A Deformable Model Interpretation Based on the Theory of Elasticity

Deformable models provide a unified account of a number of visual problems, including contour extraction, motion tracking as well as 3D reconstruction and stereo matching. To get a reality-based interpretation of the deformable model and its parameters, an approach originates from the theory of elasticity is proposed. The conclusion is helpful to further understanding the behavior of deformable model. A new way is provided to research deformable models from the theory of elasticity.     

Effects of Thorax Muscle Fiber on Body Surface Potentials

A numerical method calculating the forward problem of electrocardiogram (ECG) has been presented. By using this method, the torso part including anisotropic muscle layers has been discretized by means of the finite element method (FEM). The rest of torso have been divided into the surface elements by the boundary element method (BEM). The effects of the skelltel muscle layers over thorax wall, have been discussed in terms of a three-dimensional torso models.     

Object-oriented FEM Program for Three-dimensional Convection Diffusion Problems

According to an analysis of three-dimensional convection diffusion problems and object-oriented programming method,the classes of finite element models for convection diffusion problems are designed in C++.There are vector classes,matrix classes,element classes,material classes and method classes of finite element among these classes.On the basis of these classes,an object-oriented finite element program for three-dimensional convection diffusion problems is accomplished,which is able to simulate similar problems.The program's reuse,maintenance expansion and integration with other ones are easier than traditional ones which are designed with structural language,it can be applied to a large universal computational software for science and engineering.     

Structual Dynamic Characteristics Analysis and Improvement for Two-way Branch Exhaust Pipe Shield

The two-way branch exhaust pipe shield is the main source of surface radiate noise of a vehicle's engine.(Using) the finite element analysis software ANSYS,a finite element model of the shield is established,and then the(modal) analysis is done theoretically with this model,the result is consistent with the experiment.The result shows that this finite element model can be used for the next structual dynamic characteristics analysis.With this model,the relationship of structural parameter,structural style of the shield and the corresponding vibrative modal is analyzed.The(optimal) improved measures are adopted which is based on the practical structure of the shield.The analysis of the(improved) structure shows that the increase of natural vibration frequency is visible,the vibration noise of the shield is suppressed distinctly.     

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.     

植物根系固土作用模型研究进展

植物根系固土作用模型研究已历经近40年,从简单的极限平衡模型到复杂的有限元和离散元数值模型,已发展到10余种。总结这些根系固土作用模型不仅对揭示根系加固土壤作用的力学机制和分析林地边坡的稳定性具有重要意义,对根系固土作用模型未来的研究方向也具有积极指导意义。笔者对根系固土作用模型分2部分进行综述,第一部分主要介绍根系固土作用的理论模型,包括：Wu模型、倾斜根系模型、位移模型、纤维束模型、根束增强模型和能量模型,以及这些模型的应用条件、模型优缺点、适用范围等。第二部分主要综述根系固土作用的数值模型,包括：有限元数值模型、离散元数值模型和造林边坡稳定性分析数值模型,并详细比较了有限元与离散元数值模型的优缺点和在造林边坡稳定性分析上的应用。最后探讨了目前根系固土作用模型研究中存在的不足以及未来的发展方向。     

Lateral Bearing Capacity and Simplified Equations of Dry Stack In filled Reinforcement Concrete Frame Structure

The mechanism and lateral bearing capacity of reinforcement concrete (RC) frame with dry stack in filled panel (DSIP) were investigated using quasi static experiments and finite element models. According to the parallel model and equivalent strut model, the lateral bearing capacity of RC frame and DSIP were researched separately. Results show that: 1) The plain stress element and interface element are applicable in finite element (FE) model analysis. According to the FE model, the failure of RC frame with DSIP is caused by the damage of frame; 2) Lateral bearing capacity of DSIP is mainly from the friction between bricks in the panel, which can be divided into 3 stages: constant stage, increasing stage and ultimate stage; 3) Equations for lateral bearing capacity of DSIP were proposed and verified by FE model results.     

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.     

