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SSRN 2023年

作者： Li, Zhihao Zhou, Wei School of Civil Engineering Key Lab of Structures Dynamic Behavior and Control Ministry of Education Key Lab of Smart Prevention and Mitigation of Civil Engineering Disaster Ministry of Industry and Information Technology Harbin Institute of Technology 73 Huanghe Road Nangang District Harbin150090 China

Ultra-High-Performance Fiber Reinforced Concrete (UHPFRC) not only has high compressive and tensile strength, but also exhibits strain-hardening characteristics in tension due to the addition of steel fibers. In this study, a new-style fiber orientation device equipped with a vibration motor of adjustable vibrational frequency was used to prepare UHPFRC. The wall effect and fiber length were considered in the manufacturing process of the device. Uniaxial tensile tests were conducted on fiber-oriented UHPFRC to explore the effects of vibrational frequency and corresponding vibrational force on the tensile behaviors. The test results showed that the elastic ultimate tensile strength, elastic ultimate tensile strain, tensile strength, peak tensile strain, and tensile elastic modulus of UHPFRC specimens cast by fiber orientation process at various vibrational frequencies were different. The fiber orientation parameters were quantitatively evaluated by the image analysis technique to explain the differences in tensile properties of the specimens. The effect of different vibrational frequencies on the tensile strength of UHPFRC matrix and its porosity was also considered. Therefore, this study provides a reference for how to adjust the vibrational frequency of the vibrating platform under the directional channel when pouring relevant components. © 2023, The Authors. All rights reserved.

关键词： Steel fibers

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An Experimental Investigation of the Influence of Loading Rate on Rock Tensile Strength and Split Fracture Surface Morphology

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ROCK MECHANICS AND ROCK engineering 2021年第4期54卷 1969-1983页

作者： Cui, Zhen Qian, Sheng Zhang, Guimin Maochu, Zhang Chinese Acad Sci State Key Lab Geomech & Geotech Engn Inst Rock & Soil Mech Wuhan 430071 Hubei Peoples R China Univ Chinese Acad Sci Sch Engn Sci Beijing 10049 Peoples R China China Univ Min & Technol State Key Lab GeoMech & Deep Underground Engn Xuzhou 221116 Jiangsu Peoples R China Changjiang River Sci Res Inst Minist Water Resources Key Lab Geotech Mech & Engn Wuhan 430010 Hubei Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

To investigate the effect of the loading rate on the tensile strength of rock material and the morphology of the resulting split fracture surfaces, three types of rock specimens, namely, granite, basalt and limestone, were collected and tested with Brazilian testing under different loading rates. The tensile strength was measured, and the effect of the loading rate on the tensile strength of the rock material was studied. Digital terrain map models of the split fracture surface were obtained with an optical 3D scanning technique, and the effects of the loading rate on the geometry and morphology of the fracture surface were studied. The influence of the loading rate and tensile strength on the roughness was studied quantitatively by calculating the roughness indices of a fracture surface for all three kinds of rock. The research results show that the rock tensile strength increases with the loading rate. A linear relationship was established in double-logarithmic coordinates to describe the relationship between the tensile strength and the loading rate. Four different roughness indices were used to describe the morphology of the split fracture surface. The analysis results show that the magnitudes of all the roughness indices increase with the loading rate. Additionally, the roughness indices for all three types of rock linearly increase with the tensile strength. This linear trend indicates that it is possible to utilize fracture surface roughness indices to estimate rock tensile strength. The current study may motivate further research on the relationship between the morphology indices of rock fractures and mechanical parameters of the rock.

关键词： Rock material Brazilian test Loading rate Tensile strength Fracture surface morphology

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An analytical method for shallow spherical shell free vibration on two-parameter foundation

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HELIYON 2021年第1期7卷 e05876页

作者： Gan, Jiarong Yuan, Hong Li, Shanqing Peng, Qifeng Zhang, Huanliang Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

The free vibration control differential equation of shallow spherical shell on two-parameter foundation is a four order differential equation. Using the intermediate variable, the four order differential equation is reduced to two lower order differential equations. The first lower order differential equation is a Helmholtz equation. A new method of two-dimensional Helmholtz operator is proposed as shown in the paper in which the Bessel function included in Helmholtz equation needs to be treated appropriately to eliminate singularity. The first lower order differential equation is transformed into the integral equation using the proposed method in the paper. The second lower order differential equation which is a Laplace equation is transformed into the integral equation by existing methods. Then the two integral equations are discretized according to the middle rectangle formula, and the corresponding solutions can be obtained by MATlab programming. In this paper, the R-function theory is used to select the appropriate boundary equation to eliminate the singularity. Based on the properties of R-function, the combined method of Helmholtz equation and Laplace equation can solve the free vibration problem of irregular shallow spherical shell on two-parameter foundation. Five examples are given to verify the feasibility of the method.

