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analytical study on pretensioned bolt-cable combined support of large cross-section tunnel

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Science China(Technological Sciences) 2020年第9期63卷 1808-1823页

作者： LUO JiWei ZHANG DingLi FANG Qian LI Ao SUN ZhenYu CAO LiQiang Key Laboratory for Urban Underground Engineering of the Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

To study the mechanical responses of large cross-section tunnel reinforced by pretensioned rock bolts and anchor cables, an analytical model is proposed. Considering the interaction between rock mass and bolt-cable support, the strain softening characteristic of rock mass, the elastic-plastic characteristic of bolt-cable support, and the delay effect of installation are considered in the model. To solve the different mechanical cases of tunneling reinforced by bolt-cable support, an analytical approach has been put forward to get the solutions of stress and displacement associated with tunneling. The proposed analytical model is verified by numerical simulation. Moreover, parametric analysis is performed to study the effects of pretension force,cross-section area, length, and supporting density of bolt-cable support on tunnel reinforcement, which can provide references for determining these parameters in tunnel design. Based on the analytical model, a new Ground Response Curve(GRC)considering the reinforcement of bolt-cable support is obtained, which shows the pretension forces and the timely installation are important in bolt-cable support. In addition, the proposed model is applied to the analysis of the Great Wall Station Tunnel, a high-speed railway tunnel with a super large cross-section, which shows that the analytical model of bolt-cable support was a useful tool for preliminary design of large cross-section tunnel.

关键词： bolt-cable combined support analytical model pretension force large cross-section tunnel reinforcement

Three-dimensional temperature prediction in cylindrical turning with large-chamfer insert based on a modified slip-line field approach

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Chinese Journal of Aeronautics 2021年第10期34卷 265-281页

作者： Cheng HU Kejia ZHUANG Yuanwei TANG Jian WENG Xiaoming ZHANG Han DING Hubei Digital Manufacturing Key Laboratory School of Mechanical and Electronic EngineeringWuhan University of TechnologyWuhan 430070China Institute of Advanced Materials and Manufacturing Technology Wuhan University of TechnologyWuhan 430070China AECC Guizhou Liyang Aviation Power CO.LTD Guiyang 550000China State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

Chamfered inserts have found broader applications in metal cutting process especially in high-performance machining of hard-to-cut materials for their excellent edge resistance and cutting toughness.However,excessive heat generation and resulting high cutting temperature eventually cause severe tool wear and poor surface integrity,which simultaneously limits the optimal selection of machining parameters.In the present study,an analytical thermal–mechanical model is proposed for the prediction of the three-dimensional(3-D)temperature field in cylindrical turning with chamfered round insert based on a modified slip-line field approach.First,an innovative discretization method is introduced in a general 3-D coordinate system to provide a comprehensive demonstration of the irregular cutting geometry and heat generation zones.Then,a plasticity-theory-based slip-line field model is developed and employed to determine the intensities and geometries of every elementary heat sources in Primary Deformation Zones(PDZ),Secondary Deformation Zones(SDZ)and Dead Metal Zones(DMZ).At last,a 3-D analytical model is suggested to calculate the temperature increases caused by the entire heat sources and associated images.The maximum cutting temperature region predicted is found existing upon the chip-tool contact area rather than the tool edge.Moreover,the rationalities of cutting parameters employed are analyzed along with theoretical material removal rates and ensuing maximum cutting temperatures.The results indicate that the cutting conditions with large depth of cut and high cutting speed are more desirable than those with high feed rates.The proposed models are respectively verified through a series of 3-D Finite Element(FE)simulations and dry cutting experiments of Inconel 718 with chamfered round insert.Satisfactory agreement has been reached between the predictions and simulations as well as the measurements,which confirms the correctness and effectiveness of the presented analytical model.

关键词： analytical model Chamfered round insert Dead metal zone Prediction of temperature Slip-line field

Experimental and theoretical investigation of the failure behavior of a reinforced concrete target under high-energy penetration

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Acta Mechanica Sinica 2020年第1期36卷 116-129页

作者： Fanlin Meng Tianbao Ma Xiangzhao Xu State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

The dynamic mechanical properties of concrete and reinforced concrete targets subjected to high-speed projectile impact loading have a significant influence on the impact resistance of protective structures.In this study,high-speed projectile penetration and perforation of concrete and reinforced concrete structures was carried out to determine the high-energy impact loading.The failure behaviors of projectile penetration and perforation of the concrete and reinforced concrete targets were investigated,and the destruction characteristics of the targets were measured.An analytical model was established using the principle of minimum potential energy.The results show that the theoretical predictions are consistent with the experimental data,indicating that the energy method is effective for predicting the dynamic mechanical properties of concrete and reinforced concrete targets under high-speed projectile penetration.

