efficiency and potentially cause the system to fail. An integrated control technique of adaptive state of charge balancing based on gain scheduling and three-phase power balance of third harmonic injection based on fundamental frequency whole zero sequences is suggested for the quasi-Z source cascaded H-bridge battery storage system. Based on the mathematical relationship between the instantaneous state of charge of battery energy stored quasi-z-source cascaded H-bridge and the voltage reference value, this method updates the proportional controller gain in each sampling period. It combines the third harmonic injection method based on the fundamental frequency zero sequence to select the optimal modulation ratio Mn. Rapid state of charge balancing is accomplished without overmodulation while increasing the power balance range and decreasing DC link voltage swings. The simulation results validate the method's usefulness. The simulation results validate the proposed control method for ensuring power distribution between each phase and achieving a balanced state of charge of the battery energy stored quasi-Z source cascaded H-bridge photovoltaic system's battery energy storage.
作者机构:
[Zhao, Yujia; Wang, Dayong; Jiang, Hao; Li, Guangyao; Cui, Junjia; Chen, Chang] Hunan Univ, State Key Lab Adv Design & Mfg Technol Vehicle, Changsha 410082, Peoples R China.;[Chen, Chang] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Peoples R China.;[Li, Guangyao] Shenzhen Res Inst Natl Engn Lab Elect Vehicles, Shenzhen Automot Res Inst, Shenzhen 518118, Peoples R China.
通讯机构:
[Jiang, H ] H;Hunan Univ, State Key Lab Adv Design & Mfg Technol Vehicle, Changsha 410082, Peoples R China.
关键词:
joining by electromagnetic flanging;aluminum alloy;steel;mechanical property;morphology
摘要:
A structure for joining thin-walled 6061-T6 aluminum alloy tube (outer tube) and Q195 steel tube (inner tube) by electromagnetic flanging process was proposed. The formation process, mechanical properties, failure modes, and morphology of the joint were investigated. The results showed that the outer tube impacted the inner tube, the flanges of the prefabricated holes on the outer tube were embedded into the prefabricated holes of the inner tube under the action of Lorentz force, and thus the mechanical locking joint was obtained. There were two tensile failure modes for the joints: Pull-out and fracture. Specifically, when the discharge energy was relatively high, the failure mode changed from pull-out to fracture. Combining the results of tensile tests and morphology observations, the maximum loads of the joints increased with the discharge energy. However, excessive discharge energy would lead to the brittle fracture of the inner tube, which was not beneficial to the service. Better discharge energy and the maximum load of the joint at this discharge energy were obtained.
摘要:
In this research, the nonlinear dynamics of a clamped circular composite plate placed on a softening elastic foundation under rapid thermal loading is investigated. In this situation, based on the amount of temperature supplied to the structure and the coefficients of softening elastic foundation, two instabilities may happen one after the other. The structure will thermally buckle and deform dynamically if the applied temperature exceeds a critical level. If the softening coefficient of the elastic foundation is critical, the structure will completely lose its stability after a certain deformation range. A polymer containing graphene platelets (GPL) makes up the system. Based on various functions, the volume fraction of fillers varies along the thickness. The system's nonlinear dynamic equations are obtained by applying Hamilton's principle and the Von-Karman theory. The transient heat conduction equation is solved by the cubic B-spline collocation (CBSC) and Crank- Nicolson procedures. The CBSC and the Newmark methods are used to solve spatially and temporally dependent governing nonlinear differential equations. Also, the Newton-Raphson method is used as a powerful tool to solve nonlinear algebraic equations. The temporal evolution, phase-plane, and post-buckling-to-maximum deflection paths are demonstrated to analyze the instabilities of the plate.
作者机构:
[Zhang, Haoran] School of Mechanical and Electrical Engineering, Hunan City University, Yiyang, 413000, China;[Chen, Guoming; Zhang, Nan] Centre for Offshore Engineering and Safety Technology, China University of Petroleum, Qingdao, 266580, China;[Wang, Rongyao] School of Mechanical and Electrical Engineering, Hunan City University, Yiyang, 413000, China<&wdkj&>Centre for Offshore Engineering and Safety Technology, China University of Petroleum, Qingdao, 266580, China
摘要:
Storms are a major threat to deep-sea mining activities on the high seas. Deep-sea mining takes a long time to prepare to avoid storms, and in some cases it is inevitable to evacuate to avoid storms with risers hung-off. In this work, the evacuation process with risers hung-off is studied, and mechanical properties such as stress and upper rotation of the mining riser system during the process are analyzed. Operation parameters such as speed and heading suitable for evacuation are studied. Evacuation routes of mining ship are optimized based on an improved A* algorithm, and the influencing factors of evacuation operations are analyzed. Research findings can provide guidance for decision-making related to storm avoidance in deep-sea mining and improve the safety of the mining system in the evacuation process.
