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An Improved Enthalpy-Based Lattice Boltzmann 3D Model with Added Probability Function for the Growth Characteristics of Frost Layer

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Journal of Thermal Science 2019年第2期28卷 378-392页

作者： CUI Jing YANG Tinghao YANG Fan YANG Guangfeng Airport College Civil Aviation University of China

In this paper, the effects of different surface properties on the growth of frost layer were numerically studied from the mesoscopic scale using the lattice Boltzmann method. The improved enthalpy method and nucleation probability model were combined to establish a three-dimensional lattice Boltzmann model based on nucleation probability theory. The model was used to carry out numerical research on frost layer formation and growth process on cold wall surface. The model could not only simulate the gradual densification and thickening process of frost layer growth from the macro scale, but also describe the change process of the frost layer structure caused by ice branch growth on the micro scale. The average thickness, average density and the amount of the frost layer could be obtained. Through this model, the temporal and spatial evolution characteristics of the topography of the frost layer were obtained. The model was used to analyze the effects of cold wall surface temperature, relative humidity and cold surface wettability on the frosting characteristics. The average thickness, frost average density, frost quality and average solid volume fraction of frost at different times were obtained by calculation.

关键词： lattice Boltzmann model improved enthalpy model nucleation probability model three-dimensional frost surface wettability

Study on behaviors of functionally graded shape memory alloy cylinder

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Acta Mechanica Solida Sinica 2017年第6期30卷 608-617页

作者： Bingfei Liu Qingfei Wang Rui Zhou Chunzhi Du Yanan Zhang Pan Zhang Airport College Civil Aviation University of China Tianjin 300300 China Aeronautical engineering college Civil Aviation University of China Tianjin 300300 China

For better controllability in actuations,it is desirable to create Functionally Graded Shape Memory Alloys（FG-SMAs）in the actuation direction.It can be achieved by applying different heat treatment processes to create the gradient along the radius of a SMA cylinder.Analytical solutions are derived to predict the macroscopic behaviors of such a functionally graded SMA cylinder.The Tresca yield criterion and linear hardening are used to describe the different phase transformations with different gradient parameters.The numerical results for an example of the model exhibit different pseudo-elastic behaviors from the non-gradient case,as well as a variational hysteresis loop for the transformation,providing a mechanism for easy actuation control.When the gradient disappears,the model can degenerate to the non-gradient case.

关键词： Shape memory alloy Gradient Constitutive model Cylinder Internal pressure

Seismic response characteristics of nuclear island structure at generic soil and rock sites

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 667-688页

作者： Lv Hao Chen Shaolin Department of Civil and airport Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China college of Safety and Environmental Engineering Shandong University of Science and TechnologyQingdao 266590China college Resources Shandong University of Science and TechnologyTai’an 271019China

The number of traditionally excellent coastal lithologic nuclear power plants is limited.It is a trend to develop nuclear power plants on soil sites in inland areas.Therefore,the seismic safety and adaptability of non-rock nuclear power plant(NPP)sites are the key concerns of nuclear safety researchers.Although the five site categories are clearly defined in the AP1000 design control documents,the effects of nuclear power five site conditions and soil nonlinearity on the seismic response characteristics of nuclear island buildings have not been systematically considered in previous related studies.In this study,targeting the AP1000 nuclear island structure as the research object,three-dimensional finite element models of a nuclear island structure at five types of sites(firm rock site(FR),soft rock site(SR),soft-to-medium soil site(SMS),upper bound soft-to-medium site(SMS-UB),and soft soil site(SS))are established.The partitioned analysis method of soil-structure interaction(PASSI)in the time-domain is used to investigate the effects of site hardness and nonlinearity on the acceleration,displacement,and acceleration response spectrum of the nuclear island structure under seismic excitation.The incremental equilibrium equation and explicit decoupling method are used to analyze the soil nonlinearity described by the Davidenkov model with simplified loading-reloading rules.The results show that,in the linear case,with the increase of site hardness,the peak ground acceleration(PGA)and the peak of acceleration response spectrum of the nuclear island structure increase except for the FR site,while the maximum displacement decreases.In nonlinear analysis,as the site hardness increases,the PGA,maximum displacement,and the peak of acceleration response spectrum of the nuclear island structure increase.The peak value of the acceleration response spectrum in the nonlinear case is greater than that in the linear case for FR,while smaller for SR and soil sites.The site nonlinearity reduces the peak values of the response spec

