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Experimental study of CT test on the failure of acrylate spray-applied waterproof layer in the groundwater environment

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Science china(Technological Sciences) 2010年第2期53卷 512-518页

作者： YANG QiXin, XU Peng & ZHENG ShangFeng 1 school of civil engineering, Southwest jiaotong University, Chengdu 610031, china school of civil engineering Southwest Jiaotong University Chengdu China

In this study the computerized tomography (CT) was first used to quantitatively analyze the failure of acrylate spray-applied waterproof membrane in the groundwater environment. The results of the CT tests show that it is feasible to use the CT to quantitatively analyze the failure of the waterproof membrane and the CT method has the advantages of speediness and accuracy that can eliminate the fussy operation process in routine tests. The main conclusions summarized from the study are as follows. First, there are two combined-indexes that can be used to decide the failure of the spray-on waterproof layer: one is that the reduced percentage of the CT number of the spray-on waterproof layer is less than 40.0% and the other is that the variance of the CT number decreases first and then increases. Second, the applicability for the spray-on waterproof layer in the groundwater environment is the SO 24-concentration ≤ 1%, the Cl-concentration ≤ 7.5% and the pH value ≤ 12.0 of the groundwater, respectively.

关键词： spray-on waterproof layer scan CT number failure groundwater environment

MOLECULAR DYNAMICS SIMULATION OF INTERFACIAL DEFECTS WITH MODIFIED POTENTIAL BASED ON THE FIRST-PRINCIPLE

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Acta Mechanica Solida Sinica 2010年第5期23卷 400-406页

作者： Dongwei Ren Jinquan Xu 1(school of Naval Architecture and civil engineering,Shanghai jiaotong University,Shanghai 200240,china) school of Naval Architecture and civil engineering Shanghai Jiaotong University Shanghai China

The interfacial molecular structure of materials with different lattice constants is simulated by using the method of molecular dynamics （MD）. Potential of modified analytical embedded atom method （MAEAM） is used for nominterfacial atoms. To simulate the state of interracial atoms, further modifications are applied to the MAEAM potential based on the first- principle simulation results. It is concluded that a small change of potential may greatly influence the interfacial molecular structure. Void and diffusions can be observed in the simulation results. It is also found that the pre-existed dot defects before bonding can decrease the number of interfacial defects greatly, thereby, can increase the strength of the interface.

关键词： molecular dynamics interface defect potential first-principle

A geometrical and physical nonlinear finite element model for spatial thin-walled beams with arbitrary section

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Science china(Technological Sciences) 2010年第3期53卷 829-838页

作者： YANG QingShan 1 &WANG XiaoFeng 2 1 school of civil engineering,Beijing jiaotong University,Beijing 100044,china 2 College of civil engineering,Tongji University,Shanghai 200092,china school of civil engineering Beijing Jiaotong University Beijing China College of civil engineering Tongji University Shanghai China

Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all ***,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are *** plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of *** stiffness matrix is derived by numerical integration on the basis of the finite segment *** show that the developed model is feasible in analysis of thin-walled structures with high accuracy.

关键词： Spatial beams thin-walled structures geometrical and physical nonlinearity finite element arbitrary section

Advances in numerical methods for the solution of population balance equations for disperse phase systems

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Science china Chemistry 2009年第8期52卷 1063-1079页

作者： SU JunWei1,GU ZhaoLin2,3 & XU X.Yun41 Department of Mechanical engineering and Automation,school of Mechanical engineering,Xi’an jiaotong University,Xi’an 710049,china 2 Key Laboratory of Mechanics on Disaster and Environment in Western china,Ministry of Education,lanzhou 730000,china 3 Department of Environmental Science and Technology,school of Human Settlements and civil engineering,Xi’an jiaotong University,Xi’an 710049,china 4 Department of Chemical engineering,Imperial College London,London SW7 2AZ,UK Department of Mechanical engineering and Automation School of Mechanical Engineering Xi’an Jiaotong University Xi’an China Key Laboratory of Mechanics on Disaster and Environment in Western china Ministry of Education Lanzhou China Department of Environmental Science and Technology School of Human Settlements and Civil Engineering Xi’an Jiaotong University Xi’an China Department of Chemical engineering Imperial College London London UK

