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Updated Lagrangian Particle Hydrodynamics (ULPH)Modeling of Natural Convection Problems

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Computer Modeling in engineering & Sciences 2024年第10期141卷 151-169页

作者： Junsong Xiong Zhen Wang Shaofan Li Xin Lai Lisheng Liu Xiang Liu Hubei Key Laboratory of Theory and Application of Advanced Materials mechanics Wuhan University of TechnologyWuhan430070China Department of engineering Structure and mechanics Wuhan University of TechnologyWuhan430070China Department of Civil and Environmental engineering The University of CaliforniaBerkeleyCA 94720USA

Natural convection is a heat transfer mechanism driven by temperature or density differences,leading to fluid motion without external *** occurs in various natural and engineering phenomena,influencing heat transfer,climate,and fluid mixing in industrial *** work aims to use the Updated Lagrangian Particle Hydrodynamics(ULPH)theory to address natural convection *** Navier-Stokes equation is discretized using second-order nonlocal differential operators,allowing a direct solution of the Laplace operator for temperature in the energy *** numerical simulations,including cases such as natural convection in square cavities and two concentric cylinders,were conducted to validate the reliability of the *** results demonstrate that the proposed model exhibits excellent accuracy and performance,providing a promising and effective numerical approach for natural convection problems.

关键词： Updated Lagrangian particle hydrodynamics(ULPH) natural convection meshless methods higher order Laplacian model

Analytical Expression for the Atomic Friction of a Single Asperity Based on the Prandtl-Tomlinson Model

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Acta Mechanica Solida Sinica 2024年第3期37卷 416-422页

作者： Weike Yuan Yue Ding Gangfeng Wang Xinrui Niu Department of engineering mechanics SVLMMLXi’an Jiaotong UniversityXi’an710049China Department of Mechanical engineering City University of Hong KongHong Kong SAR999077China

The Prandtl-Tomlinson(PT)model has been widely applied to interpret the atomic friction mechanism of a single *** this study,we present an approximate explicit expression for the friction force in the one-dimensional PT model under quasi-static ***‘stick-slip’friction curves are first approximated properly by sawtooth-like lines,where the critical points before and after the‘slip’motion are described analytically in terms of a dimensionless parameterη.Following this,the average friction force is expressed in a closed form that remains continuous and valid forη>***,an analytical expression for the load dependence of atomic friction of a single asperity is derived by connecting the parameterηwith the normal *** the parameters reported in experiments,our prediction shows good agreement with relevant experimental results.

关键词： Atomic friction Stick-slip friction Prandtl-Tomlinson model Friction force microscope

An Updated Lagrangian Particle Hydrodynamics (ULPH)-NOSBPD Coupling Approach forModeling Fluid-Structure Interaction Problem

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Computer Modeling in engineering & Sciences 2024年第10期141卷 491-523页

作者： Zhen Wang Junsong Xiong Shaofan Li Xin Lai Xiang Liu Lisheng Liu Hubei Key Laboratory of Theory and Application of Advanced Materials mechanics Wuhan University of TechnologyWuhan430070China Department of Civil and Environmental engineering The University of CaliforniaBerkeleyCA 94720USA Department of engineering Structure and mechanics Wuhan University of TechnologyWuhan430070China

A fluid-structure interaction approach is proposed in this paper based onNon-Ordinary State-Based Peridynamics(NOSB-PD)and Updated Lagrangian Particle Hydrodynamics(ULPH)to simulate the fluid-structure interaction problem with large geometric deformation and material failure and solve the fluid-structure interaction problem of Newtonian *** the coupled framework,the NOSB-PD theory describes the deformation and fracture of the solid material *** is applied to describe the flow of Newtonian fluids due to its advantages in computational *** framework utilizes the advantages of NOSB-PD theory for solving discontinuous problems and ULPH theory for solving fluid problems,with good computational stability and robustness.A fluidstructure coupling algorithm using pressure as the transmission medium is established to deal with the fluidstructure *** dynamic model of solid structure and the PD-ULPH fluid-structure interaction model involving large deformation are verified by numerical *** results agree with the analytical solution,the available experimental data,and other numerical ***,the accuracy and effectiveness of the proposed method in solving the fluid-structure interaction problem are *** fluid-structure interactionmodel based on ULPH and NOSB-PD established in this paper provides a new idea for the numerical solution of fluidstructure interaction and a promising approach for engineering design and experimental prediction.

