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Underground Space 2020年第2期5卷 125-143页

作者： Xiangrong Wang Department of civil and Environmental engineering and engineering Mechanics The University of DaytonDaytonOH 45469-0243USA

Subsurface stratigraphy is critical to the design,construction,and subsequent performance of geotechnical ***,in practice it is impossible to identify the stratigraphy of a subsurface geological domain with absolute certainty,due to the limitations imposed by geotechnical investigation techniques and project *** paper presents a subsurface stratigraphic modeling and uncertainty quantification approach,which is established based on an improved and extended geological modeling technique previously established by the author and others,for simulating the stratigraphy of both two-dimensional(2D)and three-dimensional(3D)cases with more complex geological ***,this approach provides quantitative evaluation of the amount of stratigraphic uncertainty in the current interpretation and enables the systematic reduction of stratigraphic uncertainty through the investigation of additional targeted borehole drilling *** examples,including artificial cases as well as two real cases from existing geotechnical projects,are presented in this study to demonstrate the use of the proposed analysis approach.

关键词： Site investigation Stratigraphy Stochastic modeling Uncertainty quantification Borehole drilling

PARAMETRIC IDENTIFICATION AND SENSITIVITY ANALYSIS FOR AUTONOMOUS UNDERWATER VEHICLES IN DIVING PLANE

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Journal of Hydrodynamics 2012年第5期24卷 744-751页

作者： XU Feng ZOU Zao-jian YIN Jian-chuan CAO Jian School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240China School of Naval Architecture Ocean and Civil Engineering and State Key Laboratory of Ocean EngineeringShanghai Jiao Tong University Shanghai 200240 China College of Shipbuilding engineering Harbin Engineering University Harbin 150001 China

The inherent strongly nonlinear and coupling performance of the Autonomous Underwater Vehicles （AUV）, maneuvering motion in the diving plane determines its difficulty in parametric identification. The motion parameters in diving plane are obtained by executing the Zigzag-like motion based on a mathematical model of maneuvering motion. A separate identification method is put forward for parametric identification by investigating the motion equations. Support vector machine is proposed to estimate the hydrodynamic derivatives by analyzing the data of surge, heave and pitch motions. Compared with the standard coefficients, the identified parameters show the validation of the proposed identification method. Sensitivity analysis based on numerical simulation demonstrates that poor sensitive derivative gives bad estimation results. Finally the motion simulation is implemented based on the dominant sensitive derivatives to verify the reconstructed model.

关键词： parametric identification Autonomous Underwater Vehicles (AUVs) support vector machine sensitivity analysis

Electric admittance analysis of quartz crystal resonator in thickness-shear mode induced by array of surface viscoelastic micro-beams

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Applied Mathematics and Mechanics(English Edition) 2017年第1期38卷 29-38页

作者： Jiemin XIE Yuantai HU School of civil engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China

The electric admittance of a compound system composed of a thickness-shear mode （TSM） quartz crystal resonator （QCR） and an array of surface viscoelastic micro-beams （MBs） is studied. The governing equations of the MBs are derived from the Timoshenko-beam theory in consideration of shear deformation. The electrical admittance is described directly in terms of the physical properties of the surface epoxy resin （SU-8） MBs from an electrically forced vibration analysis. It is found that both the inertia effect and the constraint effect of the MBs produce competitive influence on the resonant frequency and admittance of the compound QCR system. By further comparing the numerical results calculated from the Timoshenko-beam model with those from the Euler-beam model, the shear deformation is found to lead to some deviation of an admittance spectrum. The deviations are revealed to be evident around the admittance peak（s） and reach the maximum when a natural frequency of the MBs is identical to the fundamental frequency of the QCR. Besides, a higher order vibration mode of the MBs corresponds to a larger deviation at the resonance.

关键词： quartz crystal resonator (QCR) thickness-shear mode (TSM) electrical admittance shear deformation

A comparative study of wave localization in locally resonant Thue–Morse, Rudin–Shapiro and Period-Doubling aperiodic structures

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Acta Mechanica Solida Sinica 2017年第3期30卷 271-284页

作者： Zhizhong Yan Yangyang Wang Chuanzeng Zhang School of Mathematics and Statistics Beijing Institute of Technology Department of civil engineering University of Siegen

The localization characteristics of the in-plane elastic waves in locally resonant aperiodic phononic crystals are examined in this study. In particular, the phononic crystals generated according to the Thue-Morse, Rudin-Shapiro and Period-Doubling sequences are theoretically investigated by using the extended transfer matrix method. For comparison, the binary and ternary locally resonant systems are considered, and their band structures are characterized by using the localization factors. Moreover, the influences of structural arrangement, material combination, incidence angle, number of components, length ratio, and random disorder on the band structures are also discussed. Some novel and interesting phenomena are observed and discussed.