关键词： Shallow spherical shell Two-parameter foundation Helmholtz equation Laplace equation R-function Green's function

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Indirect Reconstruction of Structural Responses Based on Transmissibility Concept and Matrix Regularization

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SHOCK AND VIBRATION 2021年第1期2021卷

作者： Pan, Chudong Zhang, Liwen Sun, Zhuo Guangzhou Univ Sch Civil Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

A novel method is proposed based on the transmissibility concept and matrix regularization for indirectly measuring the structural responses. The inputs are some measured responses that are obtained via physical sensors. The outputs are the structural responses corresponding to some critical locations where no physical sensors are installed. Firstly, the transmissibility concept is introduced for expressing the relationship between the measured responses and the indirectly measured ones. Herein, a transmissibility matrix is formulated according to the theory of force identification under unknown initial conditions. Then, in order to reduce the size of the transmissibility matrix, structural responses are reshaped in a form of a matrix by using the concept of moving time windows. According to the matrix form of input-output relationship, indirect reconstruction of responses is boiled down to an optimization equation. Since inverse problem may be ill-conditioned, matrix regularization such as F-norm regularization is then recommended for improving the optimization problem. Herein, the penalty function is defined by using a weighted sum of two F-nonn values, which correspond to the estimated responses of physical sensors and the ones of the concerned critical locations, respectively. Numerical simulations and experimental studies are finally carried out for verifying the effectiveness and feasibility of the proposed method. Some results show that the proposed method can be applied for indirectly measuring the responses with good robustness.

关键词： Matrix algebra

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Computer transient simulation for dual in-line package through finite element analysis and ANASYS software 3

Computer transient simulation for dual in-line package throu...

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3rd International Conference on Electrical, Communication and Computer engineering, ICECCE 2021

作者： Su, Wei Luo, Wenhao Dong, Xianshan Chen, Si Tomar, Agam Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia Australia

The reliability of the DIP package is studied by numerical simulation. Firstly, the DIP package, fixture and metal steel are modeled. Based on this, variable thickness papers are laid on the sample. According to the experiment, corresponding excitation and boundary condition are set. Then, the transient analysis result of DIP package is obtained through numerical simulation. The results show the relation of different thickness papers and acceleration-time curve, which provides a beneficial reference for the optimization of DIP packing. © 2021 Institute of Physics Publishing. All rights reserved.

关键词： Transient analysis

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A new micro-macro transition for hyperelastic materials

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2023年 171卷

作者： Zhan, Lin Wang, Siyu Qu, Shaoxing Steinmann, Paul Xiao, Rui Zhejiang Univ Dept Engn Mech State Key Lab Fluid Power & Mechatron Syst Key Lab Soft Machines & Smart Devices Zhejiang Pr Hangzhou 310027 Peoples R China Jinan Univ Coll Mech & Construct Engn Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Friedrich Alexander Univ Erlangen Nuremberg Inst Appl Mech Egerland Str 5 D-91058 Erlangen Germany

Many classic hyperelastic models fail to predict the stress responses of soft materials in complex loading conditions with parameters calibrated through one simple test. To address this fundamental issue, we propose a new micro-macro transition for the microstructural hyperelasticity modeling, which is further integrated into the full network framework. With a Gaussian chain distribution, this new mapping scheme yields an explicit one-parameter hyperelastic model in terms of principal stretches. This new linear model achieves remarkable success in capturing the stress responses in multi-axial deformation modes for soft materials with an absence of strain stiffening effect, which is beyond the capability of the widely used neo-Hookean model. A new two-parameter hyperelastic model is further developed by combining the new micro-macro transition and non-Gaussian Langevin chain distribution. Compared with other two-parameter hyperelastic models based on Langevin statistics, such as the eight-chain model, affine full network model, and equilibrated microsphere model, our new model exhibits greatly improved predictive ability for complex loading types. The new model is also implemented for finite element analysis, which shows the ability to capture the responses of soft materials with heterogeneous strain distribution. In all cases, the parameters in our models can be determined through the data of uniaxial loading tests, along with the behaviors in other loading modes being well forecast, which is a challenge for various other existing hyperelastic models. This novel micro-macro transition is shown to properly capture the inherent correlations between different deformation modes, which may advance fundamentally modeling hyperelasticity and other constitutive behaviors for soft materials.

