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Flow Field Characteristics of Multi-Trophic Artificial Reef Based on Computation Fluid Dynamics
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作者 HUANG Junlin LI Jiao +3 位作者 LI Yan GONG Pihai GUAN Changtao XIA Xu 《Journal of Ocean University of China》 CAS CSCD 2024年第2期317-327,共11页
On the basis of computational fluid dynamics,the flow field characteristics of multi-trophic artificial reefs,including the flow field distribution features of a single reef under three different velocities and the ef... On the basis of computational fluid dynamics,the flow field characteristics of multi-trophic artificial reefs,including the flow field distribution features of a single reef under three different velocities and the effect of spacing between reefs on flow scale and the flow state,were analyzed.Results indicate upwelling,slow flow,and eddy around a single reef.Maximum velocity,height,and volume of upwelling in front of a single reef were positively correlated with inflow velocity.The length and volume of slow flow increased with the increase in inflow velocity.Eddies were present both inside and backward,and vorticity was positively correlated with inflow velocity.Space between reefs had a minor influence on the maximum velocity and height of upwelling.With the increase in space from 0.5 L to 1.5 L(L is the reef lehgth),the length of slow flow in the front and back of the combined reefs increased slightly.When the space was 2.0 L,the length of the slow flow decreased.In four different spaces,eddies were present inside and at the back of each reef.The maximum vorticity was negatively correlated with space from 0.5 L to 1.5 L,but under 2.0 L space,the maximum vorticity was close to the vorticity of a single reef under the same inflow velocity. 展开更多
关键词 artificial reef flow field characteristics computation fluid dynamics multi-trophic structure
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Dynamic mechanical characteristics of deep Jinping marble in complex stress environments
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作者 Chendi Lou Heping Xie +6 位作者 Ru Zhang Hai Ren Hao Luo Kun Xiao Yuan Peng Qiang Tan Li Ren 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第2期630-644,共15页
To reveal the dynamic mechanical characteristics of deep rocks,a series of impact tests under triaxial static stress states corresponding to depths of 300-2400 m were conducted.The results showed that both the strain ... To reveal the dynamic mechanical characteristics of deep rocks,a series of impact tests under triaxial static stress states corresponding to depths of 300-2400 m were conducted.The results showed that both the strain rates and the stress environments in depth significantly affect the mechanical characteristics of rocks.The sensitivity of strain rate to the dynamic strength and deformation modulus shows a negative correlation with depth,indicating that producing penetrative cracks in deep environments is more difficult when damage occurs.The dynamic strength shows a tendency to decrease and then increase slightly,but decreases sharply finally.Transmissivity demonstrates a similar trend as that of strength,whereas reflectivity indicates the opposite trend.Furthermore,two critical depths with high dynamically induced hazard possibilities based on the China Jinping Underground Laboratory(CJPL)were proposed for deep engineering.The first critical depth is 600-900 m,beyond which the sensitivity of rock dynamic characteristics to the strain rate and restraint of circumferential stress decrease,causing instability of surrounding rocks under axial stress condition.The second one lies at 1500-1800 m,where the wave impedance and dynamic strength of deep surrounding rocks drop sharply,and the dissipation energy presents a negative value.It suggests that the dynamic instability of deep surrounding rocks can be divided into dynamic load dominant and dynamic load induced types,depending on the second critical depth. 展开更多
关键词 Rock mechanics Split-Hopkinson pressure bar Coupled staticdynamic loading Different depths Holmquist-Johnson-Cook(HJC)model
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Dynamic Characteristics of Functionally Graded Timoshenko Beams by Improved Differential Quadrature Method
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作者 Xiaojun Huang Liaojun Zhang +1 位作者 Hanbo Cui Gaoxing Hu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第8期1647-1668,共22页