关键词： partitioned analysis for SSI site conditions nuclear structure explicit-implicit integration scheme incremental algorithm for nonlinear analysis

On Behaviors of Functionally Graded SMAs under Thermo-Mechanical Coupling

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Acta Mechanica Solida Sinica 2016年第1期29卷 46-58页

作者： Bingfei Liu Pengcheng Ni Wei Zhang Airport College Civil Aviation University of China Sino-European Institute of Aviation Engineering Civil Aviation University of China

An analytical solution is obtained for the Functionally Graded Shape Memory Alloy （FG-SMA） composites subjected to thermo-mechanical coupling. Young＇s modulus and thermal expansion coefficient of the material are assumed to vary in different forms of power function through the thickness, with the Poisson＇s ratio being constant. An SMA constitutive model is combined with the averaging techniques of composite to determine the mechanical properties of the FG-SMA composites. Different phase transformation steps and the corresponding stress distributions through the thickness direction are given. The results show that the average stresses decrease as the transformations proceed.

关键词： functionally graded SMAs phase transformation constitutive model

MULTI-OBJECTIVE PROGRAMMING FOR airport GATE REASSIGNMENT

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Transactions of Nanjing University of Aeronautics and Astronautics 2013年第2期30卷 209-215页

作者：李军会陈欣朱金福 college of Economics and Management Nanjing University of Aeronautics and Astronautics Guangdong airport Management Company Traffic college Southeast University

To improve the efficiency of gate reassignment and optimize the plan of gate reassignment,the concept of disruption management is introduced,and a multi-objective programming model for airport gate reassignment is proposed.Considering the interests of passengers and the airport,the model minimizes the total flight delay,the total passengers′walking distance and the number of flights reassigned to other gates different from the planned ones.According to the characteristics of the gate reassignment,the model is simplified.As the multi-objective programming model is hard to reach the optimal solutions simultaneously,a threshold of satisfactory solutions of the model is set.Then a simulated annealing algorithm is designed for the model.Case studies show that the model decreases the total flight delay to the satisfactory solutions,and minimizes the total passengers′walking distance.The least change of planned assignment is also reached.The results achieve the goals of disruption management.Therefore,the model is verified to be effective.

关键词： gate assignment multi-objective programming simulated annealing algorithm disruption management

Prediction on CO2 uptake of recycled aggregate concrete

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Frontiers of Structural and Civil Engineering 2020年第3期14卷 746-759页

作者： Kaiwen HUANG Ao LI Bing XIA Tao DING Department of Structural Engineeving College of Civil EngineeringTongji UniversityShanghai 200092China Shanghai International airport Company Limited Shanghai 200152China

Carbonation of concrete is a process which absorbs carbon dioxide (CO2). Recycled aggregate concrete(RAC) may own greater potential in CO2 uptake due to the faster carbonation rate than natural aggregate concrete (NAC).A quantitative model was employed to predict the CO2 uptake of RAC in this study. The carbonation of RAC and thespecific surface area of recycled coarse aggregates (RCAs) were tested to verify accuracy of the quantitative model. Basedon the verified model, results show that the CO2 uptake capacity increases with the increase of RCA replacementpercentage. The CO2 uptake amount of 1 m^3 C30 RAC within 50 years is 10.6, 13.8, 17.2, and 22.4 kg when the RCAreplacement percentage is 30%, 50%, 70%, and 100%, respectively. The CO2 uptake by RCAs is remarkable and reaches35.8%- 64.3% of the total CO2 uptake by RAC when the RCA storage time being 30 days. Considering the fact that theamount of old hardened cement paste in RCAs is limited, there is an upper limit for the CO2 uptake of RCAs.

