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ANALYSIS OF SHEAR LOCALIZATION IN POROUS MATERIALS

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Acta Mechanica Sinica 1990年第1期6卷 29-34页

作者： Sun Yi wang duo, department of applied mechanics, harbin institute of technology 1. department of applied mechanics Harbin Institute of Technology Harbin China

A set of constitutive equations are derived based on the authors'lower bound yield loci for porous materials. By using these equations, the conditions for shear localization in porous materials are then investigated and the results are compared with those of Gurson's equations and the finite element analysis. The advantages of the present constitutive equations are fully illustrated.

关键词： constitutive equations shear localization analysis porous materials ductile fracture

Evaluating the stability and volumetric flowback rate of proppant packs in hydraulic fractures using the lattice Boltzmann-discrete element coupling method

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Journal of Rock mechanics and Geotechnical Engineering 2024年第6期16卷 2052-2063页

作者： duo wang Sanbai Li Rui wang Binhui Li Zhejun Pan National Key Laboratory of Continental Shale Oil Northeast Petroleum UniversityDaqing163318China institute of Unconventional Oil&Gas Northeast Petroleum UniversityDaqing163318China School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen518055China National Center for applied Mathematics Shenzhen(NCAMS) Southern University of Science and TechnologyShenzhen518055China National Key Laboratory of Continental Shale Oil Daqing Oilfield of CNPCDaqing163002China Daqing Oilfield Exploration and Development Research institute DaqingHeilongjiang163712China

The stability and mobility of proppant packs in hydraulic fractures during hydrocarbon production are numerically investigated by the lattice Boltzmann-discrete element coupling method(LB-DEM).This study starts with a preliminary proppant settling test,from which a solid volume fraction of 0.575 is calibrated for the proppant pack in the *** the established workflow to investigate proppant flowback,a displacement is applied to the fracture surfaces to compact the generated proppant pack as well as further mimicking proppant embedment under closure *** a pressure gradient is applied to drive the fluid-particle flow,a critical aperture-to-diameter ratio of 4 is observed,above which the proppant pack would *** results also show that the volumetric proppant flowback rate increases quadratically with the fracture aperture,while a linear variation between the particle flux and the pressure gradient is exhibited for a fixed fracture *** research outcome contributes towards an improved understanding of proppant flowback in hydraulic fractures,which also supports an optimised proppant size selection for hydraulic fracturing operations.

关键词： Numerical simulation Hydraulic fracturing Proppant flowback Closure stress Particulate flow

Effect of the Oxidation Time on Properties of Ceramic Coatings Produced on Ti-6Al-4V by Micro-Arc Oxidation

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维普期刊数据库

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Journal of Materials Science & technology 2005年第2期21卷 281-284页

作者： Zhaohua JIANG, Xuetong SUN, Yanping LI, Fuping wang and Yandong LU department of applied Chemistry, harbin institute of technology, harbin 150001, China Dept. of Appl. Chem. Harbin Inst. of Technol. Harbin 150001 China

Ceramic coatings were prepared on Ti-6AI-4V alloy using ac micro-arc oxidation (MAO) in silicate-hypophosphate solution. Growth regularity and formation mechanism of ceramic coatings were discussed. It was found that during the first stage the growth rate of coatings toward the external surface was larger than that toward substrate and then the coating began to grow mainly towards Ti alloy. When the total coating thickness reaches a certain value, it would no longer increase. In addition, the variations of the composition and microstructure of ceramic coatings according to the depositing time were also investigated with X-ray diffraction (XRD) and scanning electron microscope (SEM). The amount of rutile TiO2 gradually increased, whereas the amounts of the anatase TiO2 and amorphous phases first increased and then decreased slightly.

关键词： Titanium alloy Ceramic coating Oxidation time Thickness

DYNAMIC ANALYSIS OF A BURIED RIGID ELLIPTIC CYLINDER PARTIALLY DEBONDED FROM SURROUNDING MATRIX UNDER SHEAR WAVES

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Acta Mechanica Solida Sinica 1995年第1期8卷 51-63页

作者： wang Yuesheng wang duo, department of Astronautics and mechanics, harbin institute of technology, harbin 150001, P. R. China department of Astronautics and mechanics Harbin Institute of Technology Harbin 150001 China

This paper investigates the dynamic behavior of a buried rigid elliptic cylinder partially debonded from surrounding matrix under the action of anti-plane shear waves (SH waves). The debonding region is modeled as an elliptic arc-shaped interface crack with non-contacting faces. By using the wave function (Mathieu function) expansion method and introducing the dislocation density function as an unknown variable, the problem is reduced to a singular integral equation which is solved numerically to calculate the near and far fields of the problem. The resonance of the structure and the effects of various parameters on the resonance are discussed.

关键词： elastic wave scattering interface debonding interface crack wave function singular integral equation

UNSTEADY SUPERCAVITATING FLOW PAST CONES

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Journal of Hydrodynamics 2006年第3期18卷 262-272页

作者： HU Chao YANG Hong-lan ZHAO Cun-bao HUANG Wen-hu institute of Aerospace Engineering and applied mechanics Tongji Universtity Shanghai 200092 China department of Aerospace Engineering and mechanics Harbin Institute of Technology Harbin 150001 China department of Aerospace Engineering and mechanics Harbin Institute of Technology Harbin 150001 China

Based on integral equation method, the study of unsteady supercavitating flow past cones is presented. The shape and length of supercavity are calculated respectively using the finite difference time discretization method. The characteristics of the shape and length of supercavities, which vary with the cone＇s angle and cavitation number, are investigated respectively, the varied features of some supercavity scales are analyzed when the flow field is perturbed periodically. The curves relationship between cavity length and cavitation number, which are based respectively on present method and other theories, are discussed and compared. It is obviously shown that the supercavity changes have two characteristics： retardance and wave. These results obtained would be useful in the case of design and analysis of cavitator under water.

