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Nonlinear dynamics of a circular curved cantilevered pipe conveying pulsating fluid based on the geometrically exact model

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Applied Mathematics and mechanics(English Edition) 2024年第2期45卷 261-276页

作者： Runqing CAO Zilong GUO Wei CHEN Huliang DAI Lin WANG Department of engineering {1. School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for engineering Structural Analysis and Safety Assessment Wuhan 430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Due to the novel applications of flexible pipes conveying fluid in the field of soft robotics and biomedicine,the investigations on the mechanical responses of the pipes have attracted considerable *** fluid-structure interaction(FSI)between the pipe with a curved shape and the time-varying internal fluid flow brings a great challenge to the revelation of the dynamical behaviors of flexible pipes,especially when the pipe is highly flexible and usually undergoes large *** this work,the geometrically exact model(GEM)for a curved cantilevered pipe conveying pulsating fluid is developed based on the extended Hamilton's *** stability of the curved pipe with three different subtended angles is examined with the consideration of steady fluid *** attention is concentrated on the large-deformation resonance of circular pipes conveying pulsating fluid,which is often encountered in practical *** constructing bifurcation diagrams,oscillating shapes,phase portraits,time traces,and Poincarémaps,the dynamic responses of the curved pipe under various system parameters are *** mean flow velocity of the pulsating fluid is chosen to be either subcritical or *** numerical results show that the curved pipe conveying pulsating fluid can exhibit rich dynamical behaviors,including periodic and quasi-periodic *** is also found that the preferred instability type of a cantilevered curved pipe conveying steady fluid is mainly in the flutter of the second *** a moderate value of the mass ratio,however,a third-mode flutter may occur,which is quite different from that of a straight pipe system.

关键词： curved pipe conveying fluid pulsating fluid geometrically exact model(GEM) nonlinear dynamics parametric vibration flutter

Evaluation on cutting performance of novel PDC cutter for pipe jacking machine

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Underground Space 2024年第1期14卷 34-52页

作者： Long-Chuan Deng Yi-Xiang Yuan Xiao-Zhao Li Qian-Wei Zhuang Chi Zhang Yi-Wei Chen school of Earth Sciences and {1. Nanjing UniversityNanjingJiangsu 210023China Shanghai Tunnel engineering Co.Ltd. Shanghai 200232China State Key Laboratory for Geomechanics and Deep Underground {1. China University of Mining and TechnologyXuzhouJiangsu 221116China school of {1. and engineering Science Shanghai UniversityShanghai 200444China

It is inevitable to cut reinforced concrete(RC)appeared in cross passage of city metro by cutting tools when constructing in densely populated *** previous cutters employed to cut RC are insufficient and easily damaged,so a new polycrystalline diamond compact(PDC)cutter is used to solve this *** on the theoretical analysis of cutting mechanism,both circular and tapered PDC cutters with cutting edge angle of 90and negative front rack angle of 1.are used to cut *** peeling and breaking patterns of cutting concrete are proposed,the nodular and grainy chips are the preferred modes in cutting steel *** LS-DYNA is employed to investigate the cutting performance in *** simulation results show that the average and peak cutting forces increase with the growth of penetration depth,cutting speed,and roundness,and subsequently the recommended penetration depth less than 1.2 mm is obtained to cut RC due to the existence of steel ***,the linear cutting platform is adopted to investigate the force ability and damage state of PDC *** is concluded that the cutting force increases abruptly and fluctuates heavily when cutting the coarse *** patterns occurred in both numerical and experimental results are generally ***,the steel bar is pulled out and the PDC cutter is damaged at the penetration depth of 0.8 mm,while a good cut occurs at the penetration depth of 0.3 *** tapered PDC cutter with a relatively low cutting force is prone to be broken compared with circular PDC *** is suggested that the circular PDC cutter at the penetration depth of 0.3 mm should be used to cut RC in practical engineering.

