System Supporting Automatic Generation of Finite Element Using Image Information

A mesh generating system has been developed in orde r to prepare large amounts of input data which are needed for easy implementation of a finite element analysis. This system consists of a Pre-Mesh Generator, an Automatic Mesh Generator and a Mesh Modifier. Pre-Mesh Generator produces the shape and sub-block information as input data of Automatic Mesh Generator by c arrying out various image processing with respect to the image information of th e drawing input using scanner. Automatic Mesh Generator generates mesh of trian gular elements in the arbitrarily shaped and multiple connected planar domain by using minimum necessary information. This generator has 3 methods of mesh gene ration for each sub-block, A) Regular Mesh Generation, B) Semi-Regular Mesh Ge neration and C) Irregular Mesh Generation. Any of them can be selected automati cally according to the external form of sub-block or the state of domain. Mesh Modifier projects and modifies the pattern of generated mesh by Automatic Mesh Generator as required. This system simplifies the user’s task while saving manp ower in carrying out the finite element analysis.

FOURTH-ORDER ACCURATE DIFFERENCE METHOD FOR THE SINGULAR PERTURBATION PROBLEM

In this paper, the numerical solution of fourth-order ordinary differential equations is considered. To approximate the differential equation, the Hermitian scheme on a special nonequidistant mesh is used. The fourth-order convergence uniform in the perturbation parameter is proved. The numerical result shows the pointwise convergence, too.

Tensile Structures of Cables Net, Guidelines to Design and Applications

The structural engineering design of not conventional typologies imposes a complex path that begins evaluating procedures of a preliminary design and ends with complex procedures to validate the analysis response. Any guide lines to follow are often available. About complex shapes, in particular, any details are presented in the codes to evaluate wind action and so wind tunnel experiments are necessary to valuate this. The evaluation of wind tunnel data is a complex process that often needs new and specific subroutines programmed by researchers. The difficult increases when the objective is to study a not specific building but general aspects as for examples the dependence of a generic phenomenon by a geometric sample;in this case it is necessary to design and to program numerical subroutines before and then the wind tunnel experiments. Often, these subroutines are left detached and are non-generalizable process. Purpose of this paper is to describe a complete procedure to pre- and post-process wind tunnel data with the objective to design a not convectional structure as a tensile structure. In this particular case the research aim is a parametrization of the aerodynamic behavior of Hyperbolic Paraboloid roofs, shape used for cables net. The reason of the experiments is the absence in the international codes of the pressure coefficients for these geometries. The paper describes the numerical procedure evaluated to choose a sufficient representative geometric sample, the numerical procedure evaluated to design and to construct the wind tunnel models and FE models, the numerical procedure to evaluate and to use for FEM analyses of the wind tunnel data, the numerical procedure to calculate nonlinear structural analysis, and, finally some applications. All these numerical procedures use basic theory derived for example by the cable theory, the fluid mechanic, the nonlinear geometric analysis and other. However specific codes were necessary and were programmed to apply the theories on the specific case of study;the complete methodology followed is presented. The goal is to create a free open domain where the numerical procedures evaluated are merged, added, modified by researchers with the aim to obtain a common space of use for wind engineering of not conventional structure.