Intensity Comparative Analysis Based on Ideas Between Involute Gear and Double Involute Gear

Modeler and simulation modules in Ideas software are used to build the finite element models on involute gear and double involute gear with accurate tooth shape, and with the same design parameters and under the same loads, finite element contact analysis has been done. At last, the contact stress and bending stress on the two types gear transmission at the different meshing positions are solved out, and comparative analysis and study have been done. At the same time, that the ladder-shape tooth on the double involute gear how to influence contact stress and bending stress is emphatically analysed. All above offer the theoretical foundation that bring the double involute gear with ladder-shape tooth into the industry.     

The Hysteretic Performance Analysis and Experiment on K-type Overlap Joints of Circular Steel-tubes

Joints are the most important parts of the space structure, the load-derormation curve (hysteretic curve) under repeated loading is the comprehensive reflection of their mechanical properties such as ductility, energy dissipation capacity, strength, stiffness and so on. By the simulation experiment analysis and the finite element simulation between the two models of hidden welding and no-welding hidden in K-type node in the chord axial reciprocating load resulted in the failure modes and hysteretic curve, the result of comparative analysis about finite elements is consistent with that of experiment study. The results show that the destroyment at hidden welding seam node is partly, the take-over is broken down at the welds finally. The welding line is destroyed overall when facing the destroyment of no-welding node. The carrying capacity of the hidden welding is obvious. Through the finite element simulation analysis instead of phase through node hysteretic performance test is feasible.     

Seismic Characteristics of Widened Beam Flange Joints

In order to analyze the seismic behavior of widened beam flange joints, 16 specimens were derived from finite element models base on experiments. The effects of some parameters, such as the increased width and length, on ultimate load and ductility performance of joints were further discussed with ANSYS finite element method. According to specimen failure phenomenon of both experiment and finite element method, the weak link of the joints was found and the cracking possibility was evaluated. A theoretical analysis of the fracture mechanism of widened beam flange connection was conducted. In addition, design method of widened beam flange parameters was introduced, which will offer valuable information and reference for seismic design in steel frame joints.     

Electromagnetic field models and their influences onthe temperature field of large hydro generator

To accurately analyze the loss and heat of large hydro generator,the finite element models of 2D steady state electromagnetic field,moving electromagnetic field and field circuit coupling are established respectively.As an example,the losses of the rotor iron and damper winding of a 36 MW tubular hydro generator are calculated.Furthermore,the influences of 3 different electromagnetic field models on the thermal sources and temperatures are analyzed by 3D finite element calculation of the temperature field.The results are compared with the test data and indicate that the precision of the field circuit coupling model is better.The losses of each damp bar are different and the heat of the damp bar at the lee side is larger than that at the windward with the full load.The maximal temperature of the rotor is located at the damper winding,instead of the field winding.The research is valuable for improving the calculation precision of the rotor losses and temperature field and enhancing the reliability of the hydro generator design and operation.     

Dynamic Characteristics Analysis and Structure Design of Improvement for Exhaust Manifold Cover

The exhaust manifold cover is the main source of surface radiate noise of a 6 360 vehicle's engine.By using the finite element analysis technology,a finite element model of the cover is established,and then the modal analysis is done theoretically with this model,the result is consistent with the experiment.On this basis,the transient response of the cover under the excitation of engine block's vibration is analyzed.The result show that the free edge is the main source of radiate noise,because its normal velocity is maximal.The improved measures are adopted which is based on the practical structure of the cover.The analysis of the improved structure shows that the measures are effective,the radiate noise of the cover is decreased distinctly.     

Generalized conforming quadrilateral membrane element with vertex rotational freedom

A new generalized conforming quadrilateral membrane element is developed by introducing additional rigid vertex rotational freedoms to the normal 4 node quadrilateral membrane element. The rotational stiffness of the present element is not zero so that the singularity of the stiffness matrix is avoided. Numerical analysis of the Cook problem cantilever beam shows that the EAE/Mem element passes the patch test and possesses good convergence, reliability, and precision without a zero energy mode. It provides a lock free solution to the MacNeal beam problem. Numerical results also show that the EAE/Mem element is insensitive to mesh distortion. The results demonstrate that the generalized conforming technique is an efficient tool for developing high performance finite element models.     

