Elemental Stiffness Matrix of Thin-walled Beam and Its Application

In this paper, according to the conception of rotation of the section orthographic projection around a fixed axis, the element stiffness matrix of thin-walled beam is directly deduced and the direct stiffness method is used to solve the continuous beam problem with different shear centers on one section. It is suggested through an example that when the element flexibility matrix and force method are used to solve the same question, the same answer will be gained, but the method used in this paper is simpler.     

Scanning Beam Method for the Contour Graph

The tracing method is applied to generate the contour graph, it is difficult to find the start point of the interior closed contour beam. This paper presents a general scanning beam method which can be applied to generate color contour graph for elements with arbitrary shape by the object-oriented programming. We give visualization of the elements of triangle the element with 3 Points, triangle element with 6 Points, quadrilateral element with 4 Points, quadrilateral element with 8 Points, quadrilateral Element with 9 Points and the example by the MFC of Visual C++ R6.     

渐变刚度钢板弹簧建模方法对比

为更好地分析钢板弹簧刚度特性,对钢板弹簧建模方法进行了对比研究。依据钢板弹簧国家标准GB/T 19844-2005,针对某型渐变刚度钢板弹簧分别在有限元软件Hypermesh和多体动力学软件Adams中建立其有限元模型和离散梁模型,并进行了仿真,得到刚度特性。将仿真结果与试验值进行了比较。结果表明,在针对该钢板弹簧的刚度分析中,运用离散梁法得到的刚度特性更加接近试验值。     

Nonlinear Stiffness Matrices of Plane Beam Element Including Initial Stress and Strain Item

There were often happened cases for beam elements with initial stress or initial strain while the geometrically nonlinear analysis was performed for the plane structure. The deduction of stiffness matrices was awfully difficult because the nonlinear stiffness matrices included node displacement vectors and extensive matrix operations. Based on the nonlinear geometric equation of plane beam element and general elastic relationship of stress-strain including initial stress and initial strain,the tangent stiffness matrix was derived. All explicit formula of stiffness matrices including initial stress and strain item have been developed by use of the MATLAB Mathematical Tools. The results are of great significance to the nonlinear finite element programming for plane beam elements.     

Four-node Membrane Element of Vector Form Intrinsic Finite Element for Large Deformation Analysis of Membrane Structures

Based on fundamental principles of the vector form intrinsic finite element (VFIFE), the basic formulas of 4-node quadrilateral membrane element were first derived in this paper. The procedure for the determination of pure nodal deformation through reverse movement was elaborated, and the method for the calculation of internal nodal forces through deformation coordinate system was presented. Feasible approaches were also proposed for several issues for 4-node membrane element, including the location statuses and the numerical integration for internal forces. A computer program of 4-node membrane element was developed. By the analysis of the numerical example, the correctness and validity of the membrane element theory and the computer program were verified. Then the approach was applied for more analysis of large deformation and large rotation problems of membrane structures, including cushion inflating and cloth draping.     

Study and Application of High Precision Nonlinear Plane Stress Element

A tangent stiffness matrix for quadrilateral plane stress element under large rotation with small strain is proposed in this paper,The corresponding program based on this theory has been worked out;The computation of examples with analytic values has verified that the element's formulation, its program given in this paper have strong nonlinear computation ability;A nonlinear whole-course analysis of stone arch bridge has been done in this paper.The computations presented preferably a comprehensive understanding of nonlinear characteristics of stone arch bridge with small span and could be beneficial for the engineer designers.     