Accurate prediction of the evolution of particle size distribution is critical to determining the dynamic flow structure of a disperse phase system.A population balance equation(PBE),a non-linear hyperbolic equation of the number density function,is usually employed to describe the micro-behavior(aggregation,breakage,growth,etc.) of a disperse phase and its effect on particle size *** solution is the only choice in most *** this paper,three different numerical methods(direct discretization methods,Monte Carlo methods,and moment methods) for the solution of a PBE are evaluated with regard to their ease of implementation,computational load and numerical *** attention is paid to the relatively new and superior moment methods including quadrature method of moments(QMOM),direct quadrature method of moments(DQMOM),modified quadrature method of moments(M-QMOM),adaptive direct quadrature method of moments(ADQMOM),fixed pivot quadrature method of moments(FPQMOM),moving particle ensemble method(MPEM) and local fixed pivot quadrature method of moments(LFPQMOM).The prospects of these methods are discussed in the final section,based on their individual merits and current state of development of the field.

关键词： population balance equation direct discretization method Monte Carlo method moment methods disperse phase system

LINEAR ACTIVE STRUCTURES AND MODES (Ⅰ) —BASIC CONCEPTS AND PROPERTIES

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Applied Mathematics and Mechanics(English Edition) 2004年第8期25卷 845-853页

作者：张景绘龚靖school of civil engineering and Mechanics Xi'an jiaotong University Xi'an 710049 P.R.china Department of civil engineering Northeast china Institute of Electric Power Jilin 13.012 P.R.china 王永刚school of civil engineering and Mechanics Xi'an jiaotong University Xi'an 710049 P.R.china school of Science Chang'an University Xi'an 710064 P.R.china school of civil engineering and Mechanics Xi'an Jiaotong University Xi'an 710049 P.R.China

Some basic concepts about the active structures were firstly explained, and the main subjects to study in the field of active structure dynamics were synthesized. For the linear active structures, the annotations on the modes were done in detail. The physical meanings of the right and left eigenvectors were explained. The right eigenvectors are the modal shapes and the modal responses of an active structure depend on the left ones. The adjoint structure of an active structure was defined and the reciprocity theorem was interpreted. For two active structures, which are adjoint to each other and with the reciprocal gain-matrices, the right and left eigenvector are reciprocal. The relationship between an active structure and the corresponding passive structure is expressed with the transfer functions, which is employed to resolve the estimation problems.

关键词： active structure vibration control smart structure mode

SINGULAR BEHAVIORS OF INTERFACIAL CRACKS IN 2D MAGNETOELECTROELASTIC BIMATERIALS

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Acta Mechanica Solida Sinica 2009年第3期22卷 232-239页

作者： Cuiying Fan1 Youhe Zhou1 Han Wang2 Minghao Zhao1,2(1Key Laboratory of Mechanics on Disaster and Environment in Western china,the Ministry of Education of china,and Department of Mechanics and engineering Science,College of civil engineering and Mechanics,lanzhou University,lanzhou 730000,china)(2school of Mechanical engineering,Zhengzhou University,Zhengzhou 450001,china) Key Laboratory of Mechanics on Disaster and Environment in Western china the Ministry of Education of China and Department of Mechanics and Engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou China school of Mechanical engineering Zhengzhou University Zhengzhou China

The singular characteristics of stress,electric displacement and magnetic induction fields near the tip of impermeable interfacial cracks in two-dimensional magnetoelectroelastic bimaterials are studied using the generalized Stroh *** types of singularities are ob-tained:one is the oscillating singularity 1/2±iε,the other is the non-oscillating singularity 1/2±κ.It is found that the non-zero parameters ε and κ cannot coexist for one transversely isotropic MEE bimaterial,a similar result is obtained for transversely isotropic piezoelectric bimaterials.

