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Applied Mathematics and Mechanics(English Edition) 2022年第2期43卷 203-218页

作者： Shunzu ZHANG Qianqian HU Wenjuan ZHAO School of Civil and Hydraulic Engineering Ningxia UniversityYinchuan750021China

This paper presents a theoretical model for the size-dependent band structure of magneto-elastic phononic crystal(PC)nanoplates according to the Kirchhoff plate theory and Gurtin-Murdoch theory,in which the surface effect and magneto-elastic coupling are considered.By introducing the nonlinear coupling constitutive relation of magnetostrictive materials,Terfenol-D/epoxy PC nanoplates are carried out as an example to investigate the dependence of the band structure on the surface effect,magnetic field,pre-stress,and geometric parameters.The results show that the surface effect has promotive influence on dispersion curves of the band structure,and the band gaps can be improved gradually with the increase in the material intrinsic length.Meanwhile,the band gaps exhibit obvious nonlinear coupling characteristics owing to the competition between the magnetic field and the pre-stress.By considering the surface effect and magneto-elastic coupling,the open and closed points of band gaps are found when the lattice constant to thickness ratio increases.The study may provide a method for flexible tunability of elastic wave propagation in magneto-elastic PC nanoplates and functional design of highperformance nanoplate-based devices.

关键词： magneto-elastic phononic crystal nanoplate surface effect magnetic field band gap

The Dry Cracking of Cementitious Materials in the Eccentric Ring Test and the Concentric Ring Test

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Journal of Wuhan University of Technology(Materials Science) 2022年第2期37卷 212-221页

作者：田聪 ZHENG Zhishan 魏小胜 School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430072China

In order to reduce the randomness of the occurrence of cracks and shorten the long cracking time in the traditional concentric ring tests,the elliptical ring test,the square-eccentric ring test,and the eccentric ring test have been gradually developed.In this paper,we reported experiments on the eccentric ring test and concentric ring test that were carried out to compare the differences between the two methods.It is found that an increase in the water-cement ratio and the amount of aggregate will increase the cracking time.However,a more obvious cracking tendency of cement-based materials can be seen in the eccentric ring test.The correlation between humidity and strain was established by the use of the Kelvin equation and the Laplace equation so that the coupling analysis of humidity and strain during the drying process of cement-based materials could be determined.The experimental results show that the external surface humidity will decrease rapidly in the early stage of drying,while the interior areas of the cement-based materials decrease more slowly.The closer to the inner circle will decrease the humidity slowly.

关键词： the eccentric ring test the concentric ring test crack humidity strain

Nonlinear dynamic analysis of cantilevered piezoelectric energy harvesters under simultaneous parametric and external excitations

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Acta Mechanica Sinica 2018年第3期34卷 561-577页

作者： Fei Fang Guanghui Xia Jianguo Wang School of Civil and Hydraulic Engineering Hefei University of Technology

The nonlinear dynamics of cantilevered piezoelectric beams is investigated under simultaneous parametric and external excitations. The beam is composed of a substrate and two piezoelectric layers and assumed as an Euler-Bernoulli model with inextensible deformation. A nonlinear distributed parameter model of cantilevered piezoelectric energy harvesters is proposed using the generalized Hamilton＇s principle. The proposed model includes geometric and inertia nonlinearity, but neglects the material nonlinearity. Using the Galerkin decomposition method and harmonic balance method, analytical expressions of the frequency-response curves are presented when the first bending mode of the beam plays a dominant role. Using these expressions, we investigate the effects of the damping, load resistance, electromechanical coupling, and excitation amplitude on the frequency-response curves. We also study the difference between the nonlinear lumped-parameter and distributed- parameter model for predicting the performance of the energy harvesting system. Only in the case of parametric excitation, we demonstrate that the energy harvesting system has an initiation excitation threshold below which no energy can be harvested. We also illustrate that the damping and load resistance affect the initiation excitation threshold.

关键词： Parametric and external excitations Nonlinear distributed parameter model Nonlinear dynamic response Energy harvesting Harmonic balance method

Structural performance of a façade precast concrete sandwich panel enabled by a bar-type basalt fiber-reinforced polymer connector

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Frontiers of Structural and civil engineering 2023年第1期17卷 122-137页

作者： Junqi HUANG Qing JIANG Xun CHONG Xianguo YE Caihua LIU School of Civil and Hydraulic Engineering Hefei University of TechnologyHefei 230009China Anhui civil engineering Structures and Materials Laboratory Hefei 230009China

In this study,a novel diagonally inserted bar-type basalt fiber reinforced polymer(BFRP)connector was proposed,aiming to achieve both construction convenience and partially composite behavior in precast concrete sandwich panels(PCSPs).First,pull-out tests were conducted to evaluate the anchoring performance of the connector in concrete after exposure to different temperatures.Thereafter,direct shear tests were conducted to investigate the shear performance of the connector.After the test on the individual performance of the connector,five façade PCSP specimens with the bar-type BFRP connector were fabricated,and the out-of-plane flexural performance was tested under a uniformly distributed load.The investigating parameters included the panel length,opening condition,and boundary condition.The results obtained in this study primarily indicated that 1)the bar-type BFRP connector can achieve a reliable anchorage system in concrete;2)the bar-type BFRP connector can offer sufficient stiffness and capacity to achieve a partially composite PCSP;3)the boundary condition of the panel considerably influenced the out-of-plane flexural performance and composite action of the investigated façade PCSP.

