检索结果-南通市图书馆

Effect of vibration frequency on primary phase and properties of grey cast iron fabricated by lost foam casting

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Foundry 2020年第1期17卷 1-7页

作者： Bo-tao Xiao Zi-tian Fan Wen-ming Jiang Jun-huai Xiang Xue-fang Yan Jiangxi Key Laboratory of Surface Engineering Jiangxi Science and Technology Normal UniversityNanchang 330013China State Key Laboratory of Material Processing and Die&Mould Technology Huazhong University of Science&TechnologyWuhan 430074China

The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary *** this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was *** results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration *** a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the *** addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix *** order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were *** results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic *** a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.

关键词： vibration frequency lost foam casting grey cast iron flake graphite properties

Research on modeling and self-excited vibration mechanism in magnetic levitation-collision interface coupling system

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 873-890页

作者： Jinghu TANG Chaofeng LI Jin ZHOU Zhiwei WU School of Mechanical Engineering&Automation Northeastern UniversityShenyang 110819China Key Laboratory of vibration and Control of Aero-Propulsion Systems of Ministry of Education of China Northeastern UniversityShenyang 110819China School of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The modeling and self-excited vibration mechanism in the magnetic levitation-collision interface coupling system are *** effects of the control and interface parameters on the system's stability are *** frequency range of self-excited vibrations is investigated from the energy point of *** phenomenon of self-excited vibrations is elaborated with the phase *** corresponding control strategies are briefly analyzed with respect to the vibration *** results show that when the levitation objects collide with the mechanical interface,the system's vibration frequency becomes larger with the decrease in the collision gap;when the vibration frequency exceeds the critical frequency,the electromagnetic system continues to provide energy to the system,and the collision interface continuously dissipates energy so that the system enters the self-excited vibration state.

关键词： magnetic levitation coupling system self-excited vibration mechanical interface vibration frequency

Cushioning Performance of a Novel Polyurethane Foam Material Applied in Fragile Packaging

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第3期37卷 487-497页

作者： Huifeng Xi Chunqiu Guo Jinbiao Yang Xiaogang Wang Bowei Wang Shiqing Huang Zhiwei Wang School of Mechanics and Construction Engineering Jinan UniversityGuangzhou510632China College of Packing Engineering Jinan UniversityZhuhai519070China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou510632China Foshan Soft Valley Technology Co. Ltd.Foshan528000China

For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other *** new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from *** and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and *** verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration ***,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness *** vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer *** finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.

关键词： Flexible polyurethane foam Packaging of fragile goods Nonlinear dynamics vibration frequency Finite element simulation

Experimental research and energy analysis of a new type of dry ice powder pneumatic rock breaking technology

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2023年第4期33卷 423-435页

作者： Xiaofei Wang Shaobin Hu Enyuan Wang Qiang Zhang Bing Liu Key Laboratory of Gas and Fire Control for Coal Mines(China University of Mining and Technology)Ministry of Education Xuzhou 221116China National Engineering Research Center for Coal Gas Control China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyXuzhou 221116China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering HoHai UniversityNanjing 210098China Tunnel and Underground Engineering Institute College of Civil and Transportation EngineeringHoHai UniversityNanjing 210098China China Electric Construction East China Survey and Design Institute Hangzhou 311122China

When the traditional drill and blast method is applied to rock crushing projects,it has strong vibration,loud noise and dust pollution,so it cannot be used in densely populated areas such as urban public *** developed a supercritical CO_(2)true triaxial pneumatic rock-breaking experimental system,and conducted laboratory and field tests of dry ice powder pneumatic *** characteristics of the blast-induced vibration velocity waveform and the evolution of the vibration velocity and frequency with the focal distance were analyzed and *** fracturing mechanism of dry ice powder pneumatic rock breaking is *** research results show that:(1)The vibration velocity induced by dry ice powder pneumatic rock breaking decays as a power function with the increase of the focal distance;(2)The vibration frequency caused by dry ice powder pneumatic rock breaking is mainly distributed in 1–120 *** to the dispersion effect,the dominant frequency of 10–30 Hz appears abnormally attenuated;(3)The traditional CO_(2)phase change fracturing energy calculation formula is also applicable to dry ice pneumatic rock breaking technology,and the trinitrotoluene(TNT)equivalent of fracturing energy is applicable to the Sadovsky formula;(4)Dry ice powder pneumatic rock breaking is shock wave and highenergy gas acting together to fracture rock,which can be divided into three stages,among which the gas wedge action of high-energy gas plays a dominant role in rock mass damage.

