Shinji Tokumasu

An Automated Finite Polygon Division Method for 3-D Objects

The automatic generation of color-shading data for CAD/CAM objects can produce mass-property calculations in less time with fewer errors.

Feature-based heuristics for finite-element meshing using quadtrees and octrees

Abstract The paper discusses a mesh-generation technique, and presents product-model applications for computer-aided engineering using a supercomputer. The analysis procedure is automated by mesh generation and feature descriptions in the product model. The mesh-generation technique uses the feature descriptions to obtain a well controlled mesh density. Some practical examples are given that are calculated by the HITAC S-810 supercomputer.

Solid Model in Geometric Modelling System : HICAD

The geometric modelling system plays an important role in CAD for the mechanical engineering. This paper presents the general purposed conversational geometric modelling, HICAD which has been developed to confirm the integrated CAD. The HICAD is a generalized geometric model which includes three of the typical geometric modellings, i.e., the wire frame, surface, and solid models. Herein, the implementation method of solid model is especially discussed with the summary of whole system.

Implementation of Geometric Modelling System: HICAD

The geometric modelling defines a figure to a computer with structural descriptions. It is connotatively a technique of graphical operation, and denotatively a method to define figures in CAD/CAM technology. The structural description is to give a basic expression of a figure, and to define the internal expression which refers to the external figure. In order to accomplish this systematical approach, the structural description has to be systematically existed in computer, and the established system is so called geometric modelling system or geometric modeller. It is obvious that the process of CAD/CAM and graphical operation will be subjected to a modeller also whether a successful result is confirmed or not. It is why a modeller becomes such important to be considered. The first, it has difficulties to work on a system development for the present Neumann Computer. The difficulties are induced from the character of the machine that it recognizes objects in blind. Seconderly, it is almost impossible to consider most problems without knowing of the figure of the object in CAD/CAM (or applied numerical analysis). It is reasonable way to think that the application of computer is depended upon to obtain the efficient internal expression of the objected figure on the drafting procedures, the analyses of the performance, and the informating procedures for N.C. formulation, since our products exists on three—dimensional space.

Spanning a C1‐Surface over a Given Wireframe

A problem of spanning a surface of C1 continuity (C1‐surface) over a given wireframe is introduced. By exploiting the concept of a super surface patch introduced in an earlier paper, we proved the existence of an approximate, yet practical solution of the problem. That is, we presented a method or a procedure, by which to span a C1‐surface over the wireframe. This technique is intended to be utilized as a flexible surface generation method for the 3D shape design in the industrial world.

Quantitative Constitutive Equation for Face Centered Cubic Crystals Based on Dislocation Dynamics Model

In many fields concerning the strength of materials, we have to know the micro-mechanical processes in deforming bodies. For this, a lot of studies have been done on the constitutive equations of materials which describe the stress-strain relation of bodies, and their application to engineering problems [NematNasser(1981)]. Despite their completeness in mathematical form, there is still a lack of clear description for elementary process of deformation such as the movement of dislocations. On the other hand, the theories of discrete or continuously distributed dislocations [Mura(1969)] have succeeded to express the deformation process in a microscopic region, such as the one near a crack tip, assuming rather simple distribution of dislocations. But the application to the body with macroscopic dimension is extremely restricted since we can seldom prescribe the extent of plastic zone precisely.