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Study on interfacial mechanical properties of bonded pipe joint under dynamic load

HELIYON 2024年第16期10卷 e36369页

作者： Lin, Zhenhao Li, Shanqing Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510623 Peoples R China

This study analyses the interfacial mechanical behaviour of adhesive-bonded pipe joints under dynamic loading conditions. First, a mechanical model of the bonding interface of a pipe joint was established. Next, computational formula for the interfacial slip and shear stress in the pipe joints were obtained using variable separation, eigenfunction expansion, and Laplace transform methodologies. Further, the effects of various parameters, including the loading duration, bond length, adhesive layer thickness, stress rate, adhesive shear modulus, elastic moduli of the main pipe and coupler pipe, and adhesive-layer thickness, on the mechanical response of the pipe joints were assessed. The goal is to study the impact of these parameters on the maximum shear stress, interfacial slip, and normal stress in the main and coupler pipes, their effects on the pipe joint strength can be determined, thereby providing a theoretical basis for the design of practical pipe-joint configurations. The innovation of this study is as follows: it considers high-stress-rate dynamic loads for formulating complete mathematical equations. Further, it employs theoretical methods to calculate the relative slip and shear stress in pipe joints, through which theoretical formulas for engineering applications of adhesive-bonded pipe joints were derived. Additionally, the study analyses the impact of various parameters on the dynamic mechanical behaviour of the adhesive layer at the pipe joint interface, leading to a deeper understanding of the interface mechanical behaviour characteristics and key parameters to be considered while receiving dynamic loads in pipe joints.

关键词： Bonded joints Dynamic loads Pipe joints Interfacial mechanical properties

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Photo-Activated Snap-Through of Nematic Shallow Spherical Shells

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Acta Mechanica Solida Sinica 2022年第2期35卷 239-247页

作者： Yanli Lin Linghui He Renhuai Liu MOE Key Lab of Disaster and Control in Engineering Institute of Applied MechanicsJinan UniversityGuangzhou 510632China CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of ChinaHefei 230026China

Photo-responsive nematic polymers can transduce light into mechanical work,but the rate is limited by the quasi-static *** enhance the work output,a strat・egy of exploiting photo-triggered snap-through of glassy nematic shallow spherical shells with hemeotropic director alignment is examined *** criterion for the nonlinear instability is derived analytically by using the modified iteration *** is shown that,for thin shells of small height and large basal radius,snap-through can be caused by an incident light with moderate irradiation *** phenomenon may inspire some new designs of contactless and ultra-fast actuation devices with high-rate output of mechanical work.

关键词： Nematic shell Snap-through Ultra-fast actuation

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Three-dimensional exact solutions of double-coated structure with arbitrary thickness under normal point load

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APPLIED MATHEMATICAL MODELLING 2023年第1期117卷 762-785页

作者： Shang, Shouming Hou, Pengfei Li, Qiuhua Zhang, Wenhua Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body Changsha 410082 Peoples R China AV GA Huanan Aircraft Ind Co Ltd Zhuhai 519000 Peoples R China

Explicit closed expressions of stresses and displacements of an adherend and an adhe-sive provide researchers and designers with insight into the effects of variable parameter properties on structural performance. Through potential theory method, the Green's func-tions of a double-coated structure under normal point load are solved using the mirror image method, where the mirror image rule satisfies the recursion law of the Fibonacci sequence. The stress distribution of the multilayer structure under the action of point load is presented in the form of an infinite series with a fast convergence rate. A guideline for the design of coating thickness and material parameters to reduce interfacial stress is de-veloped (reduce adhesive thickness, reduce elastic modulus of adherend, increase elastic modulus of adhesive). The accuracy of the exact solution is demonstrated through com-parison with contact analytical solutions. In addition, the critical load of interface shear delamination failure is predicted. The stresses and displacements of the adherend and the adhesive are presented with the solutions, which can serve as a reference for researchers and designers.(c) 2023 Published by Elsevier Inc.