This study proposes an effective method to enhance the accuracy of the Differential Quadrature Method(DQM)for calculating the dynamic characteristics of functionally graded beams by improving the form of discrete node... This study proposes an effective method to enhance the accuracy of the Differential Quadrature Method(DQM)for calculating the dynamic characteristics of functionally graded beams by improving the form of discrete node distribution.Firstly,based on the first-order shear deformation theory,the governing equation of free vibration of a functionally graded beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam axial displacement,transverse displacement,and cross-sectional rotation angle by considering the effects of shear deformation and rotational inertia of the beam cross-section.Then,ignoring the shear deformation of the beam section and only considering the effect of the rotational inertia of the section,the governing equation of the beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam transverse displacement.Based on the differential quadrature method theory,the eigenvalue problem of ordinary differential equations is transformed into the eigenvalue problem of standard generalized algebraic equations.Finally,the first several natural frequencies of the beam can be calculated.The feasibility and accuracy of the improved DQM are verified using the finite element method(FEM)and combined with the results of relevant literature. 展开更多
关键词 Timoshenko beams functionally graded materials dynamic characteristics natural frequency improved differential quadrature method
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Analysis of mesoscopic mechanical dynamic characteristics of ballast bed with under sleeper pads
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作者 Xiong Yang Liuyang Yu +3 位作者 Xuejun Wang Zhigang Xu Yu Deng Houxu Li 《Railway Engineering Science》 EI 2024年第1期107-123,共17页
The meso-dynamical behaviour of a high-speed rail ballast bed with under sleeper pads(USPs)was studied.The geometrically irregular refined discrete element model of the ballast particles was constructed using 3D scann... The meso-dynamical behaviour of a high-speed rail ballast bed with under sleeper pads(USPs)was studied.The geometrically irregular refined discrete element model of the ballast particles was constructed using 3D scanning techniques,and the 3D dynamic model of the rail-sleeper-ballast bed was constructed using the coupled discrete element method-multiflexible-body dynamics(DEM-MFBD)approach.We analyse the meso-mechanical dynamics of the ballast bed with USPs under dynamic load on a train and verify the correctness of the model in laboratory tests.It is shown that the deformation of the USPs increases the contact area between the sleeper and the ballast particles,and subsequently the number of contacts between them.As the depth of the granular ballast bed increases,the contact area becomes larger,and the contact force between the ballast particles gradually decreases.Under the action of the elastic USPs,the contact forces between ballast particles are reduced and the overall vibration level of the ballast bed can be reduced.The settlement of the granular ballast bed occurs mainly at the shallow position of the sleeper bottom,and the installation of the elastic USPs can be effective in reducing the stress on the ballast particles and the settlement of the ballast bed. 展开更多
关键词 Under sleeper pads Ballast bed Discrete element method Mesoscopic mechanical dynamic characteristics
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Practice on Gravity-1 Rocket Dynamic Characteristics Design
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作者 BU Xiangwei SONG Yinghui HUANG Shuai 《Aerospace China》 2024年第1期9-17,共9页
Since the Dongfeng-2 missile, full-vehicle modal testing has been established as an indispensable part of the development and testing of rocket and missile models. However, as rockets have been developed larger, the c... Since the Dongfeng-2 missile, full-vehicle modal testing has been established as an indispensable part of the development and testing of rocket and missile models. However, as rockets have been developed larger, the cost and duration of such tests have significantly increased, magnifying their impact on model development. This article follows the process of the modal testing practice of the Gravity-1 rocket, reviewing and summarizing the design process of the rocket's dynamic characteristics. Initially, the article introduces common modeling techniques for launch rockets, including the mass-beam model and the hybrid element model. It then discusses the relationship between the structural dynamics model of the launch rocket and modal testing, aiming to reduce testing costs through refined structural dynamics modeling methods. Subsequently, the article describes the dynamic characteristics design process of the Gravity-1 carrier rocket, categorizes structural parameters, and studies how the selection of structural parameters affects the predicted dynamic characteristics of the rocket. Finally, it elaborates on the design of the modal testing scheme and the dynamic characteristics design based on the test data. 展开更多