关键词： RAC CO2 uptake carbonation specific surface area RCA

热载荷下脆性固体中三维平行内裂纹的相互作用:实验和数值模拟

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Journal of Central South University 2023年第1期30卷 331-350页

作者：汪云飞王海军赵新铭汤雷潘建伍 Department of Civil and airport Engineering Civil Aviation CollegeNanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China

热断裂是一种典型断裂。裂纹广泛存在于脆性固体中,温度变化下裂纹的应力集中与扩展对于热断裂有着重要影响。传统研究大多集中在表面裂纹或二维裂纹,而对于温度场下内裂纹的扩展及多内裂纹的相互作用研究较少。本文使用3D-激光疲劳内裂... 详细信息

热断裂是一种典型断裂。裂纹广泛存在于脆性固体中,温度变化下裂纹的应力集中与扩展对于热断裂有着重要影响。传统研究大多集中在表面裂纹或二维裂纹,而对于温度场下内裂纹的扩展及多内裂纹的相互作用研究较少。本文使用3D-激光疲劳内裂纹(3D-ILC)方法,在完整立方体试件内制作三维双平行内裂纹,对表面不造成任何损伤。开展了温度场下不同垂直间距内裂纹断裂物理试验和三维数值模拟,并对双裂纹相互作用模式进行了分析讨论。结果表明:1)当双裂纹共面时,内裂纹两侧温度场分布对称,双裂纹扩展方向不发生偏移,内裂纹内侧尖端相互吸引最终融合,属于Mode-I型裂纹。此外共面裂纹扩展迹线相交呈“I”形断口特征。2)双裂纹垂直间距d与裂纹半径a之比d/a<2时,双裂纹相互吸引并融合,且当d/a=1时相互作用程度最大,非共面裂纹迹线交并为“月牙形”断口特征。3) d/a≥2后双裂纹内侧尖端扩展呈“排斥”,而“排斥”现象是边界效应导致,并非多裂纹间相互作用,属于Ⅰ-Ⅱ型复合裂纹。4)不论垂直间距大小,内裂纹两侧尖端均存在应力集中现象,且内侧远大于外侧,故内侧裂纹扩展长度大于外侧。研究结果为温度场下三维双平行裂纹相互作用的研究提供了实验和理论依据。

关键词：热断裂 3D激光疲劳内裂纹(3D-ILC) 双裂纹脆性固体裂纹扩展裂纹相互作用

Dynamic Impact Compressive Behavior Investigation of Sisal Fiber-reinforced Coral Seawater Concrete

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Journal of Wuhan University of Technology(Materials Science) 2023年第5期38卷 1034-1043页

作者： MA Haiyan TAN Yongshan YU Hongfa YUE Chengjun ZHANG Yan Department of airport and Civil Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China college of Civil Science and Engineering Yangzhou UniversityYangzhou 225i27China School of Civil Engineering Southeast UniversityNanjing 21118China

Split Hopkinson pressure bar(SHPB)was used to investigate the dynamic compressive properties of sisal fiber reinforced coral aggregate concrete(SFCAC).The results showed that,with the increase of strain rate,the dynamic compressive strength,peak strain and toughness index of SFCAC are all greater than its static properties,indicating that SFCAC is a kind of rate-sensitive material.When the sisal fiber was blended,the failure mode showed obvious ductility.At high strain rates,the SFCAC without sisal fiber specimen was comminuted,and the SFCAC showed a"cracked without breaking"state.The results indicated that the sisal fiber played a significant role in reinforcing and strengthening the properties of concrete.The finite element software LS-DYNA was used to simulate two working conditions with strain rates of 78 and 101 s-1.The stressstrain curves and failure patterns obtained were in good agreement with the experimental results.

关键词： coral aggregate concrete sisal fiber dynamic compressive strain-rate effect

Dynamic Buffering Performance of the Honeycomb Paperboard Filled with Polyurethane

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Journal of Wuhan University of Technology(Materials Science) 2014年第3期29卷 561-566页

作者：张勇 XIE Weihong CHEN Li Mechanics & Architecture Engineering college China University of Mining & Technology Department of airport Engineering Air Force Service College Engineering Institute of Engineering Corps PLA University of Science & Technology

A new kind of composite buffering material was made by filling the voids of honeycomb paperboard with polyurethane. Drop tests were performed to evaluate the dynamic energy absorption capacity of the material. Based on the tests results, we analyzed the mechanical behaviors of the material under different conditions and obtained the inherent influencing laws of some factors on the material＇s dynamic buffering performance. It was shown that the dynamic buffering performance varied directly with impact velocity, and inversely with the void diameter, thickness and buffeting area of the composite material.

关键词： honeycomb paperboard filled with polyurethane drop test energy absorption capacity composite material