关键词： Double-coated structures Three-dimensional accurate solution Overall stress field Interface failure Exact solution

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A Novel Regularized Adaptive Matching Pursuit for Moving Force Identification Using Multiple Criteria and Prior Knowledge

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2023年第10期23卷 2350117-2350117页

作者： Xu, Bohao Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Moving force identification (MFI) is one of the challenging tasks in structural health monitoring (SHM) of bridges. As an inverse problem, continuous attention is needed to address the ill-posedness of MFI system matrix, computational efficiency and accuracy. Therefore, a novel regularized adaptive matching pursuit (NRAMP) framework is proposed for MFI using multiple criteria and prior knowledge in this study. Firstly, a relationship between moving forces and structural responses is established. With the utilization of redundant matrix, the MFI problem is converted into one of the sparse recoveries. A new adaptive criterion related to atoms both in the sparse regularization and LSQR factorization is introduced into the regularized orthogonal matching pursuit (ROMP) process. The ill-posedness of system matrix in sparse recovery can be reduced greatly, and the unknown sparsity problem can be skipped. Furthermore, the optimal atoms of redundant matrix will be selected repeatedly based on another criterion related to prior knowledge that the static axle-weight of a vehicle is the main component of moving vehicle force. The residual in each iteration will be saved and the atoms with the smallest residual are chosen at last. Finally, to assess the feasibility of the proposed method, numerical simulations on identification of single moving force with impulse components and two unequal moving forces, and experimental verifications on MFI of a model vehicle moving on a beam in laboratory are also carried out. The results show that the relative percentage errors between the identified and true gross vehicle weight keep under 3.6% in all measured cases, and the executive time of the proposed method is far less than that due to common OMP methods.

关键词： Moving force identification (MFI) structural health monitoring (SHM) redundant concatenated dictionary sparse regularization matching pursuit vehicle-bridge interaction

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Future drought overestimations due to no constraints of CO2 physiological effect and land-atmosphere coupling on potential evapotranspiration

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ENVIRONMENTAL RESEARCH LETTERS 2024年第12期19卷 124031页

作者： An, Xuehua Zhang, Yifang Sun, Shanlei Chai, Rongfan Bi, Zaoying Li, Jinjian Zhou, Yang Zhou, Botao Chen, Haishan Nanjing Univ Informat Sci & Technol Collaborat Innovat Ctr Forecast & Evaluat Meteorol Key Lab Meteorol Disaster Int Joint Res Lab Climate & Environm ChangeMinist Nanjing Peoples R China Zhangzhou Meteorol Bur Zhangzhou Peoples R China China Elect Power Res Inst Renewable Energy Res Ctr Beijing Peoples R China State Key Lab Operat & Control Renewable Energy & Beijing Peoples R China Chengdu Univ Informat Technol Sch Atmospher Sci Plateau Atmosphere & Environm Key Lab Sichuan Prov Chengdu Peoples R China

Various offline drought indices have been widely used to project dryness/wetness and drought changes. However, the results derived from these indices often differ from or even contradict observations and direct projections made by coupled climate models. Therefore, it is crucial to investigate this scientific debate thoroughly and identify the potential causes. This study adopts a water demand-side perspective, focusing on potential evapotranspiration (PET), to address such controversy. Employing the Standardized Precipitation-Evapotranspiration Index (SPEI), three PET models including the Food and Agriculture Organization of the United Nations' report 56 (FAO-56) Penman-Monteith (PM) model, a corrected FAO-56 PM model incorporating CO(2 )physiological effect (PMCO2), and a land-atmosphere coupled PET model (PET-LAC) are further compared. Despite projected increases in PET across most land areas, the PM shows the most pronounced increases among these PET models. Compared to PMCO2 and PET-LAC, the PM model predicts the most significant drying, with the 3-month SPEI decreasing by 0.50 +/- 0.23 yr(-1). Additionally, it projects the most substantial drought intensification, with increases in areas, intensity, and duration of 28 +/- 6.9%, 0.70 +/- 0.20 yr(-1), and 2.90 +/- 0.83 month yr(-1), respectively. Meanwhile, these projections correspond to the most extensive area percentages, with 78.5 +/- 10% for drying, 94.8 +/- 7.2% for drought intensity, and 93.6 +/- 7.9% for drought duration. These findings imply that the commonly used PM model overestimates future drought conditions. Differences and contradictions between the drought projections from PM-based offline indices and direct climate model outputs can be partly attributed to the omission of CO2 physiological effect and land-atmosphere coupling constraints in the PM model. This study highlights the importance of improving PET models by incorporating these constraints, thereby providing valuable insights for enhanci

关键词： offline drought index CO2 physiological effect land-atmosphere coupling constraints potential evapotranspiration standardized precipitation-evapotranspiration index

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Global warming changes patterns of runoff and sediment flux in Tibetan Yangtze River headwater

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JOURNAL OF HYDROLOGY 2025年 656卷