关键词 Gravity-1 dynamic characteristics modal testing structural dynamics model
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Effects of Fatigue Characteristics on Static and Dynamic Performance of Eucommia Rubber Isolators
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作者 Yongsheng Peng Junfeng Yang +2 位作者 Guopei Pan Jianan Zhang Zhuo Wang 《Journal of Applied Mathematics and Physics》 2023年第7期2165-2177,共13页
This study aimed to investigate the effect of fatigue characteristics on the static and dynamic performance of Eucommia ulmoides gum isolators, and to explore the performance changes of Eucommia ulmoides gum isolators... This study aimed to investigate the effect of fatigue characteristics on the static and dynamic performance of Eucommia ulmoides gum isolators, and to explore the performance changes of Eucommia ulmoides gum isolators with different formulations. For this purpose, we used five formulations of Eucommia ulmoides gum isolators and set different fatigue test methods to study the static and dynamic performance changes of Eucommia ulmoides gum isolators with different formulations by changing the amplitude. The experimental results showed that the addition of Eucommia ulmoides gum had an impact on the performance of the isolator, and the number of fatigue cycles would lead to the hardening of the Eucommia ulmoides gum isolator and changes in its static and dynamic performance. In the range of two million vibrations, the performance change of the isolator was significant in the early stage and then tended to be flat, indicating that the impact of fatigue on the performance of the isolator would not continue to persist. It is worth noting that the study found that the addition of 30% Eucommia ulmoides gum had the least impact on the performance of the isolator under fatigue. Therefore, for long-term use of Eucommia ulmoides gum isolators, attention should be paid to their fatigue characteristics to ensure their stability and reliability. Additionally, this study provides a reference for the design and application of Eucommia ulmoides gum isolators. In summary, this study provides important reference value for a deeper understanding of the fatigue characteristics of Eucommia ulmoides gum isolators and for ensuring their stable and reliable performance. . 展开更多
关键词 Fatigue characteristics Eucommia Rubber Vibration Isolators static Performance dynamic Performance
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Mechanical behavior and failure mechanisms of rock bolts subjected to static-dynamic loads
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作者 Hongpu Kang Guiyang Yuan +4 位作者 Linpo Si Fuqiang Gao Jinfu Lou Jinghe Yang Shuangyong Dong 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第3期281-288,共8页
This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts.Employing a housemade load fram... This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts.Employing a housemade load frame to simulate various failure scenarios,pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined loads.The experimental results denote that with increased impact energy,maximum and average impact loads on rock bolts escalate significantly under pretension,initiating plastic deformation beyond a certain threshold.Despite minor reductions in the yield load due to impactinduced damage,pretension aids in constraining post-impact deformation rate and fluctuation degree of rock bolts.Moreover,impact-induced plastic deformation causes internal microstructure dislocation,fortifying the stiffness of the rock bolt support system.The magnitude of this fortification is directly related to the plastic deformation induced by the impact.These findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation,emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency. 展开更多
关键词 Rock bolt PRETENSION static and dynamic load IMPACT
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Energy mechanism of bolt supporting effect to fissured rock under static and dynamic loads in deep coal mines
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作者 Deyuan Fan Xuesheng Liu +2 位作者 Yunliang Tan Xuebin Li Shenglong Yang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第3期371-384,共14页