关键词： Reinforced concrete Penetration analytical model Failure behavior

Theoretical prediction for effective properties and progressive failure of textile composites:a generalized multi-scale approach

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Acta Mechanica Sinica 2021年第8期37卷 1222-1244,I0001页

作者： Haoyuan Dang Peng Liu Yinxiao Zhang Zhenqiang Zhao Liyong Tong Chao Zhang Yulong Li Department of Aeronautical Structure Engineering Northwestern Polytechnical UniversityXi’an 710072 China 2 Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Applications Xi’an 710072 China 3 Joint International Research Laboratory of Impact Dynamics and Its Engineering Applications Xi’an 710072 China 4 School of Science Harbin Institute of TechnologyShenzhen 518055 China 5 School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneySydneyNSW 2006Australia

A generalized analytical model is developed to predict progressive failure behavior of several types of textile composites,including plain weave composites,twill weave composites,two-dimensional tri-axially braided composites and warpreinforced 2.5-dimensional braided composites.In this model,the unit cell(UC)of composite is firstly identified and reconstructed into a refined lamina structure with multiple equivalent lamina elements(ELEs)based on apt geometrical approximation and assumptions.Secondly,two-way coupled stress-strain responses within the UC(macro-scale)and ELE(meso-scale)are established through a universal series-parallel model(SPM).Finally,a progressive damage model,which consists of damage initiation criteria and a stiffness evolution strategy,is employed to predict damage behavior of the ELE.The analytical results including mechanical properties and progressive failure process are validated against the existing numerical and experimental ones in literature.The validated analytical model is then used to study the effects of global fiber volume fraction,braided angle,shear failure coefficient and selected failure criteria on stiffness,strength and failure process.The present results demonstrate the efficiency and generic capability of the present analytical model for predicting the mechanical responses of a range of textile composites.

关键词： Textile composites analytical model Series-parallel model Damage mechanics Strength

A precise calculation of delayed coincidence selection efficiency and accidental coincidence rate

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Chinese Physics C 2015年第5期39卷 80-85页

作者：余婧懿王喆陈少敏 Department of Engineering Physics Tsinghua University

A precise background evaluation model is coincidence method, which is widely used in reactor proposed to address the complex data structure of the delayed electron-antineutrino oscillation experiments. In this model, effects from the muon veto, uncorrelated random background, and background are all studied analytically, simplifying the estimation of the systematic uncertainties of signal efficiency and accidental background rate. The results of the calculations are validated numerically with a number of simulation studies and also applied and validated in the recent Daya Bay hydrogen-capture based oscillation measurement.

关键词： delayed coincidence accidental coincidence inverse beta decay analytical model

Analysis of vibration reduction level in an 8/6 switched reluctance machine by active vibration cancellation

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第10期11卷 808-816页

作者： Xu LIU Zai-ping PAN Z. Q. ZHU School of Electrical Engineering Zhejiang University Hangzhou 310027 China Department of Electronic and Electrwal Engmeermg University of Sheffield Sheffield S1 3JD UK

This paper proposes an analytical model for predicting the maximum vibration reduction level in a four-phase 8/6 switched reluctance machine(SRM) by employing active vibration cancellation(AVC),one of the most effective and convenient methods for reducing the vibration and acoustic noise produced by SRMs.Based on the proposed method,the factors that influence the vibration reduction level are analyzed in detail.The relationships between vibration and noise reduction levels at resonance frequency and rotor speed are presented.Moreover,it is shown that a large damping factor will lead to smaller vibration reduction level with AVC while,in contrast,a large resonance frequency will increase the vibration reduction level.Both finite element analyses and experiments were carried out on a prototype 8/6 SRM to validate the proposed method.

