CAE技术系列应用案例(3)——大连重工CAE技术系列应用案例

(四)门座架钢结构的有限元计算和优化 1.力学模型 门座架钢结构也是堆取料机的主要部件,悬臂梁钢结构、俯仰钢结构和回转钢结构均由它来支撑,因此它的强度和刚度至关重要。图1给出了三腿支撑的门座架的网格图,图2给出了四腿支撑的门座架的网格图。本文我们着重研究三腿支撑的门座架。

Design of Finite Element Tools for Coupled Surface and Volume Meshes

Many problems with underlying variational structure involve a coupling of volume with surface effects.A straight-forward approach in a finite element discretiza- tion is to make use of the surface triangulation that is naturally induced by the volume triangulation.In an adaptive method one wants to facilitate'matching'local mesh modifications,i.e.,local refinement and/or coarsening,of volume and surface mesh with standard tools such that the surface grid is always induced by the volume grid. We describe the concepts behind this approach for bisectional refinement and describe new tools incorporated in the finite element toolbox ALBERTA.We also present several important applications of the mesh coupling.

Seismic Techniques for Surveying the Underground of Shallow Foundations

For civil structures founded on shallow foundations, the ground underneath the foundation often holds the greatest risks of the total structure. This can be due to of a very soft soil layer, an inhomogeneous subsurface or a hidden dangerous object. It would be most favorable when a cheap and quick kind of seismic ＂tap-and-listen＂ technique can be used to detect those risks. The problem is however that an applied pulse or blast always creates a combination of compression-, shear- and surface-waves. These types of waves have different wave velocities and will return therefore at different time intervals. For a shallow subsurface technique, all these waves will overlap, which makes the interpretation very hard. Both the single pulse technique and the single-frequency, multiple wave technique （constant vibration） have been studied, but both techniques have their limitations. It can be concluded from finite element calculations that it will be difficult or even impossible to design good seismic techniques for surveying the underground of shallow foundations for hidden shallow potholes, etc.. The main reason is that the relative amount still present original wave. objects like water pipelines, undetonated bombs, dead bodies, coffins, of reflected energy is simply too low in comparison to the energy of the

Modeling of Earth Magnetic Field Disturbances Induced by Ferromagnetic Objects

This paper presents the methodology and results of modelling of Earth magnetic field disturbances induced by ferromagnetic objects. The modeling was carried out using the finite elements calculations, and the results were compared with the measurements. The special test stand, consisting of magnetovision scanner and Helmholtz coils, has been used. The measurement system is able to measure the distribution of planar magnetic induction vectors, and to differentiate the sources of measured disturbances.

Numerical Analysis of a Blocking Mass Attenuating Wave Propagation

Based on wave theory, blocking mass impeding propagation of flexural waves was analyzed with force excitation applied on a ship pedestal. The analysis model of a complex structure was developed by combining statistical energy analysis and the finite element method. Based on the hybrid FE-SEA method, the vibro-acoustic response of a complex structure was solved. Then, the sound radiation of a cylindrical shell model influenced by blocking mass was calculated in mid/high frequency. The result shows that blocking mass has an obvious effect on impeding propagation. The study provides a theoretical and experimental basis for application of the blocking mass to structure-borne sound propagation control.

Multi-objective optimization of crimping of large-diameter welding pipe

Crimping is widely adopted in the production of large-diameter submerged-arc welding pipes. Traditionally, designers obtain the technical parameters for crimping from experience or by trial and error through experiments and the finite element(FE) method. However, it is difficult to achieve ideal crimping quality by these approaches. To resolve this issue, crimping parameter design was investigated by multi-objective optimization. Crimping was simulated using the FE code ABAQUS and the FE model was validated experimentally. A welding pipe made of X80 high-strength pipeline steel was considered as a target object and the optimization problem for its crimping was formulated as a mathematical model and crimping was optimized. A response surface method based on the radial basis function was used to construct a surrogate model; the genetic algorithm NSGA-II was adopted to search for Pareto solutions; grey relational analysis was used to determine the most satisfactory solution from the Pareto solutions. The obtained optimal design of parameters shows good agreement with the initial design and remarkably improves the crimping quality. Thus, the results provide an effective approach for improving crimping quality and reducing design times.

Design and Optimization of Index-Guiding Photonic Crystal Fiber Gas Sensor

An index guiding photonic crystal fiber used in gas sensing applications is presented. The dependency of the confinement loss and relative sensitivity on the fiber parameters and wavelength is numerically investigated by using the full-vectorial finite element method （FEM）. The simulations showed that the gas sensing sensitivity increased with an increase in the core diameter and a decrease in the distance between centers of two adjacent holes. Increasing the hole size of two outer cladding rings, this structure simultaneously showed up to 10% improved sensitivity, and the confinement loss reached 6x 10-4 times less than that of the prior sensor at the wavelength of 1.5 μm. This proved the ability of this fiber used in gas and chemicals sensing applications.

Multivariable wavelet finite element for flexible skew thin plate analysis

Flexible skew thin plate is widely used in mechanical engineering,architectural engineering and structural engineering.High-precision analysis is very important for structural design and improvement.In this paper,the multivariable wavelet finite element(MWFE)based on B-spline wavelet on the interval(BSWI)is constructed for flexible skew thin plate analysis.First,the finite element formulation is derived from multivariable generalized potential energy function.Then the generalized field variables are interpolated and calculated by BSWI.Different from the traditional wavelet finite element,the analysis precision can be improved because the generalized displacement and stress field variables are interpolated and calculated independently,the secondary calculation and the computational error are avoided.In order to verify the effectiveness of the constructed MWFE,several numerical examples are given in the end.

Structural bionic design for high-speed machine tool working table based on distribution rules of leaf veins

High-speed machine tool working table restrains the machining accuracy and machining efficiency,so lightweight design of the table is an important issue.In nature,leaf has developed a plate structure that maximizes the surface-to-volume ratio.It can be seen as a plate structure stiffened by veins.Compared with a high-speed machine tool working table,leaf veins play a role of supporting part which is similar to that of stiffening ribs,and they can provide some new design ideas for lightweight design of the table.In this paper,distribution rules of leaf veins were investigated,and a structural bionic design for the table was achieved based on regulation of leaf veins.First,statistical analysis on geometric structure of leaf veins was carried out,and four distribution rules were obtained.Then,relevant mechanical models were developed and analyzed in finite element software.Based on the results from mechanical analysis on those relevant models,the four distribution rules were translated into the design rules and a structural bionic design for the working table was achieved.Both simulation and experimental verifications were carried out,and results showed that the average displacement of the working table was reduced by about 33.9%.