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An improved elastoplastic model for rocks and application to cyclic loading and unloading triaxial compression tests

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Acta Mechanica Sinica 2024年第8期40卷 179-193页

作者： Qiuxin Gu Qiang Zhang Yapeng Li Peinan Wu Guilei Han State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou221116China North China Engineering Investigation Institute Shijiazhuang050021China

The recoverable strain of rock is completely classified as elastic strain in the conventional elastic-plastic theory,which often results in poor agreement between theoretical and experimental *** work proposes an improved elastoplastic model of rock materials considering the evolutions of crack deformation and elastic modulus to better characterize the nonlinear mechanical behavior of rock in the post-peak *** this model,the recoverable strain is assumed to be a combination of elastic and crack strain,and the constitutive relationship between crack strain and rock stress is *** on the proposed assumption,the evolutions of the mechanical parameters including strength parameters,elastic,plastic,and crack deformation parameters versus the plastic strain and confining stress were *** developed elastoplastic model was validated by comparing the theoretical values with the results of the triaxial cyclic loading and unloading *** theoretical calculation results show a good agreement with the laboratory test,which indicates that the improved elastoplastic model can effectively reflect the nonlinear mechanical behavior of the rock *** research results are expected to provide a valuable reference for further understanding the evolution of rock crack deformation.

关键词： Crack strain Elastic modulus deterioration Novel elastoplastic model Model validation

Dynamic properties of rumor propagation model induced by L´evy noise on social networks

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Chinese Physics B 2024年第9期33卷 223-237页

作者： Ying Jing Youguo Wang Qiqing Zhai Xianli Sun School of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China School of Telecommunication and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing 210023China

Social networks are inevitably subject to disruptions from the physical world,such as sudden internet outages that sever local connections and impede information *** Gaussian white noise,commonly used to simulate stochastic disruptions,only fluctuates within a narrow range around its mean and fails to capture large-scale variations,L´evy noise can effectively compensate for this ***,a susceptible–infected–removed rumor propagation model with L´evy noise is constructed on homogeneous and heterogeneous networks,***,the existence of a global positive solution and the asymptotic path-wise of the solution are derived on heterogeneous networks,and the sufficient conditions of rumor extinction and persistence are ***,theoretical results are verified through numerical calculations and the sensitivity analysis related to the threshold is conducted on the model *** simulation experiments on Watts–Strogatz(WS)and Barab´asi–Albert networks,it is found that the addition of noise can inhibit the spread of rumors,resulting in a stochastic resonance phenomenon,and the optimal noise intensity is obtained on the WS *** validity of the model is verified on three real datasets by particle swarm optimization algorithm.

关键词： rumor propagation model L´evy noise extinction and persistence stochastic resonance

Numerical analysis of the effects of subgrade settlement on top-down cracking in epoxy asphalt pavement

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Science China Technological Sciences 2024年第10期67卷 3308-3320页

作者： JIANG XiuJie HUANG Wei LUO Sang WEI Ya KONG WeiYi DU KaiJun School of Transportation Southeast University Intelligent Transportation System Research Center Southeast University Department of Civil Engineering Tsinghua University Nanjing Modern Multimodal Transportation Laboratory

Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads. A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking(TDC). The contour integral method is utilized to calculate the stress intensity factor(SIF)at the crack tip, and then the extended finite element method(XFEM) is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading. The results of these analyses indicate that increased subgrade settlement,stiffer surface layers, and softer bases will increase the SIF, resulting in a faster crack propagation rate. It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt ***, when the base layer modulus is higher than 12500 MPa, the increase in surface modulus can decrease crack propagation length. Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation. The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.

关键词： epoxy asphalt pavement subgrade settlement XFEM stress intensity factor crack propagation

Kinetic model of vibration screening for granular materials based on biological neural network

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Particuology 2024年第5期88卷 98-106页

作者： Zhan Zhao Yan Zhang Fang Qin Mingzhi Jin School of Agricultural Engineering Jiangsu UniversityZhenjiang212013China Shandong Academy of Agricultural Machinery Sciences Ji'nan250100China

The kinetic model is the theoretical basis for optimizing the structure and operation performance of vibration screening *** this paper,a biological neurodynamic equation and neural connections were established according to the motion and interaction properties of the material under vibration *** material feeding to the screen and the material passing through apertures were considered as excitatory and inhibitory inputs,respectively,and the generated stable neural activity landscape was used to describe the material distribution on the 2D screen *** dynamic process of material vibration screening was simulated using discrete element method(DEM).By comparing the similarity between the material distribution established using biological neural network(BNN)and that obtained using DEM simulation,the optimum coefficients of BNN model under a certain screening parameter were determined,that is,one relationship between the BNN model coefficients and the screening operation parameters was *** screening parameters were randomly selected,and the corresponding relationships were established as a ***,with straw/grain ratio,aperture diameter,inclination angle,vibration strength in normal and tangential directions as inputs,five independent adaptive neuro-fuzzy inference systems(ANFIS)were established to predict the optimum BNN model coefficients,*** training results indicated that ANFIS models had good stability and *** flexibility and adaptability of the proposed BNN method was demonstrated by modeling material distribution under complex feeding conditions such as multiple regions and non-uniform rate.

