检索结果-南通市图书馆

Journal of Materials Science & Technology 1998年第6期14卷 574-576页

作者： Li ZHOU(department of civil engineering, Wuyi University,Jiangmen 529020, china) department of civil engineering Wuyi University Jiangmen 529020 China

The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the microscopic parameters of critical void growth ratio RC/RO were quantitatively measured under SEM. Then, the coefhcient C in the relation VGC = C In(RC/RO) proposed in author's past work was specifically explored. The correlation of C with tensile proderty parameter φ=σyδ/(Eφn) was presented for the Steel investigated, and the effects of low temperature on C were also discussed. Results show that the coefficient C is linearly related to the parameter and insensitive to low temperature.

关键词： GC with Critical Void Growth Ratio R_C/R_O Factors Affecting the Relation of Fracture Toughness V

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

在线全文

学校读者我要写书评

暂无评论

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) E china Jiaotong Univ Dept Civil Engn Nanchung 330013 Peoples R 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

Diffraction of plane SV waves by a cavity in poroelastic half-space

在线全文

学校读者我要写书评

暂无评论

Earthquake engineering and engineering Vibration 2009年第1期8卷 29-46页

作者： Liang Jianwen and Liu Zhongxian department of civil engineering, Tianjin University, Tianjin 300072, china Professor PhD Candidate department of civil engineering Tianjin University Tianjin 300072 China

This paper presents an indirect boundary integration equation method for diffraction of plane SV waves by a 2-D cavity in a poroelastic *** Green＇s functions of compressive and shear wave sources are derived based on Biot＇s theory. The scattered waves are constructed using fictitious wave sources close to the boundary of the cavity, and their magnitudes are determined by the boundary conditions. Verification of the accuracy is performed by：（1） checking the satisfaction extent of the boundary conditions, （2） comparing the degenerated solutions of a single-phased case with well- known solutions, and （3） examining the numerical stability of the solutions. The nature of diffraction of plane SV waves around a cavity in a poroelastic half-space is investigated by numerical examples.

关键词： poroelastic half-space cavity diffraction plane SV waves compressive wave source shear wave source Green's function pore pressure

Conservation laws for mechanical systems with unilateral holonomic constraints

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2004年第1期14卷 56-60页

作者： ZHANG Yi*(department of civil engineering, University of Science and Technology of Suzhou, Suzhou 215011, china) Univ Sci & Technol Suzhou Dept Civil Engn Suzhou 215011 Peoples R China

A general approach to the construction of conservation laws for mechanical systems with unilateral holonomic constraints by finding corresponding integrating factors is presented. The definition of integrating factors for the Routh equations of motion of the systems is given, and the necessary conditions for the existence of conserved quantities of the unilateral holonomic constraint systems are studied in detail. The conservation theorem and its inverse for the systems are established, and an example is given to illustrate the application of the results.

关键词： unilateral holonomic constraint integrating factor conservation theorem Killing equation

Analytical theory of flexural behavior of concrete beam reinforced with textile-combined steel

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第6期53卷 1700-1710页

作者： XU ShiLang & YIN ShiPing department of civil engineering,Dalian University of Technology,Dalian 116024,china 1. department of civil engineering Dalian University of Technology Dalian 116024 China

Textile-reinforced concrete (TRC) is a new high performance cementitious composite material,which not only has superior corrosion resistance but also can effectively limit the development of concrete cracks and make the crack width and spacing of concrete become ***,due to the brittle feature of fiber materials,the TRC structural member has no distinct failure symptom when it arrives at its ultimate *** the same time,ordinary reinforced concrete (RC) elements have large dead weight and can not efficiently restrict the expansion of the main crack of structures because of the restriction of their special cover *** order to overcome the disadvantages of both the TRC and the RC,a new architecture reinforced with textile-combined steel is proposed in this study,making full use of the advantages of the above two *** cover concrete at the tension zone of an RC element is partially replaced with TRC and thus the steel reinforcements replaced with textiles are *** with the old one,the new structure has less dead weight and has the merits of service safety and good *** flexural development process of the proper beam with this new structure is investigated in this paper and based on the plane section assumption,analytical equations are derived by using nonlinear analysis theory,including the load-carrying capacity at different stages and moment-curvature relationship and mid-span deflection during the entire loading *** between the calculated and the experimental results reveals satisfactory agreement and thus verifies the feasibility of the equations.

