The Finite Element Simulation of Pipe Bend Forming

A dynamic explicit finite element method is used to pipe bend forming processes on bender in this paper.The degenerated shell element and co-rotational coordinate system are employed.The material of pipe is assumed to satisfy Hill's anisotropic elasto-plastic yield condition.The bend die and press die are assumed as rigid surfaces and the contact force is computed by penalty method.Several numerical examples are given.They show that this method is effective.     

Force Analysis on Meshing Surface and Stress Research of the Cone Roller Enveloping Worm Gearing Transmission

By using the finite element elastic contact analysis method combined with the I-DEAS engineering analysis software, this paper studies the strength of the cone roller enveloping worm gearing,which is a new type of worm gearing transmission,on SUN-4 working station. It also analyzes loading distribution among meshing gears, the contact force distribution along the contact line ,the bending stress distribution and the contact stress distribution of the cone roller enveloping worm gearing with three-tooth meshing instantaneously. Besides,it provides the theoretic basis in the further researches for the new type of worm gearing transmission.     

Application of Extended Finite Element Method to Fracturing Analysis of Gravity Dam

The extended finite element method(XFEM) presented in recent years is a new and effective method for discontinuity analysis,especially fracture problem analyses.The basic XFEM principle is introduced and the technique for fracture analysis is presented.The fracturing process of a gravity dam is simulated by XFEM,and the rules of stresses and displacements distribution are analyzed.Compared with the classical finite element method,the crack growth in the gravity dam can be modeled by XFEM without making the crack surface associate with the finite element mesh and setting dense mesh near the crack tip as well as remeshing after crack growth.The cumbersome work and disadvantages in conducting fracturing analysis by the finite element method thus can be avoided.The predominance of this method for dam fracturing analysis is displayed.     

Determination of Load Share between Gear Teeth with Contact Finite Element Method

The determination of load share between teeth is a complex problem in gear strength calculation. On the basis of contact finite element method this paper considers the production-assembly error as initial gap to get the finite element model which meets load share between teeth in gear meshing. Through calculating and comparing the result with that from ISO formula to get the load share between teeth which meets the requirements in actual usage.     

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]     

A Finite Element Method for Quasi Static Problems of Two phase Porous Media

For the quasi static problems of two phase porous media,the velocity variable of fluid phase can be eliminated as the viscosity of fluid is neglected.The corresponding governing equations,with displacement of solid phase and pore pressure as basic variables,as well as the boundary and initial conditions are given out.Finally a mixed finite element formula with u S-p variables is obtained with weighted residual method.This method has lesser nodal variables and higher accuracy of pressure distribution.     

Finite Element Analysis and Experimental Research on Pedestal of PC Beam for Light Railcar

In design of light railcar used freely supported beam, the cast steel pedestals will bear complex loads, which include weight, acceleration and wind, etc. Because of pedestals' peculiarity and complexity, the strength of the pedestals play an important role in safety of light railcar. So it's necessary to analyze their stress and deformation in order to insure safety of light railcar. Up to now, finite element analysis is still the most effective means. By studying cast steel pedestal with finite element method, 3-D finite element models of fixed and kinetic pedestals were built, and the loads and boundary condition of pedestals were analyzed. By means of finite element analysis software, the contact and von mises stresses were obtained and deformation were resolved. As a result of analysis, the tow of pedestal can fulfill requirement of use in light railcar, the contact stress and von mises stress are not exceeded limit stress strength of materials. There is enough static strength for the structures of pedestals. For verifying theoretical analysis result, the fatigue test was carried out, with examining the testing points locating on the pedestals, the stress and deformation data were measured. By comparing between theoretical analysis and test data, the experimental results show calculated and testing results can meet the case well which assure the reliability of finite element analysis. But in the result, there are differences in deformations of them. The reason may be that boundary conditions and loads are not same between analysis and experiment.     

Finite Element Method of 3D Stable Heat Conduction of Steel Fluid in Continuous Casting Moulds

The heat transfer of steel fluid in continuous casting mould is a stable process and can be depicted with three-dimensional stable heat conduction equation depending on tension speed. The corresponding finite element equation, including the first, second and third boundary conditions, is deduced out with Galerkin residual method. The coded FEM program is used to analyze the temperature distribution of Q235 steel in continuous billet casting mould. The method proposed is a foundation of thermo-mechanical coupled analysis for the formation of solidified shells and stress in the shells in continuous casting.     