关键词： Active vibration cancellation analytical model Switched reluctance machine Vibration

A Novel Handoff Algorithm for Hierarchical Cellular Networks

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China Communications 2016年第8期13卷 136-147页

作者： Xiaorong Zhu Mengrong Li Wenchao Xia Hongbo Zhu Nanjing University of Posts and Telecommunications Nanjing China National Mobile Communications Research Laboratory Southeast University Nanjing China

In this paper, we propose a novel speed and service-sensitive handoff algorithm and analytical model for hierarchical cellular networks.First, we use the Gauss-Markov mobility model to predict the speeds of mobile stations, and divide mobile stations into three classes based on the predicted speeds: fast, medium-speed, and slow.Then, according to the mobility classification,network conditions, and service types, mobile stations will be handoff to the proper target networks prior to the deterioration of the currently operating channel. We further develop an analytical model to evaluate the performance of such a hierarchical system with different speed classes and service types. Simulations and analytical results show that the proposed handoff algorithm can significantly improve the network performance in terms of the handoff failure probability, unnecessary handoff probability, and network throughput, comparing with the traditional algorithms.

关键词： Hierarchical cellular networks handoff algorithm Gauss-Markov mobility model analytical model

analytical and Numerical modelling of FRP Debonding from Concrete Substrate under Pure Shearing

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Journal of Wuhan University of Technology(Materials Science) 2012年第1期27卷 142-148页

作者：潘金龙 XU Zhun C K Y Leung LI Zongjin Key Laboratory of Concrete and Pre-stressed Concrete Structures of Ministry of Education Southeast UniversityNanjing 210096 Dept.of Civil and Environmental Engineering Hong Kong University of Science and TechnologyHongKongChina

External bonding of fiber reinforced polymer （FRP） composites on the concrete structures has been proved to be an effective and efficient way to strengthen concrete structures. For a FRP strengthened concrete beam, it is usually observed that the failure occurs in the concrete and a thin layer of concrete is attached on the surface of the debonded FRP plate. To study the debond behavior between concrete and FRP composites, an analytical model based on the three-parameter model is developed to study the debonding behavior for the FRP-to-concrete joint under pure shearing. Then, nonlinear FEM analysis is conducted to verify the PrOposed analytical model. The FEM results shows good agreement with the results from the model. Finally, with the analytical model, sensitivity analyses are performed to study the effect of the interracial parameters or the ~eometric parameters on the debondin~ behavior.

关键词： FRP composites debonding behavior analytical model nonlinear FEM analysis

Real-time,decentralized and bio-inspired topology control for holonomic autonomous vehicles

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International Journal of Intelligent Computing and Cybernetics 2012年第3期5卷 359-380页

作者： Cem Safak Sahin M.Ümit Uyar Advanced Information Technologies BAE SystemsBurlingtonMassachusettsUSA Department of Electrical Engineering The City College of The City University of New YorkNew YorkUSA

Purpose–This paper aims to present an approach for a bio-inspired decentralization topology control mechanism,called force-based genetic algorithm(FGA),where a genetic algorithm(GA)is run by each holonomic autonomous vehicle(HAV)in a mobile ad hoc network(MANET)as software agent to achieve a uniform spread of HAVs and to provide a fully connected network over an unknown geographical terrain.An HAV runs its own FGA to decide its next movement direction and speed based on local neighborhood information,such as obstacles and the number of neighbors,without a centralized control unit or global knowledge.Design/methodology/approach-The objective function used in FGA is inspired by the equilibrium of the molecules in physics where each molecule tries to be in the balanced position to spend minimum energy to maintain its position.In this approach,a virtual force is assumed to be applied by the neighboring HAVs to a given HAV.At equilibrium,the aggregate virtual force applied to an HAV by its neighbors should sum up to zero.If the aggregate virtual force is not zero,it is used as a fitness value for the HAV.The value of this virtual force depends on the number of neighbors within the communication range of Rcom and the distance among them.Each chromosome in our GA-based framework is composed of speed and movement direction.The FGA is independently run by each HAV as a topology control mechanism and only utilizes information from neighbors and local terrain to make movement and speed decisions to converge towards a uniform distribution of HAVs.The authors developed an analytical model,simulation software and several testbeds to study the convergence properties of the FGA.Findings-The paper finds that coverage-centric,bio-inspired,mobile node deployment algorithm ensures effective sensing coverage for each mobile node after initial deployment.The FGA is also an energy-aware self-organization framework since it reduces energy consumption by eliminating unnecessary excessive movements.Fault-tolerance is another important fea

关键词： Genetic algorithms Spatial node distribution Mobile ad hoc networks Topology control Bio-inspired algorithm analytical model Mobile networks