关键词： textile-reinforced concrete limiting the crack beam reinforced with textile-combined steel flexural behavior analytical theory

Analysis on cohesive crack opening displacement considering the strain softening effect

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2 & ZHAO Xiqiang3 1. Mechanics department, Shandong University of Technology, Zibo 255049, china 2. civil engineering department, Dalian University of Technology, Dalian 116024, china 3. Mathematics department, Ocean University of china, Qingdao 266071, china Mechanics department Shandong University of Technology Zibo 255049 China civil engineering department Dalian University of Technology Dalian 116024 China Mathematics department Ocean University of China Qingdao 266071 China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

Study on multi-scheme analysis and evaluation method for concrete sequence placement of high arch dam

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2011年第S1期54卷 47-53页

作者： ZHONG GuiLiang,REN BingYu & TONG DaWei department of Hydraulic and Hydroelectric engineering,School of civil engineering,Tianjin University,Tianjin 300072,china 1. department of Hydraulic and Hydroelectric engineering School of Civil Engineering Tianjin University Tianjin 300072 China

A complete scheme for solving the key scientific problems of how to make concrete sequence placement scheme of high arch dam reasonable and feasible and how to meet the need of construction process was ***,based on a coupling analysis of concrete sequence placement system of high arch dam,a mathematical model considering complex construction constraints was ***,a multi-scheme computational analysis method for concrete sequence placement of high arch dam was proposed based on dynamic ***,a multi-scheme evaluation method for concrete sequence placement was put forward based on analytic hierarchy ***,feedback guidance for progress control and management in the high arch dam construction process was ***,these methods were applied to a practical project to show that the methods can analyze and evaluate multi-scheme for concrete sequence placement of high arch dam effectively,optimize the process of dam concrete sequence placement,and recommend engineering *** methods provide new theoretical principles and technical measures for real-time progress control in the high arch dam construction.

关键词： sequence placement analysis multi-scheme evaluation dynamic simulation analytic hierarchy process high arch dam construction

Research on analysis method for temperature control information of high arch dam construction

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2011年第S1期54卷 40-46页

作者： ZHONG DengHua,ZHAO ChenSheng & REN BingYu department of Hydraulic and Hydroelectric engineering,School of civil engineering,Tianjin University,Tianjin 300072,china 1. department of Hydraulic and Hydroelectric engineering School of Civil Engineering Tianjin University Tianjin 300072 China

Temperature control,which is directly responsible for the project quality and progress,plays an important role in high arch dam *** to discover the rules from a large amount of temperature control information collected in order to guide the adjustment of temperature control measures to prevent cracks on site is the key scientific *** this paper,a mathematic logical model was built firstly by means of a coupling analysis of temperature control system decomposition and coordination for high arch ***,an analysis method for temperature control information was presented based on data mining ***,the data warehouse of temperature control was designed,and the artificial neural network forecasting model for the highest temperature of concrete was also ***,these methods were applied to a practical project. The result showed that the efficiency and precision of temperature control was improved,and rationality and scientificity of management and decision-making were *** of these researches provided an advanced analysis method for temperature control in the high arch dam construction process.

关键词： high arch dam construction temperature control information data mining data warehouse neural network model

A new orthogonality relationship for orthotropic thin plate theory and its variational principle

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2005年第3期48卷 371-380页

作者： LUO Jianhui 1 , LONG Yuqiu 2 & LIU Guangdong 1 1. College of civil engineering, Hunan University, Changsha 410082, china 2. department of civil engineering, Tsinghua University, Beijing 100084, china 1. College of civil engineering Hunan University 410082 Changsha China 2. department of civil engineering Tsinghua University 100084 Beijing China

The thought how dual vectors are constructed in a new orthogonality relationship for theory of elasticity is generalized into orthotropic thin plate bending problems by using the analogy theory between plane elasticity problems and plate bending problems. Dual differential equations are directly obtained by using a mixed variables method. A dual differential matrix to be derived possesses a peculiarity of which principal diagonal sub-matrixes are zero matrixes. Two independently and symmetrically orthogonality sub-relationships are discovered. By using the integral form for elastic bending theory of orthotropic thin plate the orthogonality relationship is demonstrated. By selecting felicitous dual vectors a new orthogonality relationship for theory of elasticity can be generalized into elastic bending theory of orthotropic thin plate. By using the integral form a variational principle which is relative to differential form and a whole function expression are proposed.

关键词： theory of elasticity, thin plate theory, dual vectors, orthogonality relationship, orthotropic, variational principle.