关键词： Fluid-structure interaction(FSI) updated lagrangian particle hydrodynamics peridynamics meshfree method

A Novel On-Site-Real-Time Method for Identifying Characteristic Parameters Using Ultrasonic Echo Groups and Neural Network

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Chinese Journal of Mechanical engineering 2024年第1期37卷 215-228页

作者： Shuyong Duan Jialin Zhang Heng Ouyang Xu Han Guirong Liu State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjin 300401China Department of Aerospace engineering and engineering mechanics University of CincinnatiCincinnati 45221USA

On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness,nonuniform material *** work develops for the first time a method that uses ultrasound echo groups and artificial neural network(ANN)for reliable on-site real-time identification of material *** use of echo groups allows the use of lower frequencies,and hence more accommodative to structural *** train the ANNs,a numerical model is established that is capable of computing the waveform of ultrasonic echo groups for any given set of material properties of a given *** waveform of an ultrasonic echo groups at an interest location on the surface the structure with material parameters varying in a predefined range are then computed using the numerical *** results in a set of dataset for training the ANN *** the ANN is trained,the material parameters can be identified simultaneously using the actual measured echo waveform as input to the *** tests have been conducted both numerically and experimentally to evaluate the effectiveness and accuracy of the currently proposed *** results show that the maximum identification error of numerical example is less than 2%,and the maximum identification error of experimental test is less than 7%.Compared with currently prevailing methods and equipment,the proposefy the density and thickness,in addition to the elastic ***,the reliability and accuracy of inverse prediction is significantly ***,it has broad applications and enables real-time field measurements,which has not been fulfilled by any other available methods or equipment.

关键词： Parameter identification Ultrasonic echo group High-precision modeling Artificial neural network NDT

Prediction and Regulation of Delamination at Flexible Film/Finite-Thickness-Substrate Structure Interfaces

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Acta Mechanica Solida Sinica 2024年第2期37卷 238-251页

作者： Yutang Zhou Yunlong Xu Haoran Gong Chenyu Wang Department of engineering mechanics Northwestern Polytechnical UniversityXi’an710072China School of Instrumentation Science and Opto-Electronics engineering Beihang UniversityBeijing100191China

Regulating the surface instability of thin film/substrate structures has been successfully applied to prepare new ductile electronic ***,such electronic devices need to be subjected to external loads during operation,which can easily induce delamination of the thin-film electronic device from the *** study aims to investigate the instability characteristics of hard films on flexible substrate surfaces from theoretical analysis and numerical simulation *** finite-thickness substrates,this paper establishes theoretical models for pure bending,bent wrinkle,partial delamination,and total delamination buckling of film/substrate structures based on the nonlinear Euler–Bernoulli beam theory and the principle of minimum energy;then the effects of material and geometric parameters of the structure,interfacial adhesion strength,and pre-strain on the evolutionary path of the four patterns are *** study results show that:the greater Young’s modulus of the substrate is,the larger the parameter region where partial delamination of the film/substrate structure occurs,and the smaller the parameter region where bent wrinkle *** varying Young’s modulus,thickness of the film and substrate,interfacial adhesion coefficient,and pre-strain,the buckling pattern of the structure can be predicted and *** parametric design intervals for each pattern are summarized in the phase *** results of this paper provide theoretical support for the design and reliability evaluation of flexible electronic devices.