关键词： generalized Stroh formalism magnetoelectroelastic bimaterial interfacial crack singularity index

A note on the derivation of the derivatives of invariants of stretch tensor to the right Cauchy-Green tensor

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Progress in Natural Science:Materials International 2006年第1期16卷 96-99页

作者： TIAN Dongyan, JIN Ming and DUI Guansuo (Institute of engineering Mechanics, school of civil engineering and Architecture, Beijing jiaotong University, Beijing 100044, china) Institute of engineering Mechanics School of Civil Engineering and Architecture Beijing Jiaotong University Beijing 100044 China

A new approach for the derivation of the principal invariants of the stretch tensor with respect to the right Cauchy- Green tensor is presented in this paper. According to the definition of the derivation of tensor function, the three first-order derivatives for the principal invariants of the stretch tensor are obtained through derivation directly to the right Cauchy-Green tensor by incremental method. Then the three second-order derivatives are yielded by the derivation to the right Cauchy-Green strain tensor directly. Furthermore, an explicit expression of the tangent modulus of the general Varga material is given as an example.

关键词： continuum mechanics invariant strain energy tangent modulus.

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斜交连续箱梁桥的温度应力与位移研究

铁道学报 2009年第4期31卷 82-86页

作者：张元海李乔兰州交通大学土木工程学院甘肃兰州730070 西南交通大学土木工程学院四川成都610031

以单根斜梁模型模拟斜交连续箱梁,在三力矩方程基础上,分析非线性日照梯度温度作用下斜交连续箱梁的温度应力和位移,系统研究斜度和弯扭刚度比对三跨斜交连续箱梁温度应力和位移的影响,绘制的大量曲线清晰显示了其影响规律。研究结果表... 详细信息

以单根斜梁模型模拟斜交连续箱梁,在三力矩方程基础上,分析非线性日照梯度温度作用下斜交连续箱梁的温度应力和位移,系统研究斜度和弯扭刚度比对三跨斜交连续箱梁温度应力和位移的影响,绘制的大量曲线清晰显示了其影响规律。研究结果表明,在常用斜度范围内,中跨梁底拉应力和梁顶压应力随斜度的增大而减小,随弯扭刚度比的增大而增大;边跨跨中有较大的上拱位移,且其值随斜度的增大而减小,随弯扭刚度比的增大而增大;中跨跨中位移随斜度增大将由下挠转变为上拱,其临界斜度随弯扭刚度比的增大而增大。

关键词：斜交箱梁斜交连续梁温度应力温度位移非线性温度梯度

CONTACT FRICTION ANALYSIS AND STRESS OSCILLATION SUPPRESSION WITH A SIMPLE INTERFACE ELEMENT

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Acta Mechanica Solida Sinica 2000年第1期13卷 33-41页

作者： Lei Xiaoyan (Department of civil engineering,East china jiaotong University,Nanchang 330013.china) Department of civil engineering East China Jiaotong University Nanchang 330013 China

A simple interface element for analyzing contact friction problems is developed. Taking nodal displacements and contact stresses as unknowns, this element can simulate frictional slippage, decoupling and re-bonding of two bodies initially mating or having gaps at a common interface. The method is based on the Finite Element Method and load incremental theory. The geometric and static constraint conditions on contact surfaces are treated as additional conditions and are included in stiffness equations. This simple element has the advantages of easy implementation into standard finite element programs and fast speed for convergence as well as high accuracy for stress distribution in interface. Undesirable stress oscillations are also investigated whenever large stress gradients exist over the contact surfaces. Exact integration or the conventional Gauss integration scheme used to evaluate the interpolation function matrix of the interface element is found to be the source of the oscillations. Eigenmode analysis demonstrates that the stress behavior of an interface element can be improved by using the Newton-Cotes integration scheme. Finally, the test example of a strip footing problem is presented.

关键词： contact friction interface element stress oscillation eigenmode analysis