Advance in Mathematic Model of Solidification Heat Transfer Process in Continuous Casting

The mathematic model of solidification heat transfer process in continuous casting strand is useful for quantitatively analyzing heat transfer in continuous casting process, quality control and process control. The heat transfer in continuous cast strand in crystallizer and secondary cooling zone have been analyzed. The attention has been paid to basic logic and methodology in model building up. Typical methods determing solution condition and parameters for the model have been discussed. Some numerical methods at the present time for solving solidification heat transfer model, such as finite difference method, finite-element method and boundary element, have been investigated comparatively. In the future, working on solidification heat transfer model, which is more practical, and the integration of the control model will play an important role in the development of high efficiency continuous casting technology.     

3-D Finite Element Analysis of Solidified Shell in Molds for Continuous Casting of Thin Slabs

A three-dimentional thermal elastoplastic contact FE analysis model of solidifiedshell in moulds for continuous casting of thin slabs is set up, based on the known geometry of theshell and the temperature distribution in the shell. We in turn obtain the stress and Strain distributions of the solidified shells formed in lSP and CSP moulds,the gap distributions between the Shellsand the mould walls,as well as the curves of cracking index [1] in the shells,which provides afoundation for the design and control of technical parameturs for continuous casting of thin slabs.     

The Mathematical Model of Cooling and Heat Transfer for the Solidification of Thin Slab during Continuous Casting Process

In the established model, the cooling differences are considered between the surface of inner radius and that of outer radius, and in the transverse direction of thin slab. And the conception for the effective coefficient of spraying water in continuous casting is firstly put forward. According to different casting speeds and different cooling zones, different time step lengths are adopted. In this model the heat transfer differences are thought over among vertical and curved zones, wide and narrow surfaces an well as angular zone of mould. The method of the corrected equivalent specific heat is used to deal with latent heat. The influence of forced convection is considered on heat transfer. Therefore, the model has higher accuracy and is consistent with the practice.     

Section Optimization Design of Steel-Concrete Continuous Composite Beams Based on the Finite Element Method

This paper introduces the efficient computer aided design method to optimize the section of steel-concrete continuous composite beams by combining FEM for structure analysis with optimization arithmetic and an efficient shearing force link model of steel-concrete composite beams.The authors established a finite element analysis model,optimization parameter model,optimization mathematics model of steel-concrete continuous composite beams and programs analysis file and optimization control file by using the ANSYS parameter design language. The optimum of the steel-concrete continuous composite beams section is obtained after computing and the optimization result indicates that this method is efficient in optimizing the section of steel-concrete continuous composite beams.So it could be applied extensively in the steel-concrete continuous composite beams section optimization design.     

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.     

Coupled Thermo-Elastic Contact Finite Element Method and It''s Application in Gearing

A new finite element method is presented in this paper to analyze the thermo- elastic contact problem with heat input on meshing tooth faces. The computational model of meshing gear has been established and the frictional heat input on meshing tooth faces is estimated. In addition, 2-D finite element analysis program for this kind of problem is listed. The test and practical examples are given to show the validity and versatility of this method.     

Mixed Finite Element Method for Dynamic Problems of Fluid Saturated Biphasic Porous Media

Based on the fluid saturated biphasic porous media model deduced from mixture theory,a finite element formulation with u S u F p variables for dynamic response analysis is given out.This method overcomes the difficulty of choosing suitable penalty parameter in penalty finite element method,and the accuracy of pressure distribution obtained with the mixed finite element method is higher than the penalty finile element method.An iterative solution method is suggested to solve the system of equations whose coefficient matrices are non positive definite.It is concluded from patch test that the order of interpolation function for pressure variables must be higher than that of displacement variables of solid phase.     

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 3D Visco elasto plastic Finite Element Analysis of the Asphalt Pavement Rutting Deformation

Based on the dynamic action between vehicles and pavement, a simplified model of vehicle dynamic loading caused by surface evenness was established. This research made it possible to find a Asphalt Pavement Rutting Prediction method based on the theory of visco elasto plasticity which is the basic theory of the dynamics, and finite element method (FEM). Asphalt pavement rutting was calculated and predicted, and the factors influencing rutting were analyzed and calculated. The good agreement between the calculation results and the testing road data indicate that the rutting prediction method is reasonable and reliable.     

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.     

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.     

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.     

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.     

Finite Element Analysis of the Influence of Steel Strength on Beam-to-column Composite Connections

Because high material strength and composite load-bearing are emphasized in constructing members for high-rise steel frame structures, in a composite connection, steel strength has a dramatic influence on both the bearing performance and the composite action of the concrete slab. Based on a finite element analysis, we discuss the composite effect and the connection breaking mode, focusing on the performance change of the composite effect in adopting high strength steel. It can be found from the results that, along with the improvement of the steel strength, the elastic and plastic ultimate strength of the composite connection will increase, the ductility will decrease to a certain extent, and the composite effect of the concrete slab will diminish. The collapse of the concrete in a positive moment side contacting the column flange is viewed as the limiting state of the connection.     

Computational Simulation on Temperature Field of Slab Continuous Casting Mold

On the core concepts that the distributing of temperature and solidified slab shell in mold are a stable process, a new method to calculate the temperature field in mold has been promoted. Consequently, a coupling model on fluid filed and temperature field in stable state has also been established. The concept of effective heat capacity is introduced to deal with the latent heat source term from phase transformation. During the programming for computation, the dynamic updating method is also applied to simulate the influence of solidification on physical properties. The resolution results of this model are analyzed and compared with the tested thickness of solidified shell from casting broke out slab, which demonstrates the correctness and applicability of this model to the practical continuous casting process. Additionally, the thickness distribution of solidified shell in slab mold are also studied in detail.     

An Improvement on the Gradual Subdivision of 2D Finite Element Mesh

In order to solve the uncontinuity of element numbering after the gradual subdivision of the triangular meshes, the correlation coefficient are introduced in this paper. It is easy to refine a multimedia-domain by using this method.