The stability control of fissured rock is difficult,especially under static and dynamic loads in deep coal mines.In this paper,the dynamic mechanical properties,strain rate evolution and energy dissipation of fissured... The stability control of fissured rock is difficult,especially under static and dynamic loads in deep coal mines.In this paper,the dynamic mechanical properties,strain rate evolution and energy dissipation of fissured and anchored rocks were respectively obtained by SHPB tests.It was found that bolt can provide supporting efficiency-improving effect for fissured rock against dynamic disturbance,and this effect increased quadratically with decrease in anchoring angles.Then,the energy dissipation mechanism of anchored rock was obtained by slipping model.Furthermore,bolt energy-absorbing mechanism by instantaneous tensile-shear deformation was expressed based on material mechanics,which was the larger the anchoring angle,the smaller the energy absorption,and the less the contribution to supporting efficiency improvement.On this basis,the functional relationship between energy dissipation of anchored rock and energy absorption of bolt was established.Taking the coal-gangue separation system of Longgu coal mine as an example,the optimal anchoring angle can be determined as 57.5°–67.5°.Field monitoring showed fissured rock with the optimal anchoring angle,can not only effectively control the deformation,but also fully exert the energy-absorbing and efficiency-improving effect of bolt itself.This study provides guidance to the stability control and supporting design for deep engineering under the same or similar conditions. 展开更多
关键词 static and dynamic loads Anchored rock Energy absorption Anchoring angle Engineering verification
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Research of transient rotor dynamic characteristic of magnetic liquid double suspension bearing in double collision state
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作者 刘洪美 LI Shengguo +2 位作者 SUN Chao SUN Yanan ZHAO Jianhua 《High Technology Letters》 EI CAS 2024年第2期146-157,共12页
During the operation of magnetic liquid double suspension bearing(MLDSB),due to rotor resonance,assembly error and other factor,the vibration amplitude of the rotor in resonance state exceeds the original design clear... During the operation of magnetic liquid double suspension bearing(MLDSB),due to rotor resonance,assembly error and other factor,the vibration amplitude of the rotor in resonance state exceeds the original design clearance,resulting in the collision damage between the rotor and the stator,the rotor and the casing.This paper presents a method to simulate the influence of different factors on the dynamic characteristics of 5 degrees of freedom(DOF)rotor based on the dynamic model of MLDSB.Firstly,according to the second Lagrange equation,the dynamic equation of 5 DOF rotor is derived,and the mathematical model is established.Then,based on 5 DOF rotor dynamic equation,the rotor transient dynamic equation under collision state is obtained,and the rotor transient collision dynamic simulation model is established.Finally,the key influencing factors of rotor dynamic characteristics are extracted,and the influence mapping relationship of rotor displacement,axis locus and stress distribution under different factors is simulated by using ANSYS Workbench software.The experimental results show that this method can effectively reflect the influence of various factors on the dynamic characteristics of the rotor.This method can provide theoretical reference for the design and control of MLDSB. 展开更多
关键词 displacement response axis trajectory radial excitation peak radial excitationtimes transient dynamic characteristics
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Dynamic stiffness characteristics of aero-engine elastic support structure and its effects on rotor systems:mechanism and numerical and experimental studies 被引量:4
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作者 Lei LI Zhong LUO +1 位作者 Kaining LIU Jilai ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第2期221-236,共16页
The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e.,the dynamic stiffness).However,the dynamic ... The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e.,the dynamic stiffness).However,the dynamic stiffness and its effect mechanism have been rarely incorporated in open studies of the rotor system.Therefore,this study theoretically reveals the effect mechanism of dynamic stiffness on the rotor system.Then,the numerical study and experimental verification are conducted on the dynamic stiffness characteristics of a squirrel cage,which is a common support structure for aero-engine.Moreover,the static stiffness experiment is also performed for comparison.Finally,a rotor system model considering the dynamic stiffness of the support structure is presented.The presented rotor model is used to validate the results of the theoretical analysis.The results illustrate that the dynamic stiffness reduces the critical speed of the rotor system and may lead to a new resonance. 展开更多
关键词 dynamic stiffness squirrel cage rotor system dynamic characteristic critical speed
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Experimental study of the dynamic mechanical responses and failure characteristics of coal under true triaxial confinements 被引量:2