关键词： Thin film/finite-thickness-substrate structure Delamination Surface instability Pattern evolution

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 mechanics and Safety engineering Zhengzhou UniversityZhengzhou 450001China Department of Mechanical engineering and mechanics 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

A Comprehensive Study of a Low-Grade Heat-Driven Cooling and Power System Based on Heat Current Method

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Journal of Thermal Science 2024年第4期33卷 1523-1541页

作者： ZHAO Tian XU Ronghong XIN Yonglin HE Kelun MA Huan YUAN Mengdi CHEN Qun School of Energy Storage Science and engineering North China University of TechnologyBeijing100144China Key Laboratory for Thermal Science and Power engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing100084China

Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy *** work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption chiller on both driving and cooling fluid *** system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior *** off-design system simulation is performed next,showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system *** off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components,highlighting the importance of considering heat transfer constraints via heat current *** optimization aiming to minimize the total thermal conductance is also *** efficiency increases by 7.9%and decreases by 12.4%after optimization,with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s,emphasizing the necessity of balancing system cost and performance.

关键词： combined cooling and power system organic Rankine cycle absorption chiller cascade heat utilization heat current method off-design analysis

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Deciphering the controlling factors for phase transitions in zeolitic imidazolate frameworks

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National Science Review 2024年第4期11卷 151-163页

作者： Tao Du Shanwu Li Sudheer Ganisetti Mathieu Bauchy Yuanzheng Yue Morten M.Smedskjaer Department of Chemistry and Bioscience Aalborg University Department of Mechanical engineering-engineering mechanics Michigan Technological University Physics of Amo Rphous and Inorganic Solids Laboratory(PARISlab) Department of Civil and Environmental EngineeringUniversity of CaliforniaLos Angeles

Zeolitic imidazolate frameworks（ZIFs） feature complex phase transitions, including polymorphism,melting, vitrification, and polyamorphism. Experimentally probing their structural evolution during transitions involving amorphous phases is a significant challenge, especially at the medium-range length scale. To overcome this challenge, here we first train a deep learning-based force field to identify the structural characteristics of both crystalline and non-crystalline ZIF phases. This allows us to reproduce the structural evolution trend during the melting of crystals and formation of ZIF glasses at various length scales with an accuracy comparable to that of ab initio molecular dynamics, yet at a much lower computational cost. Based on this approach, we propose a new structural descriptor, namely, the ring orientation index, to capture the propensity for crystallization of ZIF-4(Zn（Im）2, Im = C3H3N2-) glasses, as well as for the formation of ZIF-zni(Zn（Im）2) out of the high-density amorphous phase. This crystal formation process is a result of the reorientation of imidazole rings by sacrificing the order of the structure around the zinc-centered tetrahedra. The outcomes of this work are useful for studying phase transitions in other metal-organic frameworks（MOFs） and may thus guide the development of MOF glasses.

关键词： metal-organic frameworks phase transitions melting glass formation transferable deep learning force field ring orientation

Frictional contact analysis of a rigid solid with periodic surface sliding on the thermoelectric material

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Applied Mathematics and mechanics(English Edition) 2024年第1期45卷 179-196页

作者： Yali ZHANG Yueting ZHOU Shenghu DING School of Mathematics and Statistics Ningxia UniversityYinchuan 750021China School of Aerospace engineering and Applied mechanics Tongji UniversityShanghai 200092China

Understanding and characterizing rough contact and wavy surfaces are essential for developing effective strategies to mitigate wear,optimize lubrication,and enhance the overall performance and durability of mechanical *** sliding friction contact problem between a thermoelectric(TE)half-plane and a rigid solid with a periodic wavy surface is the focus of this *** simplify the problem,we utilize mixed boundary conditions,leading to a set of singular integral equations(SIEs)with the Hilbert *** analytical solutions for the energy flux and electric current density are obtained by the variable transform method in the context of the electric and temperature *** contact problem for the elastic field is transformed into the second-kind SIE and solved by the Jacobi ***,the smoothness of the wavy contact surface ensures that there are no singularities in the surface contact stress,and ensures that it remains free at the contact *** on the plane strain theory of elasticity,the analysis primarily examines the correlation between the applied load and the effective contact *** distribution of the normal stress on the surface with or without TE loads is discussed in detail for various friction ***,the obtained results indicate that the in-plane stress decreases behind the trailing edge,while it increases ahead of the trailing edge when subjected to TE loads.

关键词： wavy surface periodic contact thermoelectric(TE)material Hilbert integral kernel

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