关键词： Phononic crystals Aperiodicity Wave localization Localization factor Transfer matrix method

Durability Properties of Materials and Mixture Composition of Bitumen Stabilized Materials

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武汉理工大学学报 2010年第17期32卷 215-226页

作者： TWAGIRA M E JENKINS J K Dept of civil engineering Stellenbosch University

Bitumen Stabilized Materials (BSMs) are widely recognized as environmentally friendly through significantly reduced energy consumption,reduced emissions and reuse of high percentage of RAP and recycled pavement materials. In order for these materials to be cost effective,their life-cycle performance needs to be proven. Durability of BSMs is a long-term phenomena that requires consideration during mix design. Time is very important variable for performance consideration under field conditions. The factors that influence durability and long-term performance of BSMs include the mineral aggregates,binder and mixture compositions. In this study,the important,but less understood aspects of durability properties of BSMs were investigated. These include wear and tear of mineral aggregates,age-hardening of binder (foamed bitumen and bitumen emulsion) and moisture susceptibility of typical mix composition. The wear and tear was investigated using Durability Mill Index (DMI) test,binder ageing was investigated for short and long-term effect,and moisture susceptibility was investigated by pulsing water pressures using new device i.e. moisture induction simulation test (MIST). The accelerated moisture conditioning simulates field conditions whereafter retained shear properties are evaluated. The results found that durability of mineral aggregates is significantly influences by the type and nature of mineral composition. The ageing of binder occurred in both short and long-term conditions,with short-term effects being dominating the foamed bitumen properties during laboratory production. Moisture susceptibility is significantly influenced by the mix compositions of aggregates blends with and without RAP,with different bitumen binder types (foamed bitumen or bitumen emulsion) and active filler type (cement or lime) and contents. The evaluation and ranking of mixes which are resistant and susceptible to moisture damage was done using retained cohesion (RC) after dry and wet monoton

关键词： durability properties bitumen stabilized materials moisture susceptibility ageing

FINITE ELEMENT ANALYSIS ON EVOLUTION PROCESS FOR DAMAGE MICROCRACK HEALING

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Acta Mechanica Sinica 2000年第3期16卷 254-263页

作者：黄佩珍李中华孙军 School of civil engineering and Mechanics Xi'an Jiaotong UniversityXi'an 710049China School of Civil Engineering and MechanicsShanghai Jiaotong UniversityShanghai 200240China School of civil engineering and Mechanics Shanghai Jiaotong UniversityShanghai 200240China State Key Laboratory for Mechanical Behaviour of Materials Xi'an diaotong UniversityXi'an 710049China

Based on the thermal kinetic and mass conservation, a series of controlling equations for the finite element are derived and related programs are developed to simulate the damage microcrack healing process controlled by surface diffusion. Two kinds of typical models for microcrack splitting are proposed, i.e., the grain boundary energy existing on the crack surface and residual stresses applying on the crack surface. And the conditions of microcrack splitting in the two models are given as a function of the microcrack aspect ratio. The microcrack with traction-free surfaces will directly evolve into a spheroid.

关键词： microcrack damage healing microcrack splitting and spheroidization surface diffusion finite element method

Thermo-mechanical simulation of frost heave in saturated soils

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Frontiers of Structural and civil engineering 2023年第9期17卷 1400-1412页

作者： Saeed VOSOUGHIAN Romain BALIEU Department of civil and Architectural engineering KTH Royal Institute of TechnologyStockholm 10044Sweden

Roads are exposed to various degradation mechanisms during their *** pavement deterioration caused by the surrounding environment is particularly severe in winter when the humidity and subfreezing temperatures *** heave-induced damage is one of the winter-related pavement *** occurs when the porewater in the soil is exposed to freezing *** study of frost heave requires conducting a multiphysics analysis,considering the thermal,mechanical,and hydraulic *** paper presents the use of a coupled thermo-mechanical approach to simulate frost heave in saturated soils.A function predicting porosity evolution is implemented to couple the thermal and mechanical field *** function indirectly considers the effect of the water seepage inside the *** frost heave scenarios with uniform and non-uniform boundary conditions are considered to demonstrate the capabilities of the *** results of the simulations indicate that the thermo-mechanical model captures various processes involved in the frost heave phenomenon,such as water fusion,porosity variation,cryogenic suction force generation,and soil *** characteristics and consequences of each process are determined and discussed ***,the results show that non-uniform thermal boundaries and presence of a culvert inside the soil result in uneven ground surface deformations.