关键词： Dry ice powder pneumatic rock breaking Cracking mechanism Energy analysis vibration frequency

Numerical prediction of ground vibrations induced by LPG boiling liquid expansion vapour explosion(BLEVE)inside a road tunnel

在线全文

学校读者我要写书评

暂无评论

Underground Space 2023年第5期12卷 44-64页

作者： Ruishan Cheng Wensu Chen Hong Hao Jingde Li Center for Infrastructural Monitoring and Protection School of Civil and Mechanical EngineeringCurtin UniversityBentley 6102Australia Earthquake Engineering Research&Test Center Guangzhou UniversityGuangzhou 510006China

Accidental boiling liquid expansion vapour explosions(BLEVEs)caused by the bursting of liquified petroleum gas(LPG)tank inside a tunnel can induce vibrations of its surrounding geological media and threaten the stability of adjacent tunnels and ***,it is essential to understand the characteristics of vibrations induced by LPG BLEVEs inside the tunnel for the safety design of its adjacent *** to the difficulty in effectively predicting the LPG BLEVE loads,the current practice usually employs equivalent methods,e.g.,the TNT-equivalency method,in LPG BLEVE load predictions for structural response analysis,which may lead to inaccurate response *** study compares ground vibrations induced by a BLEVE inside an arched road tunnel with those induced by its equivalent TNT explosion via high-fidelity numerical *** results demonstrate that the frequency of BLEVEinduced vibrations is lower than that induced by the TNT explosion at the same scaled *** intensity of LPG BLEVE-induced vibrations at relatively small-scaled distances is lower than that of TNT explosion-induced vibrations at the same scaled distance,but becomes higher after a certain scaled distance because of the relatively low attenuation *** addition,parametric analysis is conducted to evaluate the effects of various factors on the characteristics of LPG BLEVE-induced ground *** is found that the surrounding rock type,the rock porosity,and the cover depth of the tunnel have more significant influences than the concrete grade of the tunnel *** recommendation for the tunnel design is also given based on the intensity and frequency characteristics of BLEVE-induced vibrations.

关键词： Tunnel BLEVE TNT explosion vibration intensity vibration frequency

Effect of Train Carbody's Parameters on Vertical Bending Stiffness Performance

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2016年第6期29卷 1120-1127页

作者： YANG Guangwu WANG Changke XIANG Futeng XIAO Shoune State Key Laboratory of Traction Power Southwest Jiaotong University

Finite element analysis（FEA） and modal test are main methods to give the first-order vertical bending vibration frequency of train carbody at present, but they are inefficiency and waste plenty of time. Based on Timoshenko beam theory, the bending deformation, moment of inertia and shear deformation are considered. Carbody is divided into some parts with the same length, and it＇s stiffness is calculated with series principle, it＇s cross section area, moment of inertia and shear shape coefficient is equivalent by segment length, and the fimal corrected first-order vertical bending vibration frequency analytical formula is deduced. There are 6 simple carbodies and 1 real carbody as examples to test the formula, all analysis frequencies are very close to their FEA frequencies, and especially for the real carbody, the error between analysis and experiment frequency is 0.75%. Based on the analytic formula, sensitivity analysis of the real carbody＇s design parameters is done, and some main parameters are found. The series principle of carbody stiffness is introduced into Timoshenko beam theory to deduce a formula, which can estimate the first-order vertical bending vibration frequency of carbody quickly without traditional FEA method and provide a reference to design engineers.