关键词： precast concrete sandwich panel basalt fiber reinforced polymer pull-out performance shear performance out-of-plane flexural performance

Sparse Modal Decomposition Method Addressing Underdetermined Vortex-Induced Vibration Reconstruction Problem for Marine Risers

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China Ocean engineering 2024年第2期38卷 285-296页

作者： DU Zun-feng ZHU Hai-ming YU Jian-xing State Key Laboratory of hydraulic engineering Intelligent Construction and Operation School of Civil EngineeringTianjin UniversityTianjin 300350China

When investigating the vortex-induced vibration(VIV)of marine risers,extrapolating the dynamic response on the entire length based on limited sensor measurements is a crucial step in both laboratory experiments and fatigue monitoring of real risers.The problem is conventionally solved using the modal decomposition method,based on the principle that the response can be approximated by a weighted sum of limited vibration modes.However,the method is not valid when the problem is underdetermined,i.e.,the number of unknown mode weights is more than the number of known measurements.This study proposed a sparse modal decomposition method based on the compressed sensing theory and the Compressive Sampling Matching Pursuit(Co Sa MP)algorithm,exploiting the sparsity of VIV in the modal space.In the validation study based on high-order VIV experiment data,the proposed method successfully reconstructed the response using only seven acceleration measurements when the conventional methods failed.A primary advantage of the proposed method is that it offers a completely data-driven approach for the underdetermined VIV reconstruction problem,which is more favorable than existing model-dependent solutions for many practical applications such as riser structural health monitoring.

关键词： motion reconstruction vortex-induced vibration(VIV) marine riser modal decomposition method compressed sensing

Aeration performances and air—Water mass transfer on steep stepped weirs with horizontal and inclined steps

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Journal of Hydrodynamics 2022年第5期34卷 904-916页

作者： Yvan Arosquipa Nina Rui Shi Davide Wüthrich Hubert Chanson The University of Queensland School of Civil EngineeringBrisbaneAustralia Department of hydraulic engineering Delft University of TechnologyDelftThe Netherlands

At hydraulic structures,some strong interactions may develop between fast flowing waters and the air adjacent to the water in motion that enhance the air-water transfer of atmospheric and volatile gases in the flow.In turn,in-stream structures may contribute to the aeration and re-oxygenation during overflow.The present study aims to characterize the aeration performance of a steep stepped weir,based upon a detailed physical investigation of air-water interfacial properties across a relatively wide range of discharges.The data showed a strong fragmentation of the air-water flows,a very broad range of entrained bubbles and drops,and a large amount of particle clustering.The results implied a monotonic increase in re-aeration with increasing rate of energy dissipation,while the largest aeration efficiency was observed on the horizontal step weir chute,with the smallest on the 1V:2.33H inclined downward steps.Altogether,the study showed that a steep stepped chute can make a sizeable contribution to the re-oxygenation of the waters,although the downward inclined steps reduce the re-aeration performances.

关键词： Stepped weirs aeration re-oxygenation physical modeling flow fragmentation

Simulation of Cement Hydration and Porous Structures by the Hydration-Pixel Probability Model

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Journal of Wuhan University of Technology(Materials Science) 2023年第5期38卷 1044-1055页

作者： TIAN Cong WEI Xiaosheng school of civil engineering Architecture&The EnvironmentHubei University of TechnologyWuhan 430072China School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430072China

This research proposes a new pixel-based model called the hydration-pixel probability model which aims to simplify cement hydration as a probability problem.The hydration capacity of cement,the solution within pores,and the difiusion of solid particles are represented by three probability functions derived from experimental data obtained through electrical resistivity and hydration heat measurements.The principle of the model is relatively simple,and the parameters have clear physical meanings.In this research,the porous structures of difierent cement pastes with w/c ratios of 0.3,0.4,and 0.5 are investigated.The results indicate that the porosity of the cement paste decreases during the first few hours,followed by a rapid decline,and eventually reaches a steady state.The porosity of the paste decreases as w/c ratio decreases,and the rate of decrease is more rapid in the early stages.Referring to the porosity curves,the average degree of hydration and depth of hydration can be derived.The simulation results show that the hydration degree of paste composed of irregular particles is higher than that of the paste composed of round particles.The trend in the development of the average hydration depth is similar to that of the average hydration degree.Upon analyzing the average growth rate of the hydration depth,it is observed that there are two peaks in the curves,which correspond to the three characteristic points in the electrical resistivity test.