关键词： PDC cutter RC Pipe jacking machine Linear cutting tests Damage and wear LS-DYNA

Consolidation of high replacement ratio stone column-reinforced ground:Analytical solutions incorporating clogging effect

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Journal of Rock mechanics and Geotechnical {1. 2024年第8期16卷 3311-3326页

作者： Jinxin Sun Mengmeng Lu Baolong Xu Jie Shan school of {1. and Civil engineering China University of Mining and TechnologyXuzhou221116China Key Laboratory for Geomechanics and Deep Underground {1. China University of Mining and TechnologyXuzhou221006China

The utilization of stone columns has emerged as a popular ground improvement strategy,whereas the drainage performance can be adversely hampered by clogging *** the ample progress of calculation methods for the consolidation of stone column-improved ground,theoretical investigations into the clogging effect have not been thoroughly ***,it is imperative to involve the column consolidation deformation to mitigate computational error on the consolidation of composite ground with high replacement *** this context,an analytical model accounting for the initial clogging and coupled time and depth-dependent clogging of stone columns is ***,the resulting governing equations and analytical solutions are obtained under a new flow continuity relationship to incorporate column consolidation *** accuracy and reliability of the proposed model are illustrated by degradation analysis and case studies with good ***,the computed results of the current study are juxtaposed against the existing models,and an in-depth assessment of the impacts of several crucial parameters on the consolidation behavior is *** results reveal that ignoring column consolidation deformation leads to an overestimate of the consolidation rate,with maximum error reaching up to 1.%as the replacement ratio ***,the initial clogging also has a significant influence on the consolidation ***,the increment of depth and time-clogging factors a and b will induce a noticeable retardation of the consolidation process,particularly in the later stage.

关键词： Consolidation Composite ground Stone column Clogging effect Ground improvement Analytical model

Bioinspired coacervate-based bioinks for construction of multiscale tissue engineering scaffolds

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Nano Research 2024年第9期17卷 8209-8219页

作者： Zhongwei Guo Shiqiang Zhang Yilin Guo Jingjing Xia Xiao Wu Hao Hu Rongcheng Hu Fangli Huang Qiulei Gao Chun Liu Jingjiang Qiu Wei Sun school of {1. and Safety engineering Zhengzhou UniversityZhengzhou 450001China Department of Mechanical engineering and {1. Tsinghua UniversityBeijing 100084China Precision Medicine Institute Guangdong Provincial Key Laboratory of Orthopedics and TraumatologyThe First Affiliated Hospital of Sun Yat-sen UniversityGuangzhou 510080China Department of Mechanical engineering Drexel UniversityPhiladelphiaPA 19104USA

engineering hydrogels that resemble biological tissues of various lengths via conventional fabrication techniques remains ***-dimensional(3D)bioprinting has emerged as an advanced approach for constructing complex biomimetic 3D architectures,which are currently restricted by the limited number of available bioinks with high printability,biomimicry,biocompatibility,and proper mechanical *** by ubiquitous coacervation phenomena in biology,we present a unique mineral-biopolymer coacervation strategy that enables the hierarchical assembly of nanoclay and recombinant human collagen(RHC).This system was observed to undergo a coacervation transition(liquid‒liquid phase separation)*** formed dense phase separated from its supernatant is the coacervate of clay-RHC-rich complexes,where polymer chains are sandwiched between silicate *** dynamics simulation was first used to verify and explore the coacervation ***,the coacervates were demonstrated to be potential bioinks that exhibited excellent self-supporting and shear-thinning viscoelastic *** extrusion-based printing,the versatility of the bioink was demonstrated by reconstructing the key features of several biological tissues,including multilayered lattice,vascular,nose,and ear-like structures,without the need for precrosslinking operations or support ***,the printed scaffolds were cytocompatible,elicited minimal inflammatory responses,and promoted bone regeneration in calvarial defects.

关键词： bioinks coacervation mineral-biopolymer nanoclay tissue engineering scaffold

Indentation behavior of a semi-infinite piezoelectric semiconductor under a rigid flat-ended cylindrical indenter

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Applied Mathematics and mechanics(English Edition) 2024年第4期45卷 649-662页

作者： Shijing GAO Lele ZHANG Jinxi LIU Guoquan NIE Weiqiu CHEN State Key Laboratory of Mechanical Behavior and System Safety of Traffic engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China school of Mechanical {1. Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Key Laboratory for mechanics of Intelligent Materials and Structures Department of Engineering MechanicsShijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Computer Aided Design and Computer Graphics Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou 310027China

This paper theoretically studies the axisymmetric frictionless indentation of a transversely isotropic piezoelectric semiconductor(PSC)half-space subject to a rigid flatended cylindrical *** contact area and other surface of the PSC half-space are assumed to be electrically *** the Hankel integral transformation,the problem is reduced to the Fredholm integral equation of the second *** equation is solved numerically to obtain the indentation behaviors of the PSC half-space,mainly including the indentation force-depth relation and the electric potential-depth *** results show that the effect of the semiconductor property on the indentation responses is limited within a certain range of variation of the steady carrier *** dependence of indentation behavior on material properties is also analyzed by two different kinds of *** element simulations are conducted to verify the results calculated by the integral equation technique,and good agreement is demonstrated.

