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Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene

KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 76-80 doi: 10.1007/s11705-007-0016-6

摘要： To improve the performance of traditional nucleation additives and their compatibility with other additives, as well as to solve complex problems in practical applications, SiO precursors were reactively grafted in situ with the symmetrical hydroxyl groups of the nucleation agents. With this approach, the dissymmetrical part of the nucleation agents plays an important role. As a result, the prepared composite additive the nanoparticle precursor (NPP0) produces excellent results. The NPP0-PP composite has a transparency of over 93%, haze lower than 15%, and a heat distortion temperature (HDT) of 142?C, which is more than the 110?C of the pure PP matrix. In addition, it maintains over 90% of the mechanical properties with a deformation coefficient less than 1%. This indicates a strong nanoeffect.

关键词： deformation coefficient     distortion temperature     excellent     NPP0-PP     traditional nucleation    

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Resistance of large deformation of the Wushaoling Tunnel F7 soft fault

ZHAO Xufeng, CHEN Haiming, WANG Chunmiao

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 123-127 doi: 10.1007/s11709-007-0013-3

摘要： In this article, the mechanical characteristics of the squeeze of the F7 fault of the Wushaoling Tunnel are analyzed. The measurements and techniques are proposed to resist the deformation. The result indicates that the method of construction to control the further squeeze deflection is appropriate.

关键词： F7     deformation     appropriate     construction     mechanical    

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Numerical modeling of nonlinear deformation of polymer composites based on hyperelastic constitutive

Qingsheng YANG, Fang XU

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 284-288 doi: 10.1007/s11465-009-0067-0

摘要： Fiber reinforced polymer (FRP) composites exhibit nonlinear and hyperelastic characteristics under finite deformation. This paper investigates the macroscopic hyperelastic behavior of fiber reinforced polymer composites using a micromechanical model and finite deformation theory based on the hyperelastic constitutive law. The local stress and deformation of a representative volume element are calculated by the nonlinear finite element method. Then, an averaging procedure is used to find the homogenized stress and strain, and the macroscopic stress-strain curves are obtained. Numerical examples are given to demonstrate hyperelastic behavior and deformation of the composites, and the effects of the distribution pattern of fibers are also investigated to model the mechanical behavior of FRP composites.

关键词： composites     hyperelastic     finite deformation     homogenization     micromechanics    

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RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2161-2161 doi: 10.1007/s11705-009-0143-3

摘要： RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

关键词： tee junction     Momentum exchange coefficient     RETRACTED    

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A continuous/discontinuous deformation analysis (CDDA) method based on deformable blocks for fracture

Yongchang CAI, Hehua ZHU, Xiaoying ZHUANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 369-378 doi: 10.1007/s11709-013-0222-x

摘要： In the framework of finite element meshes, a novel continuous/discontinuous deformation analysis (CDDA) method is proposed in this paper for modeling of crack problems. In the present CDDA, simple polynomial interpolations are defined at the deformable block elements, and a link element is employed to connect the adjacent block elements. The CDDA is particularly suitable for modeling the fracture propagation because the switch from continuous deformation analysis to discontinuous deformation analysis is natural and convenient without additional procedures. The SIFs (stress intensity factors) for various types of cracks, such as kinked cracks or curved cracks, can be easily computed in the CDDA by using the virtual crack extension technique (VCET). Both the formulation and implementation of the VCET in CDDA are simple and straightforward. Numerical examples indicate that the present CDDA can obtain high accuracy in SIF results with simple polynomial interpolations and insensitive to mesh sizes, and can automatically simulate the crack propagation without degrading accuracy.

关键词： fracture     crack     propagation     deformable block     continuous/discontinuous deformation analysis (CDDA)    

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Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 316-324 doi: 10.1007/s11709-013-0211-0

摘要： Three groups of concrete beams reinforced with high-strength steel bars were tested, and the crack width and deformation of the specimens were observed and studied. To facilitate the predictions, two simplified formulations according to a theory developed by the first author were proposed. The advantages of the formulations were verified by the test data and compared with several formulas in different codes.