关键词： Micro-macro transition Hyperelastic model Multi-axial deformation Finite element simulation

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Seasonal to interannual prediction of air pollution in China:Review and insight

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Atmospheric and Oceanic Science Letters 2022年第1期15卷 21-26页

作者： Zhicong Yin Huijun Wang Hong Liao Ke Fan Botao Zhou Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjingChina Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) ZhuhaiChina Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjingChina School of Atmospheric Sciences Sun Yat-sen University/Guangdong Province Key Laboratory for Climate Change and Natural Disaster StudiesGuangzhouChina

Complex air pollution problems have resulted in considerable adverse impacts on the environment,human health,and economy in ***,owing to strict regulations since 2013,the air quality has been greatly ***,the prevention of air pollution has entered a critical stage in combination with climate change mitigation in *** seasonal to interannual prediction of air pollution(haze,surface 03,and sandstorms) could support the government in planning for air pollution control on an annual *** from all over the world have made great progress in understanding climate change and the variability of air pollution and associated physical mechanisms in China,which has provided a scientific basis for the development of climate prediction of air *** paper reviews the progress made in air-pollution climate prediction,and gives some critical insights including update of predictand,change of predictability,and development of coupled model.

关键词： Air pollution Climate prediction PM2.5 Ozone Sandstorm

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Moving force identification based on sparse regularization combined with moving average constraint

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JOURNAL OF SOUND AND VIBRATION 2021年 515卷 116496-116496页

作者： Pan, Chudong Huang, Zhenjie You, Junda Li, Yisha Yang, Lihua Guangzhou Univ Sch Civil Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

An accurate input-output mathematical model is the basis of moving force identification (MFI). However, an absolutely accurate mathematical model between moving forces and structural responses is difficult to be established due to some practical reasons, such as calibration error, modelling error, and so on. An inaccurate input-output relationship may lead to some unreasonable MFI results, for example, an obvious fluctuation of the trend lines in moving forces. To tackle this problem, a constrained sparse regularization-based method is proposed for MFI in this study. Wherein, structural responses obtained from sensors with calibration errors are taken as the inputs. A system matrix reflecting the input-output relationship is formulated in the consideration of unknown moving forces and initial conditions. Sparse regularization is adopted for ensuring that the identified forces are sparse and robust. The constrained condition is expressed as a non-negative function. This function is defined via a strategy named moving average and applied for reflecting the degree of fluctuation of the trend lines for the moving forces. The constrained problem is solved as a standard form of l1-norm regularization via relaxing the constrained condition appropriately. Numerical simulations and experimental studies are conducted for assessing the effectiveness and feasibility of the proposed method. Effects of different calibration errors of sensors are discussed in detail. Illustrated results show that the proposed method can reconstruct the moving forces with a good performance. Some related issues are discussed as well.

关键词： Moving force identification Sparse regularization Moving average constraint Inverse problem Calibration error

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Harmonic response analysis for ball grid array package using computer finite element simulation 3

Harmonic response analysis for ball grid array package using...

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3rd International Conference on Electrical, Communication and Computer engineering, ICECCE 2021

BGA package is selected as the research object in this paper. Workbench (finite elemental analysis tool in ANSYS) is used for harmonic response analysis. The author lays several paper sheets on the sample and builds the finite element model of clamp, ceramic and metal plate. Then, the model analysis is carried out. Based on this, it is converted to harmonic response analysis. According to the results, the author has found that there is no relation between the number of paper sheets and acceleration-frequency result. It promotes the development of electronic packaging reliability. © 2021 Institute of Physics Publishing. All rights reserved.

关键词： Finite element method

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Residual stress analysis of laser welding between output needle and helix 7

Residual stress analysis of laser welding between output nee...

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2020 7th International Conference on Computer-Aided Design, Manufacturing, Modeling and Simulation, CDMMS 2020

作者： Su, Wei Luo, Wenhao Dong, Xianshan Liu, Renhuai MOE Key Lab of Disaster Forecast and Control in Engineering Guangzhou510632 China Sci. and Technol. on Reliability Phys. and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou510610 China School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China

In order to obtain the welding stress of the output needle and helix, a finite element model is established and the mesh at the weld is refined to evaluate the welding residual stress. ANSYS parameter design language is used to simulate the motion load of welding heat source. Based on the exact calculation of the temperature field, the corresponding thermal units are converted into structural units to calculate the welding residual stress. Finally, the thermal stress distribution curve and residual stress distribution trend are obtained after post-treatment. © 2021 Institute of Physics Publishing. All rights reserved.

关键词： Residual stresses

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