离散元法在农业工程领域的应用进展

简述了离散元法在农业工程领域方面的研究成果,根据离散元法在农业工程领域的不同应用,分别讨论了离散元法在土壤散体颗粒、农业物料颗粒、多相流中单相介质的应用研究现状,指出了存在数量级受限,颗粒模型不精准,复杂工况制约等问题。提出今后离散元法的研究趋势:开发农业工程领域的专用离散元软件,提高颗粒群的运算效率;通过准确获取物料的细观参数,从理论基础上完善接触模型,使仿真颗粒与真实颗粒更为接近;通过离散元法软件与其他软件耦合,结合API的二次开发,拓宽离散元法在复杂散体颗粒运动仿真的应用。     

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.     

Dynamic Constitutive Model of Steel Fiber Reinforced Concrete and Its Finite Element Method

Taking the split Hopkinson pressure bar(SHPB) test data as training samples, an implicit dynamic constitutive model of steel fiber reinforced concrete(SFRC) was proposed with the improved BP neural network program. On the basis of ABAQUS/Explicit, a user defined material subroutine VUMAT was compiled with FORTRAN language, embedding with the neural network constitutive model into finite element calculation. With SFRC structure＇s response under impact load as case study, it is shown that the constructed constitutive model and its finite element method are effective.     

Deformable B-spline Curves and Surfaces Model and Its Finite Element Solution

Deformable models are of great importance for contour extraction and surface reconstruction, which cause the deformable models deform to the object contours due to simulated external force.Deformable B spline models can share the merit of the popular used B splie. From the Lagrangian mechanics, the dynamics equation of deformable B spline curve and surface is derived. Its finite element solution is studied including the finite element generation and element matrix calculation. A example is given to verify its validity.     

Post-process of Finite Element Method in Electrical Impedance Tomography

In the research of electrical impedance tomography (EIT), each calculation may produce a large amount of data(such as conductance , resistance etc.). The rule of these data is not clear and is hard to understand. How to express the calculation result by means of image in order that such parameters as conductance and resistance can be grasped from the image is significant in analyzing and understanding the calculation result and is helpful to the doctor. This paper has discussed the realization of the post-process of finite element method in electrical impedance tomography and we have developed the software of the post-process of finite element method using Visual C++ .NET and OpenGL. Some problems in drawing the contour line and color contour band have been solved properly.     

Hyperelastic Constitutive Relations and Finite Element Formulation for Porous Silicone Rubber

The strain energy density function which was decoupled into isochoric parts and volumetric parts is presented for describing mechanical behaviors of compressible porous silicone rubber material,the constitutive model is then attained.The finite element formulation for isotropic hyperelastic porous silicone rubber is developed by use of total Lagrangean method.     

Evaluation of the Energy Release Rate of Three-point-bending Beam Using Finite Element Method

Calculation of the energy release rate with finite element method (FEM ) is conducted. The concrete beam model is meshed using a method without need of considering the crack-tip singular element. Two columns of nodes, which belong to the right-and left-parts of the beam, respectively, are generated on the central line of the model and released one after another in a proper sequence. Energy release rate is evaluated based on the virtual crack closure technique. Comparison between the calculated values and theoretical values is made, which shows that they are in good agreement.     

A New Spline Boundary Element Method

This paper introduces a New Spline Boundary Element Method, which neither has corner problems and singular integrals nor involves extreme-conditions of spline function. Three numerical examples are given to show the validity of the method.     

Finite Element Programming Based on Template Chain Structure

Traditional Finite Element Method is the structuralization programming method and the structuralization language (such as FORTRAN). Its data store uses fixed array structure, which makes the expanding ability of program limited, code's reuse ratio low, debugging complex. The template is an opposite new important characteristic of the object-oriented programming language C++. The template can quickly establish class library so as to increase greatly the development speed of the large software. The object-oriented programming concept is applied to finite element method. According to the nature of the finite element analysis, the classes and their methods, which describe virtual element, node, material etc., have been developed and implemented using the object-oriented programming language C++. The elements, nodes and materials are stored by chain. Many type's elements are stored mixedly by polymorphism characteristic. The program is implemented and a instance is given to show the programming of finite element method. The results show that the period of programming and debugging is obviously shorter than that of traditional method; the code's utilization ratio is also increased obviously.     

Application of ANSYS to Finite Element Analysis for Nonlinear Masonry Structures

ANSYS has become an effective tool for finite element analysis of masonry structure, but there is few common conclusions for reference. According to the characteristics of ANSYS and the essence of the analysis, some key problems in finite element analysis of masonry structure with ANSYS, such as structural modelling, material constitution, the damage criterion, iterative algorithm, convergence criterion, simulation of prestressing force and so on, are discussed in this paper. Based on the test results of typical masonry structures, the applicability of ANSYS to masonry structural analysis is studied and some suggestions for the application of ANSYS are presented.