关键词： concrete beam     high-strength steel bar     crack width     deformation    

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Calculation method of radial stress and deformation on conic threaded connections with interference fit

Shoujun CHEN, Qiang LI, Qi AN,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 302-307 doi: 10.1007/s11465-010-0018-9

摘要： This paper presents a calculation method for radial stress distribution and deformation on conic threaded connections with interference fit. Based on elastic mechanics, a new calculation model is established using the thick-walled-cylindrical theory. A sample calculation for API 88.9 mm conic threaded connection indicates that the method proposed in this paper is reasonable, and the finite element analysis (FEA) method is used to validate the proposed method. The results obtained by the proposed method and FEA method are identical. The model offers a new way of calculating the radial stress and deformation on conic thread connections with interference fit.

关键词： conic threaded connections     interference fit     radial stress     deformation     finite element analysis (FEA)    

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Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 223-232 doi: 10.1007/s11709-010-0022-5

摘要： Rock blasting is a dynamic process accompanied with the propagations of shock waves and the dispersion of the explosion gas. This paper adopts the discontinuous deformation analysis (DDA) method to simulate the rock blasting process. A dynamic parameter adjustment and the non-reflecting boundary condition are implemented in the DDA method. The sub-block DDA method to simulate fracture problems is used. The blasting process in jointed rock mass is simulated by application of the explosion gas pressure on the expanding borehole walls and induced connected fracture surfaces around the boreholes. The blast craters with different overburdens are derived. The whole process including the explosion gas dispersion, borehole expansion, rock mass failure and cast, and the formation of the final blasting piles in rock blasting are well reproduced numerically. Parametric study for different overburdens is carried out, and the results are analyzed and discussed.

关键词： blast crater     jointed rock mass     explosion gas pressure     discontinuous deformation analysis (DDA) method    

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Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1036-1053 doi: 10.1007/s11709-019-0535-5

摘要： Numerical manifold method (NMM) is an effective method for simulating block system, however, significant errors are found in its simulation of rotation problems. Three kinds of errors, as volume expansion, stress vibration, and attenuation of angular velocity, were observed in the original NMM. The first two kind errors are owing to the small deformation assumption and the last one is due to the numerical damping. A large deformation NMM is proposed based on large deformation theory. In this method, the governing equation is derived using Green strain, the large deformation iteration and the open-close iteration are combined, and an updating strategy is proposed. The proposed method is used to analyze block rotation, beam bending, and rock falling problems and the results prove that all three kinds of errors are eliminated in this method.

关键词： numerical manifold method     rotation     large deformation     Green strain     open-close iteration    

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Deformation control criterion of shield tunnel under lateral relaxation of soft soil

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 780-795 doi: 10.1007/s11709-023-0944-3

摘要： Metro shield tunnels under the lateral relaxation of soil (LRS) are susceptible to significant lateral deformations, which jeopardizes the structural safety and waterproofing. However, deformation control standards for such situations have not been clearly defined. Therefore, based on a specific case, a model test is conducted to realize the LRS of a shield tunnel in a sandy stratum to reveal its effect on segment liners. Subsequently, a deformation control criterion is established. The LRS is simulated by linearly reducing the loads applied to the lateral sides of the segment structure. During lateral unloading, the lateral earth pressure coefficient on the segment decreases almost exponentially, and the structural deformation is characterized by horizontal expansion at the arch haunches and vertical shrinkage at the arch vault and arch bottom. Based on the mechanical pattern of the segment structure and the acoustic emission, the deformation response of a segment can be classified into three stages: elastic and quasi-elastic, damage, and rapid deformation development. For a shield tunnel with a diameter of approximately 6 m and under the lateral relaxation of sandy soil, when the ellipticity of the segment is less than 2.71%, reinforcement measures are not required. However, the segment deformation must be controlled when the ellipticity is 2.71% to 3.12%; in this regard, an ellipticity of 3% can be used as a benchmark in similar engineering projects.