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作者 Zhanguo Ma Pengfei Yan +3 位作者 Shixing Cheng Peng Gong Fuzhou Qi Jianguo Wang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第6期761-772,共12页
Investigations on the dynamic mechanical properties and failure mechanisms of coal under in-situ stress is essential for the prevention of dynamic disasters in deep coal mines.Thus,a modified true triaxial Hopkinson b... Investigations on the dynamic mechanical properties and failure mechanisms of coal under in-situ stress is essential for the prevention of dynamic disasters in deep coal mines.Thus,a modified true triaxial Hopkinson bar was employed to explore the dynamic mechanical behaviors of coal at different confining pressures(0–20 MPa)and strain rates(40–220 s^(-1)).The results show that the dynamic peak stress is positively correlated with lateral static pre-stressσy andσz,but negatively correlated with axial static prestressσx.At approximate strain rates,increasing the lateral static pre-stress facilitates increasing the dynamic peak stress,but the minimum lateral static pre-stress is the primary factor limiting a significant increase in dynamic peak stress of coal.Furthermore,the dynamic differential stress is linearly related to the logarithm of strain rate,and the peak strain varies linearly with strain rate.However,there is no significant correlation between confining pressure and peak strain.Moreover,X-ray CT images and photographic fracture observations of coal samples show the failure patterns under uniaxial and triaxial conditions are splitting failure and shear failure,respectively.The device provides a viable approach for fully comprehending the dynamic mechanical behaviors of rock-like material in complex stress conditions. 展开更多
关键词 COAL True triaxial SHPB test dynamic mechanical properties Failure characteristics
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Dynamic mechanical characteristics of NdFeB in electromagnetic brake 被引量:1
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作者 Lei Li Guo-lai Yang Li-qun Wang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第1期111-125,共15页
With the continuous development of artillery,the disadvantages of hydraulic recoil brakes gradually appear.At the same time,the appearance of high-performance Nd Fe B permanent magnet makes it possible to apply electr... With the continuous development of artillery,the disadvantages of hydraulic recoil brakes gradually appear.At the same time,the appearance of high-performance Nd Fe B permanent magnet makes it possible to apply electromagnetic braking technology to recoil mechanism.In this paper,prototype tests of a certain artillery were carried out to verify the feasibility of the electromagnetic brake(EMB)and obtain the electromagnetic braking force.Due to the brittleness of Nd Fe B,in order to eliminate the worry about the safety of EMB,SHPB experiments of Nd Fe B were carried out.Then,based on the assumption of uniform crack distribution,the law of crack propagation and damage accumulation was described theoretically,and the damage constitutive model suitable for brittle materials was proposed by combining the Zhu-Wang-Tang(ZWT)equation.Finally,the numerical simulation model of the artillery prototype was established and through calculation,the dynamic mechanical characteristics of Nd Fe B in the prototype were analyzed.The calculation results show that the strength of Nd Fe B can meet the requirements of the use in the working process.From the perspective of damage factor,the damage value of the permanent magnet on the far right is larger,and the damage value of the inner ring gradually decreases to the outer ring. 展开更多
关键词 Electromagnetic brake Sintered NdFeB Damage constitutive dynamic mechanical characteristics
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Physical modeling of long-term dynamic characteristics of the subgrade for medium-low-speed maglevs
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作者 Minqi Dong Wubin Wang +4 位作者 Chengjin Wang Zhichao Huang Zhaofeng Ding Zhixing Deng Qian Su 《Railway Engineering Science》 2023年第3期293-308,共16页