关键词： piezoelectric semiconductor(PSC) insulating indenter electromechanical response singular integral equation finite element simulation

Study on a conical bearing for acceleration-sensitive equipment

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Earthquake engineering and engineering Vibration 2024年第1期23卷 103-128页

作者： Pang Hui Xu Wen Dai Junwu Jiang Tao Key Laboratory of Earthquake engineering and engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China school of Civil {1. and Transportation Beihua UniversityJilin 132013China

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during ***,isolation strategies give less attention to acceleration-sensitive systems or ***,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance *** a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system ***,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various *** to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement ***,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

关键词： seismic isolation acceleration-sensitive equipment the conical pendulum bearing shake table tests isolation performance,numerical model

Micropores in G20Mn5N cast steel and their influence on stress distribution

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Journal of Southeast University(English Edition) 2024年第3期40卷 286-294页

作者： Yan Huadong Jin Hui school of Civil {1. Southeast UniversityNanjing 211189China Jiangsu Key Laboratory of engineering {1. Southeast UniversityNanjing 211189China

To accurately analyze the impact of casting pores in steel,high-resolution 3D X-ray tomography technology was used to gather detailed statistical information about *** micropores were classified as gas,shrinkage,and gas-shrinkage pores depending on their formation origin and *** tendencies and affinity parameters were defined to characterize the spatial correlations among these three types of *** 3D data from X-ray tomography scans were then integrated into finite element analysis(FEA)software to predict how micropore shape,size,and distribution influence stress distribution within the *** results show that certain inflection points with small local radii within the cast pores are major contributors to stress ***,cast pores cannot be simply modeled as ideal spherical *** sphericity and volume of pores have a significant impact on the stress concentration of the ***,lower sphericity and larger pore volumes result in higher stress ***,the internal pores of steel castings exhibit specific global distribution *** located on the surface of the specimen lead to significantly higher stress concentrations compared to those located inside the specimen.

关键词： cast steel micropores X-ray tomography 3D reconstruction finite element analysis

Sandwich structures with tapered tubes as core:A quasi-static investigation

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Defence Technology（防务技术） 2024年第3期33卷 447-462页

作者： Xinmei Xiang Dehua Shao Xin Zhang Umer Sharif Ngoc San Ha Li Xiang Jing Zhang Jiang Yi school of Civil {1. Guangzhou UniversityGuangzhouChina Department of mechanics and Aerospace {1. Southern University of Science and TechnologyShenzhenGuangdongChina school of {1. Centre for Innovative Structures and MaterialsRMIT UniversityMelbourneAustralia China Southern Airlines Co. LtdShenzhen BranchShenzhen518000China

In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without *** results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 1..8% higher,respectively,than those of the conical tube ***,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their ***,the tapered corrugated tubes'resistance to oblique impacts was *** to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical *** conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall *** and SEA of DTS with corrugation number of 8 increased by 1..4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 1..

关键词： Sandwich structure Corrugated tube Tapered tube Quasi-static Energy absorption

Study on damage characteristics of iron ore under variable line density charge structure blasting

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Rock Mechanics Bulletin

Rock mechanics Bulletin 2024年第4期3卷 1-14页

作者： Xinmin Ma Yiyin Hu Xinshuo Li Yongsheng Ruan Yuan Jin Wenqing Yang school of {1. and Civil engineering China University of Mining and Technology(Beijing)Beijing100083China

Blasting test research was conducted on iron ore specimens with variable line density charging *** tomography(CT),digital image processing,and three-dimensional model reconstruction techniques were used to analyze the damage characteristics of iron ore specimens after blasting based on the calculated number of box *** results show that increasing the variable line density section charge uncoupling coefficient reduces the overall damage to the specimen by up to 1.73%,indicating that the overall damage size negatively correlates with the size of the variable line density section charge uncoupling *** damage characteristics of iron ore specimens from different layers(uncoupled charging section,transition section,coupled charging section)have some variability;when the uncoupling coefficient of the uncoupled charging section was reduced,the uncoupled section of the center of the damaged layer increased and then *** contrast,the transition section shows a trend of increase,and the coupled section shows a minor difference,fully demonstrating the change in the variable line density section of the uncoupling coefficient of the specimen blasting damage *** study concludes that in the actual blasting project,choosing a reasonable variable line charge density structure can make the release of explosive blast energy more uniform to efficiently and thoroughly use explosive power to improve the iron ore crushing effect.

关键词： Iron ore Blasting Variable line density charges Damage characterization