关键词： shield tunnel     lateral relaxation of soil     deformation control criterion of segment structure     model test    

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Deformation field and crack analyses of concrete using digital image correlation method

Yijie HUANG, Xujia HE, Qing WANG, Jianzhuang XIAO

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1183-1199 doi: 10.1007/s11709-019-0545-3

摘要： The study on the deformation distribution and crack propagation of concrete under axial compression was conducted by the digital image correlation (DIC) method. The main parameter in this test is the water-cement ( / ) ratio. The novel analysis process and numerical program for DIC method were established. The displacements and strains of coarse aggregate, and cement mortar and interface transition zone (ITZ) were obtained and verified by experimental results. It was found that the axial displacement distributed non-uniformly during the loading stage, and the axial displacements of ITZs and cement mortar were larger than that of coarse aggregates before the occurrence of macro-cracks. The effect of / on the horizontal displacement was not obvious. Test results also showed that the transverse and shear deformation concentration areas (DCAs) were formed when stress reached 30%–40% of the peak stress. The transverse and shear DCAs crossed the cement mortar, and ITZs and coarse aggregates. However, the axial DCA mainly surrounded the coarse aggregate. Generally, the higher / was, the more size and number of DCAs were. The crack propagations of specimens varied with the variation of / . The micro-crack of concrete mainly initiated in the ITZs, irrespective of the / . The number and distribution range of cracks in concrete with high / were larger than those of cracks in specimen adopting low / . However, the value and width of cracks in high / specimen were relatively small. The / had an obvious effect on the characteristics of concrete deterioration. Finally, the characteristics of crack was also evaluated by comparing the calculated results.

关键词： deformation filed distribution     crack development     digital image correlation method     mechanical properties     water-cement ratio     characteristics of deformation and crack    

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Experimental study of heat transfer coefficient with rectangular baffle fin of solar air heater

Foued CHABANE,Nesrine HATRAF,Noureddine MOUMMI

《能源前沿（英文）》 2014年 第8卷 第2期   页码 160-172 doi: 10.1007/s11708-014-0321-y

摘要： This paper presents an experimental analysis of a single pass solar air collector with, and without using baffle fin. The heat transfer coefficient between the absorber plate and air can be considerably increased by using artificial roughness on the bottom plate and under the absorber plate of a solar air heater duct. An experimental study has been conducted to investigate the effect of roughness and operating parameters on heat transfer. The investigation has covered the range of Reynolds number from 1259 to 2517 depending on types of the configuration of the solar collectors. Based on the experimental data, values of Nusselt number have been determined for different values of configurations and operating parameters. To determine the enhancement in heat transfer and increment in thermal efficiency, the values of Nusselt have been compared with those of smooth duct under similar flow conditions.

关键词： Nusselt number     flow rate     heat transfer     heat transfer coefficient     thermal efficiency     forced convection    

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Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation

Mohammad Javad REZVANIL, Mohammad Hossein KARGARNOVIN, Davood YOUNESIAN

《机械工程前沿（英文）》 2011年 第6卷 第4期   页码 409-418 doi: 10.1007/s11465-011-0245-8

摘要：

The response of an infinite Timoshenko beam subjected to a harmonic moving load based on the third-order shear deformation theory (TSDT) is studied. The beam is made of laminated composite, and located on a Pasternak viscoelastic foundation. By using the principle of total minimum potential energy, the governing partial differential equations of motion are obtained. The solution is directed to compute the deflection and bending moment distribution along the length of the beam. Also, the effects of two types of composite materials, stiffness and shear layer viscosity coefficients of foundation, velocity and frequency of the moving load over the beam response are studied. In order to demonstrate the accuracy of the present method, the results TSDT are compared with the previously obtained results based on first-order shear deformation theory, with which good agreements are observed.