To investigate the dynamic characteristics and long-term dynamic stability of the new subgrade structure of medium-low-speed(MLS)maglevs,cyclic vibration tests were performed under natural and rainfall conditions,and ... To investigate the dynamic characteristics and long-term dynamic stability of the new subgrade structure of medium-low-speed(MLS)maglevs,cyclic vibration tests were performed under natural and rainfall conditions,and the dynamic response of the subgrade structure was monitored.The dynamic response attenuation characteristics along the depth direction of the subgrade were compared,and the distribution characteristics of the dynamic stress on the surface of the subgrade along the longitudinal direction of the line were analyzed.The critical dynamic stress and cumulative deformation were used as indicators to evaluate the long-term dynamic stability of the subgrade.Results show that water has a certain effect on the dynamic characteristics of the subgrade,and the dynamic stress and acceleration increase with the water content.With the dowel steel structure set between the rail-bearing beams,stress concentration at the end of the loaded beam can be prevented,and the diffusion distance of the dynamic stress along the longitudinal direction increases.The dynamic stress measured in the subgrade bed range is less than 1/5 of the critical dynamic stress.The postconstruction settlement of the subgrade after similarity ratio conversion is 3.94 mm and 7.72 mm under natural and rainfall conditions,respectively,and both values are less than the 30 mm limit,indicating that the MLS maglev subgrade structure has good long-term dynamic stability. 展开更多
关键词 Medium-low-speed maglev SUBGRADE dynamic characteristics Long-term dynamic stability Model test
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Dynamic response characteristics of a circular lined tunnel under anisotropy frost heave of overlying soil at the tunnel portal section in cold regions
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作者 ZHANG Shuo-cheng CHEN Wen-hua 《Journal of Mountain Science》 SCIE CSCD 2023年第5期1424-1440,共17页
The rapid development of traffic engineering in cold regions and its consequent problems need to be considered.In this paper,the dynamic response characteristics of the tunnel portal section in cold regions with harmo... The rapid development of traffic engineering in cold regions and its consequent problems need to be considered.In this paper,the dynamic response characteristics of the tunnel portal section in cold regions with harmonic load acting on the lining were studied in the frequency domain.The lining is in close contact with the frozen soil,and there is relative movement between the frozen and unfrozen soil due to the phase change.The analytical solution of the vibration of tunnel portal section caused by the harmonic load acting on the lining was derived under the consideration of the anisotropy frost heave of overlying soil.Based on the continuity conditions and boundary conditions,the undetermined coefficients were obtained,and the analytical solutions for different medium displacements and stresses of the cold-region tunnel system were acquired.The vertical pressure coefficient was equivalently simplified as a variable that could be used to replace the thickness of the overlying soil above the tunnel.The analysis of the parameter model shows that the change of the medium parameters(lining,frozen,and unfrozen soil)affects the circumferential stresses,the radial displacements and their peak frequencies of the soil.For example,the increase of density ratio of tunnel lining to frozen soil decreases the radial stresses of the frozen and unfrozen soil;the increase of volumetric frost heaving strain of the frozen soil increases the radial displacements of the frozen surface and decreases the stability of the frozen surface;the increasing of thickness of the frozen soil significantly reduces the radial displacement of unfrozen soil at dimensionless radius η=4.5 compared with that of frozen soil at η=1.5. 展开更多
关键词 Frost heave Tunnel portal section Relative movement dynamic response characteristics Cold region
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Dynamic physical characteristics of DC arc on arcing horn for HVDC grounding electrode line
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作者 刘益岑 杨晨光 +4 位作者 郭裕钧 张血琴 肖嵩 高国强 吴广宁 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第1期80-87,共8页
The dynamic physical characteristics of a DC arc on an arcing horn for a high voltage direct current(HVDC)grounding electrode line are significantly different from those of the switching device arc,secondary arc,AC fa... The dynamic physical characteristics of a DC arc on an arcing horn for a high voltage direct current(HVDC)grounding electrode line are significantly different from those of the switching device arc,secondary arc,AC fault arc and pantograph-catenary arc.In this work,an experimental platform for the DC arc on the arcing horn was built,and mechanisms of the arc column short circuit and arc root movement were studied.This work further analyzes the characteristics and mechanisms of the arc motion when wind speed and direction,magnetic field and the expansion angle of the electrode are varied.Arc root movement is more likely to occur at the upper electrode.There is a competitive relationship between arc expansion and the transferring effect.The effect of wind on the arc column is greater than the effect on the arc root.The magnetic field has a significant driving effect on both the arc column and the arc root.The research results provide a comprehensive experimental basis for forther probing the method of DC arc suppression,and the improvement of the arcing horn. 展开更多