考虑剪切变形影响的桩基m法计算理论

考虑桩基的剪切变形影响,利用单广义位移深梁理论,建立了桩基m法的计算方法,导出了水平位移、转角、弯矩和剪力的初参数表达式和无量纲参数函数的统一表达式,根据桩底边界条件建立了初参数解的计算公式;给出了无量纲参数函数随换算深度和弯剪刚度比的变化图形。研究表明,换算深度小于3.0时,弯剪刚度比对无量纲参数函数影响较小,换算深度大于4.0时,弯剪刚度比对无量纲参数函数影响的趋势非常明显,桩基剪切变形的影响程度与桩的边界条件有关。算例结果表明,桩身的剪切变形有增大桩顶水平位移、提高弯矩零点位置、改变弯矩分布特征、扩大桩侧土压力大小等影响。     

Beam element end release by extra degree of freedom method

This paper develops a new method of extra degree of freedom (extra DOF) for the beam element with end release. Based on the strain matrix with extra DOFs, it derives the stiffness transformation matrix of released element, which can be applied to situations along global coordinate system or element local coordinate system. The effects of end release processing method for beams with large displacement are analyzed, and the results compared with those from other existing methods show that the extra DOF processing method has higher performance and accuracy.     

Galerkin Boundary Element Method for Laplace Equation

Galerkin method based on the variation principle is used to solve differential and integral equations. The boundary problem of Laplace equation is changed into the variational equation which is equivalent to the boundary integral equation. Using linear element, it is solved by Galerkin boundary element method. In computation of stiffness matrix, the exactly integral formula is used in the first order integral expression, The numerical integral formula is used in the second order integral expression. Thus the problem of calculation of double singular integral is carried out. The numerical experiments also prove this method is reliable. The error of Galerkin boundary element is tested with numerical experimentation.     

Sub-structural Method of FEM by the Object-Oriented Program

Some paper have presented the abstract element class of FEM, which the specific element class such as the triangle Element,the quadrilateral Element can be derived from. The substructure is the specific element class as the class derived form the abstract element class. The Object-Oriented FEM needs changing rearly when the sub-structural function is added to it. The Choleshi's disintegration of the sub-structural stiff is done and using the resolved triangular matrix many times can greatly reduce the work of the cohering matrix. The definition of the substructure class and the comparison between the sub_structural method and the normal method.     

Method of Geometric Rectification on Scanned Image From Papery Topographic Map

As a result of multiple factors, Scanned Images from papery topographic map will present the distorting errors. For the sake of rectifying the errors, the geometric rectification on scanned images is discussed. Based on the theory of finite element and the technology for image processing, the method of rectifying the distorting errors on the scanned image is presented. The method takes full advantage of reference points on the topographic map, and the region of map is partitioned into some quadrilateral elements by reference points, then bilinear equation is adopted to rectify the quadrilateral region one by one. The method not only makes the best of information of reference points, but also avoids operation of polynomial equation. Precision of rectifying the distorting errors on the scanned image is remarkably enhanced.     

A FINITE ELEMENT RESEARCH ON.A LINKAGE OF A COMPOSITE STRUCTURE OF SHELLS AND PLATES

In this paper,the penalty element stiffness matrix of linkage of plates and shells is deduced accrding to the principle of the penalty elementmethod.This stiffness matrix can be also used for a linkage between shells andsolids.It is of some practical value in the finite element calculations of engineeringstructure.     

The Influence of Beam Column Stiffness Ratio of Mine Shaft Tower to Shear Lag Effect

Making use of large finite element analysis software ANSYS, combine with the mine shaft tower actual frame tube structure project to model analysis, by means of concrete performance of mine shaft tower under the effect of horizontal load, come to a conclusion that beam column stiffness ratio has a great influence on shear lag effect. Then analyse the phenomenon of beam column stiffness ratio to shear lag effect, make a comparison on calculated results and simulation analysis results, to move an improved method. It has a great guiding significance for the mine shaft tower structural design.     