关键词： Kinetic model Material distribution Vibration screening Biological neural network DEM simulation Adaptive neuro-fuzzy inference systems

Performance-control-orientated hybrid metal additive manufacturing technologies:state of the art,challenges,and future trends

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International Journal of Extreme Manufacturing 2024年第3期6卷 274-328页

作者： Jiming Lv Yuchen Liang Xiang Xu Gang Xu Hongmei Zhang Haifei Lu Kaiyu Luo Jie Cai Jinzhong Lu School of Mechanical Engineering Jiangsu UniversityZhenjiang 212013People’s Republic of China School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003People’s Republic of China

Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the ***,performance instability during continuous processing,such as thermal history,residual stress accumulation,and columnar grain epitaxial growth,consistently hinders their broad application in standardized industrial *** overcome these challenges,performance-control-oriented hybrid AM(HAM)technologies have been *** technologies,by leveraging external auxiliary processes,aim to regulate microstructural evolution and mechanical properties during metal *** paper provides a systematic and detailed review of performance-control-oriented HAM technology,which is categorized into two main groups:energy field-assisted AM(EFed AM,***,electromagnetic,and heat)technologies and interlayer plastic deformation-assisted AM(IPDed AM,*** shock peening,rolling,ultrasonic peening,and friction stir process)*** review covers the influence of external energy fields on the melting,flow,and solidification behavior of materials,and the regulatory effects of interlayer plastic deformation on grain refinement,nucleation,and ***,the role of performance-control-oriented HAM technologies in managing residual stress conversion,metallurgical defect closure,mechanical property improvement,and anisotropy regulation is thoroughly reviewed and *** review concludes with an analysis of future development trends in EFed AM and IPDed AM technologies.

关键词： hybrid additive manufacturing in-situ/interlayer plastic deformation auxiliary energy fields microstructure customization mechanical properties enhancement

Composite structure Al_(2)O_(3)/Al_(2)O_(3)-YAG:Ce/YAG ceramics with high color spatial uniformity for white laser lighting

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Journal of Advanced Ceramics 2024年第2期13卷 189-197页

作者： Pengfei Sang Le Zhang Jian Kang Mingzhou Li Shiwei Chen Peng Yang Bingheng Sun Yang Li Wieslaw Strek Hao Chen jiangsu Key Laboratory of Advanced Laser Materials and Devices School of Physics and Electronics EngineeringJiangsu Normal UniversityXuzhou 221116China jiangsu Xiyi Advanced Materials Research Institute of Industrial Technology Xuzhou 221400China Xuzhou EAGLED Technology Co. Ltd.Xuzhou 221116China Xuzhou Kangna Advanced Materials Technology Co. Ltd.Xuzhou 221116China Xuzhou Fuchang Electronic Technology Co. Ltd.Xuzhou 221116China Shanghai Institute of Optics Fine Mechanics Chinese Academy of SciencesShanghai 201800China School of Material Science and Engineering Shanghai Institute of TechnologyShanghai 201418China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China Institute of Low Temperature and Structure Research Polish Academy of SciencesWroclaw 50-422Poland

Composite ceramic phosphor(CCP)is a candidate light-conversion material to obtain the high-quality laser lighting *** based on the transmissive configuration model could not simultaneously meet the requirements of angular color uniformity and high thermal *** this study,a novel composite structure ceramic was designed,including Al_(2)O_(3)-YAG:Ce/YAG layered ceramic with a size of 1 mm×1 mm for lighting,and Al_(2)O_(3) ceramic(φ=16.0 mm)was used as the wrapping material due to its outstanding thermal *** prepared ceramics exhibited excellent thermal performance and no yellow ring *** this design,we achieved the match of the intensity distribution of the blue and yellow lights,resulting in a high angular color uniformity of 0.9 with a view angle of±80°.All ceramics showed no luminous saturation phenomenon,even the laser power density was increased up to 47.51 W/mm^(2).A high-brightness white-light source with a luminous flux of 618 lm,a luminous efficiency of 126 lm/W,a CCT of 6615 K,and a CRI of 69.9 was obtained in the transmissive *** particular,the surface temperature of the ceramic was as low as 74.1℃ under a high laser radiation(47.51 W/mm^(2)).These results indicate that Al_(2)O_(3)/Al_(2)O_(3)-YAG:Ce/YAG composite structure ceramic is a promising luminescent material in the high-power laser lighting applications.