关键词 grounding electrode line arcing horn DC arc dynamic physical characteristics
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Research on dynamic characteristics of arc under electrode relative motion
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作者 董克亮 吴广宁 +5 位作者 钱鹏宇 许之磊 马亚光 杨泽锋 高国强 魏文赋 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第4期128-137,共10页
The relative motion of the electrodes is a typical feature of sliding electrical contact systems.The system fault caused by the arc is the key problem that restricts the service life of the sliding electrical contact ... The relative motion of the electrodes is a typical feature of sliding electrical contact systems.The system fault caused by the arc is the key problem that restricts the service life of the sliding electrical contact system.In this paper,an arcing experimental platform that can accurately control the relative speed and distance of electrodes is built,and the influence of different electrode speeds and electrode distances on arc motion characteristics is explored.It is found that there are three different modes of arc root motion:single arc root motion mode,single and double arc roots alternating motion mode,and multiple arc roots motion mode.The physical process and influence mechanism of different arc root motion modes are further studied,and the corresponding relationship between arc root motion modes and electrode speed is revealed.In addition,to further explore the distribution characteristics of arc temperature and its influencing factors,an arc magnetohydrodynamic model under the relative motion of electrodes is established,and the variation law of arc temperature under the effect of different electrode speeds and electrode distances is summarized.Finally,the influence mechanism of electrode speed and electrode distance on arc temperature,arc root distance,and arc root speed is clarified.The research results enrich the research system of arc dynamic characteristics in the field of sliding electrical contact,and provide theoretical support for restraining arc erosion and improving the service life of the sliding electrical contact system. 展开更多
关键词 sliding electric contact arc dynamic characteristics electrode relative motion arc root movement
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Review on Dynamic Modeling and Vibration Characteristics of Rotating Cracked Blades
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作者 Hui Ma Zhiyuan Wu +4 位作者 Jin Zeng Weiwei Wang Hongji Wang Hong Guan Wenming Zhang 《Journal of Dynamics, Monitoring and Diagnostics》 2023年第4期207-227,共21页
As one of the most important parts in the engine,the structure and state of the rotating blade directly affect the normal performance of the aeroengine.In order to monitor engine crack failure and ensure flight safety... As one of the most important parts in the engine,the structure and state of the rotating blade directly affect the normal performance of the aeroengine.In order to monitor engine crack failure and ensure flight safety,it is necessary to carry out research on the dynamic modeling of the cracked blade and breathing crack-induced vibration mechanisms.This paper summarizes the current research status on the dynamics of cracked blade,and the related topics mainly include four aspects:crack propagation path,mechanical model of open and breathing cracks,dynamic modeling methods of cracked blades such as lumped mass model,semi-analytical model and finite element model,and dynamic characteristics of cracked blades.The review will provide valuable references for future studies on dynamics and fault diagnosis of cracked blade in aeroengine. 展开更多
关键词 breathing crack crack propagation cracked blade dynamic characteristics dynamic modeling
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Theoretical Analysis and Numerical Simulation of the Static and Dynamic Characteristics of Hydrostatic Guides Based on Progressive Mengen Flow Controller 被引量:13
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作者 GAO Dianrong ZHENG Dan ZHANG Zuochao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第6期709-716,共8页
