Application of Object-oriented FEM in Developing Simulation Software System

Based on object-oriented method, the classes of object-oriented finite element are defined. The finite element program of static, dynamic characteristics and stability analyses for spatial frame structures is developed with c++ object_oriented language which is successfully incorporated into a computer simulation system of derricks. The results of static, dynamic characteristics and stability analysis for the derricks of F320-A and JJ250/42-K types, obtained with the developed system, are consistent with those obtained by a commercial software, which illustrates the correctness of object-oriented FEM and the reliability of the simulation software.     

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.     

Preprocessor of Reinforced Concrete FEM Analysis

Reinforcing element and concrete element have effects on the order of the stiff-matrix of the reinforce-concrete FEM. The program divided the elements is programmed by FORTRAN language in current analysis, and the data of the elements are stored by the array. The stiff-matrix of the reinforce-concrete FEM is extended by the large residual between the serial numbers of the nodes of cohering element. This paper establishes the graph class, path class and point class via objectoriented programming. The storage of the points and the paths by the chain structure realization of copying graph, moving graph, adding graph, continuously numbering the cohering elements are built. This paper presents the example of the dividing domain with the crack.     

Dynamic FEM Analysis of Automobile and Software Development

In this article, modal analysis technology about dynamic analysis was studied. Free interface model comprehensive method was used to dynamic analysis and design of automobile structure based on theory background of model analysis, test technology conditions, data reliability and precision. In order to test the efficient and possibility of the method, main vibration features about space double layer has been calculated based on this method, comparing this with the precise solution of finite element method, the result shows that this method is suitable not only for simple interfaces between components but also for high reductive interfaces. In addition, the method also has high comprehensive precision. Furthermore it creates conditions to dynamic analysis in automobile structures.     

FEM analysis on the earth pressure behind the panel of post-panel retaining wall

the distribution of earth pressure behind the panel of post-panel retaining wall is analyzed with 3-D FEM. Eight-crunode isoparametric element is adopted, concrete is regarded as linear elastic object, soil is regarded as elastic-plastic object, an interface model is introduced to simulate the interaction between concrete and soil.It is demonstrated that the earth pressure behind the panel of post-panel retaining wall is greatly different from the classical earth pressure theory, its distribution is close to a parabola. Based on FEM analysis, a modified formula is induced to calculate the earth pressure behind the panel of post-panel retaining wall, the engineering design by this modified formula will be more economical and reasonable.     

Calculation of the ampacity of XLPE power cable based on FEM and analysis of the influential factors

Based on the principle of heat transfer theory and finite element method (FEM), a model for power cable thermal field and ampacity computation has been developed by adopting the soil region division method. The soil region around the cable is divided according to the difference of the soil thermal resistance. Based on the structural parameters of XLPE cable and the physical parameter of the laying area, different layers temperature distribution of XLPE cable is analyzed through the model, and the dichotomy is employed to calculate the cable ampacity. Comparing the calculated result by this method with the calculation by the standard, shows that compared to IEC60287 standard, the model has high-accuracy and is more convenient to the external environment. Through simulation example, the corresponding relationship between the influencing factors and the cable ampacity is obtained, which provides important theoretical basis for the optimization of the cable laying.     

FEM Analysis of Differential Settlement of Gravel Pile Foundation Under Large scale Oil Tank

In order to reduce the differential settlement of gravel pile foundation under large scale oil tank, axisymmetric numerical simulation method and finite element method was employed to study the pile length, the exchange rate of length, the length of the cushion course to the influence of differential settlement and the relationship of negative lateral displacement and the settlement. It is found that: differential settlement has a minimum range of pile length. For the oil tank foundation center, by keeping the pile diameter, increasing pile spacing can increase the rate of exchange and obtain smaller differential settlement in relatively smaller displacement rate conditions. And by keeping replacement rate unchanged, the larger the pile diameter(namely the looser pile spacing) is, the smaller the differences settlement of the gravel pile foundation is. Moreover, pile length adjustment and the exchange rate have obvious effects on different subsidence and not obvious effects on the length of the cushion course. The appearance of oil tank foundation negative lateral displacement is one of the most important features of differential settlement adjustment.     

A Method Coupling FEM and Singular Solution of Infinite Plane with a Hole for Underground Engineering

In this paper, a simpler and direct coupling method, i.e. finite element method coupled with singular solution of infinite plane with a hole, is proposed for the analysis of underground engineering. The numerical example shows that the elastic effectiveness of the infinite plane outside the artificial boundary upon the inside region is exactly expressed.     

Study on Temperature Fiele of Cast Iron Compound Roll in Slab Hot Rolling

In this paper,a finite element method coupling thermo-elasticity is used to ana-lyze the temperature field of cast iron compund roll in hot rollin8 slab mill.A technique to deal withthe bou ndary of heat and load in rotation is developed.     

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.     