关键词： cement hydration model porosity hydration degree simulation

A zero-flux principle for extracting secondary flows in arbitrary vertical planes of naturalrivers

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Journal of Hydrodynamics 2022年第4期34卷 744-755页

作者： De-chao Hu Department of hydraulic engineering Yangtze River Scientific Research InstituteWuhan 430010China School of Civil and Hydraulic Engineering Huazhong Univ.of Science and TechnologyWuhan 430074China

The cross-sectional transverse flow field(represented by u_(con),)of rivers comprises a convective part(represented by ucon)and a circulatory part(represented by ueire),and a zero-flux principle of the ucire has been known for a long time.However,it is still difficult to separate the circulatory part from the convective part quantitatively in a 3-D velocity field,for an arbitrarily vertical plane in natura ivers of iregular shape this study,a ero-flux prineiple of the uis derived,o replace th old zero-fux principle of the ueire:.Based on the new principle,an all-purpose new method is proposed for extracting the circulations in arbitrary vertical planes of natural rivers of irregular shape.The calculation with the new method requires only the distribution of the horizontal velocities of a single vertical line(VL),and is simple.The calculation can be made based on either the velocity field simulated by a 3-D hydrodynamic model or the field measurements obtained by the acacoustic Doppler velocimetry(ADV).The new method is validated by using the field data of the lower Yangtze River.The extracted circulations are reasonable,while the results of the circulation extraction,respectively,based on the velocity field of a 3-D model and the field measurements of the ADV,are shown to be consistent.The capability of the method is also demonstrated,using the typical riverbends of the Yangtze River as examples.

关键词： Real river cross-sectional secondary flow circulation extraction zero-flux principle

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含固支端梁的弹性力学解（英文）

Journal of Zhejiang University-Science A(Applied Physics & engineering) 2015年第10期16卷 805-819页

作者： Chun-xiao ZHAN Yi-hua LIU School of Civil and Hydraulic Engineering Hefei University of Technology

目的:在用应力函数法求含固支端梁的应力和位移时,对固支端只能采用简化的固支边界条件。为此,拟提出一种更好的简化固支边界条件。创新点:在已有固支边界条件的基础上,提出新的固支边界条件,由此得到的含固支端梁的弹性力学解的精度有... 详细信息

目的:在用应力函数法求含固支端梁的应力和位移时,对固支端只能采用简化的固支边界条件。为此,拟提出一种更好的简化固支边界条件。创新点:在已有固支边界条件的基础上,提出新的固支边界条件,由此得到的含固支端梁的弹性力学解的精度有很大提高。方法:1.综合Timoshenko和Goodier提出的两种固支边界条件,构造出一种新的固支边界条件,并应用Airy应力函数法推导出三种含固支端梁的解析解;2.对由不同固支边界条件得到的解析解与有限元解进行比较。结论:1.与已有的固支边界条件相比,本文提出的固支边界条件更佳,尤其是对短梁;2.理论与数值结果均表明,对超静定短梁,位移u不再保持线性分布,经典梁理论中的平截面假设不再适用。

关键词：梁固支端边界条件平面应力弹性力学解

Simulation of ice accumulation around bridge piers during river breakup periods using a discrete element model

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Journal of Hydrodynamics 2022年第1期34卷 94-105页

作者： Tie-jie Cheng Jun Wang Pang-pang Chen Jueyi Sui School of Civil and Hydraulic Engineering Hefei University of TechnologyHefei230009China school of engineering University of Northern British ColumbiaPrince GeorgeBCCanada

During river breakup periods in winter or early spring, a large amount of ice floes of various sizes will be transported by flowing water. The presence of bridge piers in water alters velocity field. As a consequence, the transport process of ice floes around bridge piers will be influenced. It often causes the ice floe congestion around bridge piers. In the present study, the influences of the ice floe size and coverage ratio of ice floating on water surface on ice floe congestion have been examined. The influence of bridge pier layout on ice jam development has been assessed. Results showed that during river breakup period, the ice floe transport capacity around bridge pier decreased. With the presence of bridge piers, the critical coverage ratio of ice floating on water surface for the ice floe congestion depends on the ratio of the side length of ice floe to the pier spacing distance (a / Ln) and ice floe-length Froude number associated with the ice floe length (Fra). A discrete element model (DEM) has been developed to simulate the ice floe accumulating process around bridge piers. Simulation results agree well with those of experiments.

关键词： Bridge pier coverage ratio of floating ice discrete element model ice jam river breakup