The oil film thickness of oil hydrostatic guide with constant pressure supply based on capillary restrictor is greatly affected by load, and this kind of hydrostatic guide is usually applied to the machine tools with ... The oil film thickness of oil hydrostatic guide with constant pressure supply based on capillary restrictor is greatly affected by load, and this kind of hydrostatic guide is usually applied to the machine tools with moderate load. The static and dynamic characteristics of the guide have been studied by using some theoretical, numerical and experimental approaches, and some methods and measures have been proposed to improve its performances. The hydrostatic guide based on progressive mengen(PM) flow controller is especially suitable for the heavy numerical control(NC) machine tools. However, few literatures about the research on the static and dynamic characteristics of the hydrostatic guides based on PM flow controller are reported. In this paper, the formulae are derived for analyzing the static and dynamic characteristics of hydrostatic guides with rectangle pockets and PM flow controller according to the theory of hydrostatic bearing. On the basis of the analysis of hydrostatic bearing with circular pocket, some equations are derived for solving the static pressure, volume pressure and squeezing pressure which influence the dynamic characteristics of hydrostatic guides with rectangle pocket. The function and the influencing factors of three pressures are clarified. The formulae of amplitude-frequency characteristics and dynamic stiffness of the hydrostatic guide system are derived. With the help of software MATLAB, programs are coded with C++ language to simulate numerically the static and dynamic characteristics of the hydrostatic guide based on PM flow controller. The simulation results indicate that the sensitive oil volume between the outlet of the PM flow controller and the guide pocket has the greatest influence on the characteristics of the guide, and it should be reduced as small as possible when the field working condition is met. Choosing the oil with a greater viscosity is also helpful in improving the dynamic performance of hydrostatic guides. The research work has instructing significance for analyzing and designing the guide with PM flow controller. 展开更多
关键词 PM flow controller rectangle pocket static characteristics dynamic characteristics hydrostatic guides
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Nonlinear Static and Dynamic Stiffness Characteristics of Support Hydraulic System of TBM 被引量:5
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作者 Jianfeng Tao Junbo Lei +1 位作者 Chengliang Liu Wei Yuan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2019年第6期26-34,共9页
Full-face hard rock tunnel boring machines(TBM)are essential equipment in highway and railway tunnel engineering construction.During the tunneling process,TBM have serious vibrations,which can damage some of its key c... Full-face hard rock tunnel boring machines(TBM)are essential equipment in highway and railway tunnel engineering construction.During the tunneling process,TBM have serious vibrations,which can damage some of its key components.The support system,an important part of TBM,is one path through which vibrational energy from the cutter head is transmitted.To reduce the vibration of support systems of TBM during the excavation process,based on the structural features of the support hydraulic system,a nonlinear dynamical model of support hydraulic systems of TBM is established.The influences of the component structure parameters and operating conditions parameters on the stiffness characteristics of the support hydraulic system are analyzed.The analysis results indicate that the static stiffness of the support hydraulic system consists of an increase stage,stable stage and decrease stage.The static stiffness value increases with an increase in the clearances.The pre-compression length of the spring in the relief valve a ects the range of the stable stage of the static stiffness,and it does not a ect the static stiffness value.The dynamic stiffness of the support hydraulic system consists of a U-shape and reverse U-shape.The bottom value of the U-shape increases with the amplitude and frequency of the external force acting on the cylinder body,however,the top value of the reverse U-shape remains constant.This study instructs how to design the support hydraulic system of TBM. 展开更多
关键词 Tunnel boring machine Support hydraulic system Nonlinear model static stiffness characteristics dynamic stiffness characteristics
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A Study on the Dynamic Characteristics of the Damping Capillary Type Spherical Hydrostatic Bearing 被引量:2
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作者 陈卓如 潘社卫 +1 位作者 张守礼 金朝铭 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1995年第2期24-27,共4页
AStudyontheDynamicCharacteristicsoftheDampingCapillaryTypeSphericalHydrostaticBearingCHENZhuoru;PANShewei;ZH... AStudyontheDynamicCharacteristicsoftheDampingCapillaryTypeSphericalHydrostaticBearingCHENZhuoru;PANShewei;ZHANGShouli;JINChao... 展开更多
关键词 ss:Damping CAPILLARY type SPHERICAL HYDROstatic BEARING dynamic characteristics HYDROstatic stiffness
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