The Finite Element Method for Frame Structure with Fuzzy Elastic Connections

The connections of frame structure elements at a node are ofen an elastic connection between hinged and rigid.In this paper,the stiffness matrix and the loading transfer matrix of frame element with turn elastic connections is deduced,the cross shear effect has been taken into consideration simultaneously.The stiffness matrices of some bar elements,such as both ends of the bar are hinged or rigid and one end is hinged but the other is rigid,are special cases of the stiffness matrices presented in this paper.After pointing out that the elastic coefficient at a node of a bar element with elastic joint is really a fuzzy quantity,the fuzzy stiffness matrix of the bar element is obtained,and a solution to structural fuzzy finite element equilibrium equations is presented.The fuzzy solution obtained from above is not only containing the solution of ordinary finite element method but also providing some additional informations with practical value.[WT5HZ]     

Finite Element Simulate Analysis of Small Span-to Depth Ratio Coupling Beams with Special Reiforcement

Test investigations show that the reinforcement scheme with adding diagonal and rhombic bars to traditional reinforcement in the foundation is an ideal way, for the seismic performance of small span-to depth ratio coupling beams with this scheme is better than that of traditional reinforcement. Because the regions in the small aspect ratio coupling beam belong to D-regions, in which the Bernoulli hypothesis of plane strain distribution is invalid, the traditional bending theory can not be used. This paper simulates the coupling beam through non-linear finite element analysis program, and contrasts the analysis result of the bar's stress distribution with test result. The contrast results confirm that it is a valid way to analyse the bar's stress distribution in this coupling beam through non-linear finite element analysis program.     

Experimental Analysis of Rotational Behavior of Timber Beam-column Connection of Ancient Tibetan Architecture

Static experiment was carried out to study rotation behavior of timber beam-column connection. The influence of length of Gongmu and position of dowel on the initial rotational stiffness of the joint was analyzed. Rules of stiffness degradation under cyclic loading were studied as well. The results show that: the moment-rotation curve of typical timber beam-column connection can be simplified as bilinear model; the initial rotational stiffness of the joint is enhanced with the increase of the length of Gongmu, and it is decreased with the inward movement of dowel; under the same conditions, the influence of the inward movement of Gongmu-beam dowel on the initial rotational stiffness of the joint is smaller than that of Dianmu-Gongmu dowel; and stiffness degrades under cyclic loading and there exists obvious transition phenomenon.     

Finite Element Analysis of Spatially curved Rods

A system of governing equations for spatially curved rods are derived in natural coordinate,and an analytic solution to the statically determinate problem is given.Based on the solution,a generalized displacement model for element of curved bars is developed,which is convergent and accurate.     

forming process planning and technology realization of the monoblock break beam frame

In order to meet the performance demands of train lorry, a die forging drawing method based on structure features analysis was proposed to form the L A break beam frame. The finite element method was used to simulate a series of die forging processes and the drawing processes with different parameters. The optimum cross section shape of the performing die was obtained from these simulation results. It is found that local back flow of the metal is the primary cause of necking defects in drawing. Furthermore, the best drawing speed is determined to be from 87 mm/s to 96 mm/s. The results of trial manufacturing and product detection indicate that employing a die forging drawing process to form the monobloc break beam frame is feasible.     

Measurement and Analysis of Prestressed Concrete Flat Beam- Waffle Slab System During Prestressing

During the pre - stressing of the unbonded prestressed concrete wide flat beam - waffle slab system, the displacements and strains of slab and the prestressed concrete beams were site - measured and the results were analyzed. The prestressing construction was simulated by finite element program. The prestressing efficiency of the unbonded prestressed concrete wide flat beam - waffle slab system was discussed. It indicates that the prestressing efficiency was affected by the in -plane stiffness of slab.     

Non-linear finite element analysis based on the spatial catenary cables

According to the elastic catenary theory,this paper derives the spatial catenary cable element from the exact analytical expression,which is used for finite element analysis of the structure.It deduces the precise expression of two-node cable element tangent stiffness matrix and the tension of cable end.The equivalent node load of cable element is expressed by the total load algorithm,and the non-linear equation is solved by double Newdon-rapson method.The proposed non-linear semi-analytical finite element method based on spatial catenary cable element can take full account of the impact of non-linear geometry.The initial configuration and the internal forces on any directional spatial loads can be solved.The example shows that the calculation method is accurate and effective.