作者： Zhou, Yinjun Han, Junfeng Wang, Feng Liu, Xisheng Liu, Yujiao Yan, Xia Zhang, Guoshuai Ma, Junxiao Wei, Tong Jin, Zhongwu Li, Zhijing Li, Dongfeng Wang, Gang Shi, Lu Lai, Zhongping Changjiang River Sci Res Inst Minist Water Resources Key Lab River Regulat & Flood Control Wuhan 430010 Peoples R China PowerChina Chengdu Engn Corp Ltd Chengdu 610000 Peoples R China Shantou Univ Inst Marine Sci Guangdong Prov Key Lab Marine Disaster Predict & P Shantou 515063 Peoples R China Hydrol Water & Resources Forecast Ctr Qinghai Prov Xining 810000 Qinghai Peoples R China Peking Univ Coll Environm Sci & Engn Key Lab Water & Sediment Sci Minist Educ Beijing 100871 Peoples R China

The Tibetan Plateau acts as an Asian water tower and amplifies global warming, which leads to increased runoff and sediment flux in Tibetan rivers in recent years. Consequently, downstream areas face an increased risk of flood disasters. However, there is still a lack of clarity regarding the alterations, impacts, and mechanisms involved in runoff and sediment flux based on the latest data. Here, the cumulative anomaly, sliding T-test, and M-K trend test were employed to analyze the temporal mutation of meteorological and hydrological data (1957-2023 CE) from Yangtze River headwaters. The analysis revealed three distinct periods: P0 (1957-2004), P1 (2005-2016), and P2 (2017-2023), and demonstrated that (1) the maximum monthly runoff shifted from July (P0-P1) to September (P2) due to increased icemelt;(2) the ratio of September sediment flux to annual increased from 13% (P1) to 20% (P2);and (3) the percentage of temperature contribution to runoff increased from 44% (P1) to 57% (P2), overtaking that of the precipitation. In September the warming-driven increase in runoff overlapped with sediment flux increase caused by reduced sediment fixation capacity of vegetation. Our findings, which reveal that global warming drives both runoff peak shifting from July to September and sediment flux sharp increase in September, are critical for future disaster prevention and siltation control in downstream regions.

关键词： The Yangtze River source region Water and sediment fluxes Global warming Sediment cycle

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An improved block orthogonal matching pursuit for moving force identification using block-sparse compressed sensing

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MEASUREMENT 2023年 222卷

作者： Liang, Yi Hou, Zhilong Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Moving force identification (MFI) based on compressed sensing (CS) has been proven to be promising in bridge structural health monitoring. Nevertheless, there exist the difficulties in storage and transmission cost of massive monitoring data and the lack of considering the block-sparse features of moving forces in particular transform domains. Inspired by the structural characteristics of sparse representation data, a block-sparse compressed sensing (BSCS) framework is first developed to reconstruct moving forces with block-sparse distribution in the frequency domain. To solve the BSCS equation, an improved block orthogonal matching pursuit algorithm, considering atom screening strategy (ASS-BOMP), is then proposed to ensure that moving forces can still be successfully identified even if the preset block length is inconsistent with the block-sparse features of moving forces. The optimal coherence threshold parameters in the atom screening strategy are determined by the Bayesian information criterion (BIC). Finally, the accuracy and feasibility of the proposed method are validated through numerical simulations and laboratory experiments. The results show that the proposed method can effectively compress response data and accurately identify moving forces distributed in the form of frequency band. Furthermore, the ASS-BOMP algorithm outperforms the traditional BOMP with higher MFI accuracy and robustness.

关键词： Moving force identification (MFI) Block orthogonal matching pursuit (BOMP) Compressed sensing (CS) Block-sparse Sparse representation Structural health monitoring (SHM)

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Buckle Propagation in Steel Pipes of Ultra-high Strength:Experiments,Theories and Numerical Simulations

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Acta Mechanica Solida Sinica 2020年第4期33卷 546-563页

作者： Haofeng Liang Jiahui Zhou Jixin Lin Fusong Jin Fei Xia Jianghong Xue Jiachu Xu School of Civil and Construction Engineering Jinan University/Key Lab of Disaster Forecast and Control in EngineeringMinistry of EducationGuangzhou 510632China