关键词： frost heave multiphysics analysis thermo-mechanical approach saturated soils

Experimental Investigation on the Vibration Attenuation of Tensegrity Prisms Integrated with Particle Dampers

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Acta Mechanica Solida Sinica 2022年第4期35卷 672-681页

作者： Si-Qi An Hao-Ran Zou Wen-Hao Li Zi-Chen Deng School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China

Tensegrities made of tensile strings and compressed struts possess large strength-to-mass ratio values but tend to experience non-negligible vibration in dynamic environments because of poor structural ***,we introduce particle dampers into a tensegrity prism to attenuate vibration,with the goal of establishing a lightweight and efficient approach of vibration *** integrate the particle dampers and the tensegrity,a novel strut structure formed by assembling a solid strut and a hollow strut is devised,in which granular materials are inserted to develop a particle *** vibration attenuation performance of the tensegrity prism is investigated through exciter *** to the experimental parametric study,the influences of system parameters including excitation magnitude,the filling height of particles,particle size and the configuration of tensegrity prism on the vibration attenuation performance is *** addition,the experimental results regarding the dependence of the vibration attenuation on the system parameters are interpreted by the mechanism of collisions and frictions between particles and between particles and *** maximal vibration attenuation ratio of 76%can be achieved in the ***,this research can provide insights into the design of lightweight tensegrity structures where vibration suppression is important,particularly in some dynamic environments.

关键词： Tensegrity structures Particle dampers Vibration suppression Assembling struts

Micromorphology and safety properties of meager and meager-lean coal for blast furnace injection

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 774-781页

作者： Long-zhe Jin Xiao-meng Niu School of civil and Resource engineering University of Science and Technology BeijingBeijing 100083China

Four types of meager and meager-lean coal and one type of high-quality anthracite were selected based on the safety requirements for blast furnace coal injection and domestic coal quality to conduct microstructure and component *** analyses of the organic and inorganic macerals and the chemical compositions of the selected coal samples indicate that the four types of meager and meager-lean coal have low volatilization,low ash content,and low sulfur content;these qualities are suitable for blast furnace *** test was conducted on the four types of meager and meager-lean coal and the anthracite mixed coal *** indicate that the mixture of meager and meager-lean coal and anthracite is beneficial to improve the grindability of pulverized *** explosive tests reveal that the selected coal samples are non-explosive or weakly *** the proportion of meager and meager-lean coal is less than 40wt%,the mixed coal powder would not explode during the blowing *** minimum ignition temperature test determines that the minimum ignition temperatures of the four types of meager and meager-lean coal and anthracite are 326,313,310,315,and 393°C,*** study provides a guiding research idea for the safety of meager and meager-lean coal used in blast furnace injection.

关键词： meager coal meager-lean coal microstructure safety property blast furnace injection

Effects of Strain Rate,Temperature and Grain Size on the Mechanical Properties and Microstructure Evolutions of Polycrystalline Nickel Nanowires:A Molecular Dynamics Simulation

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Wuhan University Journal of Natural Sciences 2018年第3期23卷 251-258页

作者： RUAN Zhigang WU Wenping LI Nanlin School of civil engineering Wuhan University

Through molecular dynamics（MD） simulation, the dependencies of temperature, grain size and strain rate on the mechanical properties were studied. The simulation results demonstrated that the strain rate from 0.05 to 2 ns–1 affected the Young＇s modulus of nickel nanowires slightly, whereas the yield stress increased. The Young＇s modulus decreased approximately linearly; however, the yield stress firstly increased and subsequently dropped as the temperature increased. The Young＇s modulus and yield stress increased as the mean grain size increased from 2.66 to 6.72 nm. Moreover, certain efforts have been made in the microstructure evolution with mechanical properties association under uniaxial tension. Certain phenomena such as the formation of twin structures, which were found in nanowires with larger grain size at higher strain rate and lower temperature, as well as the movement of grain boundaries and dislocation, were detected and discussed in detail. The results demonstrated that the plastic deformation was mainly accommodated by the motion of grain boundaries for smaller grain size. However, for larger grain size, the formations of stacking faults and twins were the main mechanisms of plastic deformation in the polycrystalline nickel nanowire.

关键词： Effects of Strain Rate Temperature and Grain Size on the Mechanical Properties and Microstructure Evolutions of Polycrystalline Nickel Nanowires A Molecular Dynamics Simulation