关键词： Al_(2)O_(3)/Al_(2)O_(3)-YAG:Ce/YAG angular color uniformity high thermal stability high-power laser lighting

Failure evolution and disaster prediction of rock under uniaxial compression based on non-extensive statistical analysis of electric potential

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International Journal of Mining Science and Technology 2024年第7期34卷 975-993页

作者： Tiancheng Shan Zhonghui Li Haishan Jia Enyuan Wang Xiaoran Wang Yue Niu Xin Zhang Dong Chen Shan Yin Quancong Zhang State Key Laboratory of Coal Mine Disaster Prevention and Control China University of Mining and TechnologyXuzhou 221116China National Engineering Research Center for Coal Gas Control China University of Mining and TechnologyXuzhou 221116China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China

Rock failure can cause serious geological disasters,and the non-extensive statistical features of electric potential(EP)are expected to provide valuable information for disaster *** this paper,the uniaxial compression experiments with EP monitoring were carried out on fine sandstone,marble and granite samples under four displacement *** Tsallis entropy q value of EPs is used to analyze the selforganization evolution of rock *** the influence of displacement rate and rock type on q value are explored by mineral structure and fracture modes.A self-organized critical prediction method with q value is *** results show that the probability density function(PDF)of EPs follows the q-Gaussian *** displacement rate is positively correlated with q *** the displacement rate increasing,the fracture mode changes,the damage degree intensifies,and the microcrack network becomes *** influence of rock type on q value is related to the burst intensity of energy release and the crack fracture *** q value of EPs can be used as an effective prediction index for rock failure like b value of acoustic emission(AE).The results provide useful reference and method for the monitoring and early warning of geological disasters.

关键词： Electric potential Non-extensive statistical feature Displacement rate q-Gaussian distribution Precursor prediction Rock materials

Fluidization stability and periodic fluctuations in gas–solid separation fluidized bed using Geldart A dense medium

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Particuology 2024年第7期90卷 522-534页

作者： Weijin Liu Dan Wang Liang Dong Enhui Zhou Tatiana Aleksandrova Chenyang Zhou Chenlong Duan Key Laboratory of Coal Processing and Efficient Utilization(China University of Mining&Technology) Ministry of EducationXuzhou 221116China School of Chemical Engineering&Technology China University of Mining&TechnologyXuzhou 221116China Department of Chemical and Biochemical Engineering The University of Western OntarioLondonOntario N6A 5B9Canada Mineral Processing Department Saint Petersburg Mining UniversitySt.Petersburg 199106Russia

Gas–solid separation fluidized bed is a typical method for coal separation without water *** A particles is also considered as the ideal dense medium to strengthen separation *** stability reflects the bed pressure fluctuations and the distribution of bubble and emulsion phases,affecting the separation *** the main frequency of pressure fluctuations can directly reflect the degree of pressure ***,the detailed fluidization stability is analyzed combined the method of standard deviation of pressure fluctuations,power spectral density,etc.,for Geldart A *** results showed that maintaining an appropriate gas velocity resulted in an average bed pressure of around 2000 *** main frequency is mainly concentrated around 1–1.5 ***,a prediction model of the main frequency of pressure fluctuations is established,and the error can be controlled within±*** investigation further proved the stable fluidization of Geldart A particles and provides a method for predicting the main frequency of pressure fluctuations in the gas–solid separation fluidized bed.

关键词： Geldart A dense medium Fluidization stability Periodic fluctuations Pressure fluctuations frequency Gas–solid separation fluidized bed

Characteristics and Mechanisms of Persistent Wet–Cold Events with Different Cold-air Paths in South China

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Advances in Atmospheric Sciences 2024年第6期41卷 1171-1183页

作者： Xiaojuan SUN Li CHEN Chuhan LU Panxing WANG Key Laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Qianxinan Bouyei and Miao Autonomous Prefecture Meteorological Bureau of Guizhou province Xingyi 562400China

We investigate the characteristics and mechanisms of persistent wet–cold events(PWCEs)with different types of coldair *** show that the cumulative single-station frequency of the PWCEs in the western part of South China is higher than that in the eastern *** pattern of single-station frequency of the PWCEs are“Yangtze River(YR)uniform”and“east–west inverse”.The YR uniform pattern is the dominant mode,so we focus on this *** cold-air paths for PWCEs of the YR uniform pattern are divided into three types—namely,the west,northwest and north types—among which the west type accounts for the largest *** differences in atmospheric circulation of the PWCEs under the three types of paths are *** thermal inversion layer in the lower troposphere is favorable for precipitation during the *** positive water vapor budget for the three types of PWCEs mainly appears at the southern boundary.

关键词： persistent wet–cold events cold-air paths circulation characteristics water vapor