关键词： train carbody vertical bending vibration frequency analysis formula sensitivity analysis

Changes in the natural frequency of a ferromagnetic rod in a magnetic field due to magnetoelastic interaction

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2008年第8期29卷 1023-1032页

作者：王省哲 Key Laboratory of Mechanics on Western Disasters and Environment Lanzhou University Lanzhou 730000P.R.China

Based on the magnetoelastic generalized variational principle and Hamilton＇s principle, a dynamic theoretical model characterizing the magnetoelastic interaction of a soft ferromagnetic medium in an applied magnetic field is developed in this paper. From the variational manipulation of magnetic scale potential and elastic displacement, all the fundamental equations for the magnetic field and mechanical deformation, as well as the magnetic body force and magnetic traction for describing magnetoelastic interaction are derived. The theoretical model is applied to a ferromagnetic rod vibrating in an applied magnetic field using a perturbation technique and the Galerkin method. The results show that the magnetic field will change the natural frequencies of the ferromagnetic rod by causing a decrease with the bending motion along the applied magnetic field where the magnetoelastic buckling will take place, and by causing an increase when the bending motion of the rod is perpendicular to the field. The prediction by the mode presented in this paper qualitatively agrees with the natural frequency changes of the ferromagnetic rod observed in the experiment.

关键词： ferromagnetic rod magnetoelastic interaction generalized variational principle vibration frequency perturbation method

Characteristics of Pore Water Pressure of Saturated Silt Under Wave Loading

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2010年第1期24卷 161-172页

作者：高玉峰张健沈扬闫俊 Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Geotechnical Research Institute of Hohai University Hohai University

The characteristics of dynamic stress in the seabed under wave loading are constant principal stress and continuous rotation of the principal stress direction. Cyclic triaxial-torsional coupling shear tests were pefformed on saturated silt by the hollow cylinder apparatus under different relative densities, deviator stress ratios and vibration frequencies to study the development of pore water pressure of the saturated silt under wave loading. It was found that the development of pore water pressure follows the trend of ＂fast - steady - drastic＂. The turning point from fast to steady stage is not affected by relative density and deviator stress ratio. However, the turning point from steady to drastic stage relies on relative density and deviator stress ratio. The vibration cycle for the liquefaction of saturated silt decreases with increasing deviator stress ratio and increases with relative density. The vibration cycle for the liquefaction of the saturated silt increases with vibration frequency and reaches a peak value, after which it decreases with increasing vibration frequency for the relative density of 70%. But the vibration cycle for the liquefaction of saturated silt increases with vibration frequency for the relative density of 30%. The development of pore water pressure of the saturated silt is influenced by relative density and vibration frequency.

关键词： silt wave loading pore water pressure vibration frequency cyclic triaxial-torsional coupling shear rotation of principal stress

Individual and combined influences of main loading parameters on granite damage development under ultrasonic vibration

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2021年第12期18卷 3366-3379页

作者： ZHANG Cheng ZHAO Da-jun ZHANG Shu-lei ZHOU Yu College of Construction Engineering Jilin UniversityChangchun 130026China Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province Shaoxing UniversityShaoxing 312000China Yellow River Survey Planning and Design Institute Co.Ltd.Zhengzhou 450003China

Ultrasonic vibration technology has great potential to weaken hard *** the effect of ultrasonic vibration loading parameters is essential to accelerate the application of this technology in practical rock *** the present work,three-factor mixed-level orthogonal ultrasonic vibration rock breaking tests were conducted to investigate the influence of the main loading parameters,including confining pressure,vibration frequency,and static force,on the damage of granite *** individual and combined influences were analyzed according to the porosity increase and P-wave decrease of granite specimens using the variance analysis *** results show that the combined effect of the static force and vibration frequency mainly promotes fatigue damage of specimens,that the confining pressure determines the damage behaviour and failure mode of specimens under ultrasonic vibration,and that the confining pressure and vibration frequency are the main factors that cause the fracture concentration in the upper part of specimens,an effect mechanistically driven by the obvious load energy *** research results provide theoretical guidance for the application of ultrasonic vibration technology.

关键词： Ultrasonic vibration Granite Damage evolution Confining pressure vibration frequency Static force Combined effect