关键词： supercavitation cavitator unsteady flow,slender body theory integral equation method

Three-dimensional configurations of organic/inorganic hybrid nanostructural blocks (I).A quantum mechanical investigation for ladder-like structure of vinylsilsesquioxane

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Science China Chemistry 2004年第5期47卷 388-395页

作者： ZHANG Xingwen1,2, HU Lijiang1, HUANG Yudong1, SUN Dezhi2 & SUN Yi3 1. department of applied Chemistry,harbin institute of technology, HUANG Yudong, harbin 150001, China 2. department of Environmental Engineering, harbin institute of technology, harbin 150001, China 3. department of Experimental mechanics,harbin institute of technology, harbin 150001, China 1. department of applied Chemistry Harbin Institute of Technology HUANG Yudong 150001 Harbin China 2. department of Environmental Engineering Harbin Institute of Technology 150001 Harbin China 3. department of Experimental mechanics Harbin Institute of Technology 150001 Harbin China

The organic/inorganic hybrid nanostructural vinylsilsesquioxanes (VSSO) were prepared from the hydrolytic condensation of vinyltrimethoxysilane (VMS). The proposed formu- las of VSSO were assigned with standard spectroscopic techniques, FTIR, NMR (1H, C and 13 29Si) and MALDI-TOF MS, and a generic formula of the SSO, Tn(OH)x(OR’)y(x, y = 0, 1, 2…; n = 1, 2…; T = RSiO1.5 ?(x+y)/2n). Geometric parameters (Si-O and Si-C bond lengths, Si-O-Si and O-Si-O bond angles) and total energies of the multi-structures of VSSO were calculated by a quantum mechanical investigation and molecular symmetries. According to the results of the calculation, most molecules had stabler ladder structures than the cage isomers, therefore, the most probably reasonable and optimum structure of the VSSO system was the ladder type.

关键词： vinyltrimethoxysilane (VMS), silsesquioxanes (SSO), sol-gel process, quantum mechanical calculation, MNDO.

DYNAMIC STRESS CONCENTRATIONS IN AMBARTSUMIAN'S PLATE WITH A CUTOUT

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Acta Mechanica Solida Sinica 1998年第4期11卷 341-350页

作者： Hu Chao Zhao Xinghua (institute of applied Mathematics and mechanics,Shanghai University,Shanghai 200072,China)Ma Xingrui Huang Wenhu (harbin institute of technology,harbin 150001,China) Shanghai Univ Inst Appl Math & Mech Shanghai 200072 Peoples R China harbin Inst Technol Harbin 150001 Peoples R China

Based on the motion equations of flexural wave in Ambartsumian' s plates including the effects of transverse shear deformations,by using perturbation method of small parameter,the scatter- ing of flexural waves and dynamic stress concentrations in the plate with a cutout have been studied. The asypmtotic solution of the dynamic stress problem is *** results for the dynamic stress concentration factor in Ambartsumian's plates with a circular cutout are graphically presented and discussed.

关键词： Ambartsumian's plate cutout dynamic stress concentration perturbation method

Study on the Effects of End-bend Cantilevered Stator in a 2-stage Axial Compressor

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Journal of Thermal Science 2009年第2期18卷 119-125页

作者： Songtao wang Xin DU Zhongqi wang harbin institute of technology, P.O. BOX 458, harbin 150001, China harbin institute of technology P.O. BOX 458 Harbin 150001 China

Leading edge recambering is applied to the cantilevered stator vanes in a 2-stage compressor in this paper. Differentcurving effects are produced when the end-bend stator vanes are stacked in different ways. Stacking on theleading edge induces a positive curving effect near the *** it is stacked on the centre of gravity, a negativecurving effect takes place. The numerical investigation shows that the flow field is redistributed when theend-bend stators with leading edge stacking are applied. The variations in the stage matching for the mainstreamand near the hub have an impact on the performance of the 2-stage compressor. The isentropic efficiency and thetotal pressure ratio of the compressor are increased near the design condition. The compressor total pressure ratiois decreased near choke and near stall. The maximum flow rate is reduced and the stall margin is decreased.

关键词： axial compressor end-bend blade stacking stage matching

SIMULATION OF THE OIL SLICK MOVEMENT IN TIDAL WATER-WAYS

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Journal of Hydrodynamics 2010年第1期22卷 96-102页

作者： WUZhao-chun wang Dao-zeng Shanghai institute of applied Mathematics and mechanics Shanghai University Shanghai 200072 China School of Construction and Safety Engineering Shanghai Institute of Technology Shanghai 200235 China

Based on particle approach and tidal flow model this article studies the behavior of the oil slick on the water surface in the Huangpu River, a tidal waterway in Shanghai. In order to track the oil slick motion, a two-dimensional oil trajectory model is used. The dynamical properties of spilled oil characterized by advection, oil spreading and turbulent diffusion are considered in the model. The simulation results consistent with the flume experimental data show that the model is applicable. Both simulation and experiment illustrate that the tidal flow has a great influence on the oil slick motion. The calculated results can be used as a reference for the response to oil spill accidents in rivers.

关键词： particle approach track of oil slick numerical simulation