关键词： timoshenko composite beam     pasternak viscoelastic foundation     third-order shear deformation theory (TSDT)     harmonic moving load    

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A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

David R. HOKANSON,Ke LI,R. Rhodes TRUSSELL

《环境科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 428-437 doi: 10.1007/s11783-015-0780-3

摘要： UV photolysis and UV based advanced oxidation processes (AOPs) are gaining more and more attention for drinking water treatment. Quantum yield ( ) and molar absorption coefficient ( ) are the two critical parameters measuring the effectiveness of photolysis of a compound. The product of the two was proposed as a fundamental measure of a constituent’s amenability to transformation by photolysis. It was shown that this product, named the photolysis coefficient, , can be determined using standard bench tests and captures the properties that govern a constituent’s transformation when exposed to light. The development showed the photolysis coefficient to be equally useful for microbiological, inorganic and organic constituents. Values of calculated by the authors based on quantum yield and molar absorption coefficient data from the literature were summarized. Photolysis coefficients among microorganisms ranged from 8500 to more than 600000 and are far higher than for inorganic and organic compounds, which varied over a range of approximately 10 to 1000 and are much less sensitive to UV photolysis than the microorganisms.

关键词： UV photolysis     disinfection     advanced oxidation     N-nitrosodimethylamine     quantum yield     absorption coefficient    

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Seismic effects on reinforcement load and lateral deformation of geosynthetic-reinforced soil walls

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 1001-1015 doi: 10.1007/s11709-021-0734-8

摘要： Current design methods for the internal stability of geosynthetic-reinforced soil (GRS) walls postulate seismic forces as inertial forces, leading to pseudo-static analyses based on active earth pressure theory, which yields unconservative reinforcement loads required for seismic stability. Most seismic analyses are limited to the determination of maximum reinforcement strength. This study aimed to calculate the distribution of the reinforcement load and connection strength required for each layer of the seismic GRS wall. Using the top-down procedure involves all of the possible failure surfaces for the seismic analyses of the GRS wall and then obtains the reinforcement load distribution for the limit state. The distributions are used to determine the required connection strength and to approximately assess the facing lateral deformation. For sufficient pullout resistance to be provided by each reinforcement, the maximum required tensile resistance is identical to the results based on the Mononobe–Okabe method. However, short reinforcement results in greater tensile resistances in the mid and lower layers as evinced by compound failure frequently occurring in GRS walls during an earthquake. Parametric studies involving backfill friction angle, reinforcement length, vertical seismic acceleration, and secondary reinforcement are conducted to investigate seismic impacts on the stability and lateral deformation of GRS walls.

关键词： geosynthetics     reinforced soil     retaining walls     seismic performance    

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标题 作者 时间 类型 操作

Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene

KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu

期刊论文

Resistance of large deformation of the Wushaoling Tunnel F7 soft fault

ZHAO Xufeng, CHEN Haiming, WANG Chunmiao

期刊论文

Numerical modeling of nonlinear deformation of polymer composites based on hyperelastic constitutive

Qingsheng YANG, Fang XU

期刊论文

RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

期刊论文

A continuous/discontinuous deformation analysis (CDDA) method based on deformable blocks for fracture

Yongchang CAI, Hehua ZHU, Xiaoying ZHUANG

期刊论文

Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

期刊论文

Calculation method of radial stress and deformation on conic threaded connections with interference fit

Shoujun CHEN, Qiang LI, Qi AN,

期刊论文

Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

期刊论文

Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

期刊论文

Deformation control criterion of shield tunnel under lateral relaxation of soft soil

期刊论文

Deformation field and crack analyses of concrete using digital image correlation method

Yijie HUANG, Xujia HE, Qing WANG, Jianzhuang XIAO

期刊论文

Experimental study of heat transfer coefficient with rectangular baffle fin of solar air heater

Foued CHABANE,Nesrine HATRAF,Noureddine MOUMMI

期刊论文

Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation

Mohammad Javad REZVANIL, Mohammad Hossein KARGARNOVIN, Davood YOUNESIAN

期刊论文

A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

David R. HOKANSON,Ke LI,R. Rhodes TRUSSELL

期刊论文

Seismic effects on reinforcement load and lateral deformation of geosynthetic-reinforced soil walls

期刊论文