Test and FEM Analysis of Junior Beam Deflection Influenced by Steel Floor Sheet

For light gauge steel floor,the structure testing and finite element method were applied to study the junior beam's inflection capability influenced by steel floor sheet.Analysis results show that the thin steel floor sheet affects junior beam's deflection very strongly.This conclusion has value for design of new structure or evaluating load support capability to the steel floors.     

Analysis of the Double-layer Sub-grade with Rigid Upper Layer and Soft Lower Layer by FEM

The double layer subgrade with rigid upper layer and soft lower layer is common in engineering construction. In this paper, the elastic and elasto-plastic analysis on such subgrade by ANSYS was carried out. According to the calculation results of FEM, the plastic zone of subgrade would appear in the upper layer soil of interface, then, it would be expanded up and down with increase of the load. As for the lower layer soil is relatively soft, the plastic zone is expanding rapidly. Finally, as the plastic zone reaches the bottom and the subgrade in the state of ultimate bearing capacity, the calculation starts to be non-convergent. The results can serve as reference to the engineering designers.     

Acoustics simulation and structure optimization of a motorcar exhaust muffler

Aiming at the exhaust muffler of a 244S motorcar, the acoustics field model and the flow field model are established by adopting Finite Element Method. The 3-D acoustic simulation is carried out by using software SYSNOISE, and an improvement scheme with optimized inner structure of the muffler is proposed based on the simulation. The acoustic simulation result and the bench test result of the improved muffler show that the muffling ability in middle and high-frequency of the improved structure is obviously stronger than the original structure, and the simulation result coincides well with the bench test result. Meanwhile, the flow field simulation result shows the power loss of the engine has little change, which means that the structure improvement of the original muffler is effective.     

Experiment and FEM Analysis on the Joint of Inserted Steel Beam

A new composite structure which is composed of steel beam and concrete girder is introduced in fuel electric plant construction. With different height of concrete girders with or without anchor bar, two scale models from an actual project were designed and tested. It is shown that the maximum restraining moment of ends of steel beams is approximately 60kN*m; influence of anchor bar is little; the one with 600mm high concrete beam is damaged by shear, and the others steel beam is damaged by bending failure. Finite element models were built for supplementary analysis, and the result indicates that critical value of the height of concrete beam of different failure modes is 700mm; stiffness of shear key and thickness of floor have great influence on the structure; size of anchor bar has little influence; and width of the end of the steel beam has certain influence.     

Application of a FDTD/MOMTD Hybrid Method to the Scattering Problem of the Ground Penetrating Radar

In order to analyze and research the scattering problem of the ground penetrating radar under the ground, a hybrid method combining FDTD and MOMTD is constructed to solve the problem. The curve of current on central feeding point of pick-up antenna is obtained by simulating when different distance between the ideal conductor and the ground is considered, correctness of the result gained by employing the hybrid method is proved through qualitative and quantitative analysis.     

Numerical analysis of material surface thaw depth under pulsed electron beam irradiation

We developed a finite element method model. An equality heat source was used to thaw metal with an electron beam in numerical analysis. The temperature field was obtained after the metal thawed with electron beam by numerical analysis. The influence of the material thaw depth was analyzed at differing voltages, energy densities, and energy evenness. A thaw depth diagram was obtained where energy evenness is from 0.9 to 1.0, energy density is from 2 J/cm2 to 17 J/cm2, and voltage is from 25 kV to 50 kV. The change rule of material thaw depth was derived which provides a theoretical reference for fine mould machining with electron beams.     

Analysis of spatial electric field with point-plateelectrodes configuration using finite element method

To investigate the spatial electric field with the point-plate electrodes configuration, variations of the electric field intensity are analyzed for absolute air dielectric and liquid dielectrics contained in air dielectric based on the finite element method of numeric computation. The results show that the electric field intensity of the spatial electric field is great non-uniform with the point-plate electrodes configuration for absolute air dielectric, and it can be increased rapidly at the nozzle point to achieve a maximum value. Single oil drop existed in air dielectric induces a biggish deformation of the gradient of the electric field intensity in its neighbor field. Many oil drops along with horizontal distribution have an obvious tensioning operation on the electric field, so the electric field intensity on the normal at the nozzle point has an evident augment for overlapping effects among the oil drops, and it can spread electric corona area of the total spatial electric field.     

Application of Magnetic Analysis in Magneto-rheological Damper Performance Estimation

As a kind of semi-active controllable devices,Magneto-rheological(MR) damper has been increasingly widely used in various occasions of vibration suppression.However,the design of MR damper greatly depends on the engineering experience of designers,it is difficult to calculate the performances relatively accurate.With the Finite Element Method,the authors carry out the magnetic analysis on the given geometry of MR damper combined with the Couette flow analysis of MR damper,the dynamic curve of MR damper is obtained.The results show that the FEM magnetic analysis effectively predicts the yield shear force and flow shear force,it is coincident with the experimental data.It is validated that the methods described is suitable for the MR damper performance estimation of the same geometry,and is an effective means for the MR damper design with the given force.