Constant Scallop-height tool-path Planning for Surface Interpolation and the Evaluation of Errors

The calculative precision of the cutting breadth has a significant effect on the machining precision and the machining efficiency for free-form surface machining. For traditional arithmetic, there are two oppositional approaches to calculate the path interval. One approach is very simple, but its veracity is not enough for complex surface. The other approach is very complicated, so its calculative efficiency is low. A new approach is presented to calculate the path interval. A spline of circle is adopted to approach the transversal of surface. Then the arithmetic based on the spline is proposed to calculate the path interval. In the proposed methodology, the calculative efficiency is fully improved on the condition of meeting the need of machining precision. Furthermore, the algorithm''s time needed by calculating path interval is steady. So it is suitable for periodic interpolation. Two study cases verify the applicability of this new approach of Constant Scallop-height tool-path planning.     

Numerical simulation of remodeling in mandible under orthopedic loads

The research on the remodeling in mandible under the action of orthopedic loads is important for the determination of orthopedic scheme. a three-dimensional finite element model of mandible and temporomandibular joint is established. Using Cowin Remodeling Law, the finite element simulation of the remodeling in mandible during the orthopedics under the action of orthopedic loads is carried out. Comparing the numerical results after remodeling with those before remodeling, it is demonstrated that the normal remodeling greatly affects the distribution of strain and strain gradient on the surface, therefore the effect cannot be ignored in the determination of the orthopedic scheme.     

多点锚固预应力CFRP带加固T梁的有限元分析

采用非线性有限元分析程序ABAQUS对无粘结体外预应力CFRP片材加固简支钢筋混凝土T形梁后进行数值模拟,该模拟梁共4根分别为3根梁侧对称加固,1根为梁底加固均为四点波形齿锚固预应力CFRP带。对比结果显示,数据模拟与试验结果在构件屈服以前的承载力、变形以及极限承载力吻合程度较好,构件屈服以后的变形差别较大,因此,可在一定程度上有效替代试验分析方法。依据吻合程度最好的TL3参数设计了“两点锚固”和“四点锚固”的模型进行模拟分析。通过对锚固点数及加固量改变的对比分析可知,依据加固构件的弯矩改变各段加固量及布置锚固点数的方法既可以保证加固效果不降低,又可以节约CFRP材料。     

A Comparative Study of Confined Concrete Models under Cyclic Loading

In this paper,four models are selected as the representatives and applied to nonlinear dynamic analysis program for space frames which is based on the beam-column elements using the finite element flexibility method and the fiber model.Park's test on combined axial and bending columns under cyclic loading are taken as the calibrations,comparisons to material and structural member level are drawn and the analytical results of various models are discussed.     

Effects of Spherical Joint Stiffness on Seismic Response of Single-Layer Cylindrical Reticulated Shell Changing with Peak Ground Acceleration

The previous studies find that the hollow spherical joint stiffness has a certain influence on seismic response of single-layer cylindrical reticulated shell. In order to analyze the rule of this influence with PGA (peak ground acceleration) changing, two types of finite element models are built. The two types of models have the same size except the spherical joint. The first type is a fine model built by shell element and its spherical joints and tubes are built by considering the real size; the other type is the common model which is built by beam element, and the spherical joints are neglected. Comparing with the seismic response of the two types of models when PGA changes, the results show the difference between the two types of model in node displacement-time curves is increased as PGA increases; when the PGA is larger than the collapse acceleration of structure, the influence of increasing joint wall thickness on improving the structural capacity of anti-stability is decreased as PGA increases.     

THE SPLINE BOUNDARY ELEMENT METHOD FOR CALCULATION OF ELECTROMAGNETIC FIELD PROBLEMS

The spline boundary element method is presented for electromagnetic field problems. Based on B-spline function interpolation, the formulation of calculation of two dimensional statical electromagnetic field problems is obtained. Boundary corner and singular integration problems are efficiently handled. Furthermore,the Method is used for solving two calculation examples.