期刊:
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films,2023年41(6):063110 ISSN:0734-2101
通讯作者:
Xiao, BJ
作者机构:
[Xiao, Baijun] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Hunan, Peoples R China.;[Zhang, Teng Fei] Anhui Univ Technol, Key Lab Green Fabricat & Surface Technol Adv Met M, Minist Educ, Maanshan, Peoples R China.
通讯机构:
[Xiao, BJ ] H;Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Hunan, Peoples R China.
摘要:
Wear resistance is a critical property of tool coatings for high-speed machining, which depends on mechanical properties and oxidation resistance of the coatings. Many works have demonstrated that AlTiSiN coating has good mechanical properties. Additionally, AlCrN coating exhibits excellent oxidation resistance. The multilayered structure has proved to improve comprehensive properties of the coatings. Therefore, AlCrN/AlTiSiN multilayer coating has a high potential to be used in machining applications. This paper focuses on the high-temperature tribological behavior of AlCrN/AlTiSiN multilayer coating. The results show that AlCrN/AlTiSiN coating exhibits good to acceptable wear resistance up to 800 degrees C. Meanwhile, AlCrN/AlTiSiN coating also displays the lowest friction coefficient of similar to 0.5 and a wear rate of 1.8 x 10(-6) mm(3)/N m at 800 degrees C, which is about 58.13% and 64.0% lower than that of AlCrN and AlTiSiN coatings, respectively. The imaging and composition analysis of the high-temperature wear tracks allowed for explaining the differences in wear mechanisms. At 800 degrees C, a dense thin tribofilm is formed on the surface of AlCrN/AlTiSiN coating, which acts as a glaze layer to impede wear. It provides a strategy for enhancing the wear resistance of monolayer coating in high temperatures, which combines the advantages of both high oxidation resistance of one layer and high hardness of the other layer.
通讯机构:
[Wang, CG ] H;Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413002, Peoples R China.
关键词:
Side milling;ZK61M magnesium alloy;Surface quality;Corrosion resistance properties
摘要:
The milling parameters have an important influence on machining performance and surface quality of metal materials. In this paper, the differences in machining and corrosion resistance properties of ZK61M plates under different processing parameters were analyzed by side milling. The milling process was simulated to explore the change laws of milling temperature and milling force. The hardness of machined surface was examined by Vikers hardness tester. The surface quality and the corrosion performances under different spindle speeds were observed by 3D ultra-depth of field microscope. The results showed that the milling temperature was increased as spindle speed and feed speed increased. The influence of spindle speed and feed speed on milling force along the milling direction and the tool direction was significant different. The milled surface had better quality when the spindle speed increased or the feed speed decreased. The hardness standard deviation of machined surface was decreased as the surface quality became better. Besides, it was summarized how spindle speed played a role in corrosion resistance performance by affecting residual stress and metal oxides.
期刊:
Journal of Manufacturing Processes,2023年101:795-806 ISSN:1526-6125
通讯作者:
Cui, JJ
作者机构:
[Li, Guangyao; Cui, JJ; Zhu, Jiapei; Cui, Junjia; Chen, Chang; Jiang, Hao; Liu, Quanxiaoxiao] Hunan Univ, State Key Lab Adv Design & Mfg Technol Vehicle, Changsha 410082, Peoples R China.;[Chen, Chang] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Peoples R China.;[Li, Guangyao] Beijing Inst Technol, Shenzhen Automot Res Inst, Shenzhen Res Inst, Natl Engn Lab Elect Vehicles, Shenzhen 518118, Peoples R China.
通讯机构:
[Cui, JJ ] H;Hunan Univ, State Key Lab Adv Design & Mfg Technol Vehicle, Changsha 410082, Peoples R China.
关键词:
Magnetic pulse spot welding;Aluminium alloy sheet;Mechanical property;Micro-morphology
摘要:
Magnetic pulse spot welding (MPSW) is a safe, efficient and environmentally friendly process, which is very suitable for joining aluminium alloys. AA5052 aluminium alloy sheets were joined by MPSW. Specifically, the bump on the flyer plate was driven to impact the parent plate at high velocity to achieve metallurgical bonding. The formation process, mechanical properties and micro-morphology of the joint were studied. The results showed that the bump of the flyer plate impacted the parent plate at high velocity caused by Lorentz force to form welding seam. The shape of the welding seam was two incompletely continuous symmetrical elliptical arcs due to the different welding velocities and welding angles in each zone. The strength of the joint was higher than that of the base metal at appropriate process parameters. Specifically, the relatively better process parameters were welding gap of 1.4 mm, welding diameter of 16 mm and discharge energy of 36 kJ. The maximum loads of tensile shear and cross-tension were 4887 N, 1744 N. There were a large amount of dimples at the fracture of welding seam, and the toughness of joint was good.