In this paper,experimental,theoretical and numerical approaches were employed to scrutinize the buckle propagation events occurring in pipes subjected to external *** groups of samples with different radius-to-thickness ratios were fabricated using steel pipes of ultra-high strength and were subjected to compression of external pressure in a sealed pressure vessel specially designed and customized for the *** results were recorded through a data acquisition *** facilitating the theoretical calculations,uniaxial tensile tests were performed on tensile pieces cut from the same pipes to obtain the material *** was found from the experimental results that once a buckle is initiated in a pipe,the external pressure dropped to a specific value called buckle propagation pressure and kept at this level until the whole pipe is flattened into a dog-bone *** on the measured material properties and geometric parameters,theoretical solutions were computed using established ring models and shell model,and finite element predictions were also obtained from ABAQUS *** efficiency and accuracy of the shell model and finite element model were expounded by comparing various theoretical solutions and numerical predictions with the experimental *** the authenticated shell model and finite element model,a deep insight into the phenomenon of buckle propagation of pressurized long pipes was provided by performing a series of parametric study.

关键词： Steady-state buckle propagation.Ring model Shell model Subsea pipes External pressure

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A highly stretchable and sensitive carboxymethyl chitosan-based hydrogel for flexible strain sensors

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JOURNAL OF MATERIALS CHEMISTRY C 2023年第44期11卷 15720-15730页

作者： Liu, Haote Cao, Lin Wang, Xiao Xu, Congjie Huo, Haoling Jiang, Bixia Yuan, Hong Lin, Zhidan Zhang, Peng Jinan Univ Inst Adv Wear & Corros Resistant & Funct Mat Guangzhou 510632 Peoples R China Jinan Univ Inst Appl Mech MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Guangzhou Inst Sci & Technol Sch Architectural Engn Guangzhou 510540 Peoples R China

It is essential to diagnose Parkinsonism at an early stage to prevent functional impairments in patients and improve their level of healthcare. However, low electrical signal transmission and poor stretchability limit the application of flexible hydrogel sensors in the early diagnosis of Parkinsonism. CGTX-IX composite hydrogels were prepared using carboxymethyl chitosan (CMCS), glyoxal, tannic acid (TA), and ionic liquid ([BMIM][Cl]). The CGTX-I3 composite hydrogel has reversible dynamic chemical bonds, such as imine and hydrogen bonds, and physical interactions. It exhibits good mechanical properties (elongation at break of 112.5% and tensile strength of 284.4 kPa) and excellent electrical conductivity (1.16 x 10-3 S cm-1). Moreover, CGTX-I3 composite hydrogels have excellent adhesion to commonly used substrate materials, especially human skin (130.9 kPa). The CGTX-I3 hydrogel can also detect the deformation caused by an external force and human movements, such as finger bending, elbow movement, wrist movement, ankle movement, and other subtle human actions (such as swallowing and smiling). After 1000 cycles, the sensor can still maintain a stable sensitivity factor (GF = 2.14). It is essential to diagnose Parkinsonism at an early stage to prevent functional impairments in patients and improve their level of healthcare.

关键词： Hydrogels

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Selective laser melting of bulk immiscible alloy with enhanced strength:Heterogeneous microstructure and deformation mechanisms

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Journal of Materials Science & Technology 2022年第9期104卷 81-87页

作者： Shengfeng Zhou Min Xie Changyi Wu Yanliang Yi Dongchu Chen Lai-Chang Zhang MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou 510632China School of Materials Science and Engineering Tianjin Polytechnic UniversityTianjin 300387China Department of Educational Science Hunan First Normal UniversityChangsha 410205China School of Materials Science and Energy Engineering Foshan UniversityFoshan 528225China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia

To overcome the dimension limits of immiscible alloys produced by traditional techniques and enhance their mechanical properties,bulk Cu-Fe-based immiscible alloy with abundant nanotwins and stacking faults was successfully produced by selective laser melting(SLM).The SLM-produced bulk immiscible alloy displays a heterogeneous microstructure characterized by micro-scaledγ-Fe particles dispersed in fineε-Cu matrix with a high fraction(~92%)of high-angle grain ***,abundant nanotwins and stacking faults are generated in the interior of nano-scaledγ-Fe particles embedded withinε-Cu *** heterogeneous interface of soft domains(ε-Cu)and hard domains(γ-Fe)not only induces the geometrically necessary dislocations(GNDs)but also affects the dislocation propagation during plastic ***,the bimodal heterogeneous interface,and the resistance of nanotwins and stacking faults to the propagation of partial dislocation make the bulk immiscible alloy exhibit an enhanced strength of~590 MPa and a good ductility of~8.9%.

关键词： Immiscible alloy Selective laser melting Heterogeneous microstructure Nanotwins Stacking faults

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