Three-dimensional CAD Systems Research Articles

Intelligent Systems for the Prognosis of Energy Consumption in Manufacturing and Assembly

This paper is based on a current research project and describes methods which aim to contribute to the estimation of the energy consumption in the production of goods. Today, the energy a product requires during its operation is the object of many activities in research and development. However, the energy necessary for the production of goods is very often not analyzed in comparable depth. The energy consumption in production and disposal is determined very early in the product development process by designers and engineers, for example, through selection of raw materials, explicit and implicit requirements concerning the manufacturing and assembly processes or through decisions concerning the product architecture. Today, developers and engineers have at their disposal manifold design and simulation tools, which can help to predict the energy consumption during operation relatively accurately. In contrast, tools with the objective to predict the energy consumption in production and disposal are not available apart from the first material databases, such as Eco Materials Adviser in Autodesk.Calculations of the energy consumption in the production can be based on certain volumes and/or the weights of the components or of certain sections of the components. For example, the milling volume for milling operations can be used to determine the energy necessary for this milling operation. Research in production technology can these days provide the necessary tables and equations to determine this energy, if only the milling volume and the milling operations are defined accurately enough. The geometry is developed today almost exclusively in three-dimensional CAD systems. In such systems, the volumes and weights of all components are available today; therefore, the extension is very promising to couple future systems with CAD systems.

Research and Development of Steel Casting CAD/CAE Integration Technology Based on the Neutral STEP File

The casting process CAD system developed based on the existing three-dimensional CAD software has many inadequacies. This paper innovatively puts forward the steel castings three-dimensional casting process CAD system based on neutral STEP file. In this study, by taking advantage of universal CAD data-exchange standard STEP format for data exchange, a practical three-dimensional CAD system was developed based on Open CASCADE Geometry Kernel. The system has the function of practical casting process modeling, including design and modeling of gating system and riser design and so forth. The system exceeded the deficiencies of the existing casting process CAD system. It resolves the foundry Enterprises dependence and limitations on the type and version of commercial 3D CAD software, enabling to realizethe integration of CAD and CAE on casting process.

The Algorithm Research on Adaptive Tooth Height Modeling Modification Based on PRO-E

Three-dimensional CAD system is designed by using PRO-E tools. In particular, gear model has been widely used. The usual design philosophy is to perform parametric modeling based on different gears, find the relationship between different parameters, make use of restrictive relationship between different parameters, and complete its modeling process. In this paper, on the basis of this concept, the amount of modification is adaptively determined according to the actual conditions of the operational test situation in actual working conditions, and model modification lengths are optimized in which the amount of model modifications can all be allocated in the active or passive wheel sprocket teeth, and can also be modified both in active and passive wheel. Model modifications are done only in double tooth meshing zone and the gradually open lines in single tooth meshing zone are not modified to ultimately achieve the purpose of gear model optimizing.

Study on Statistical Method of Steel Bridge Parts Information Based on Three-Dimensional CAD

Parts information of steel bridge with tens of thousands of parts is difficult to be managed and be executed statistics. On the platform of three-dimensional CAD systems, steel bridge node is the study object in this paper, according to the assembly relationship of all parts in the three-dimensional assembly model, the parts list, quantity, geometrical information and weight of the parts of the steel bridge nodes are extracted from a three-dimensional model by the application interface provided by three-dimensional CAD systems. On the basis of geometrical information of the parts, the minimum boundary dimension of the parts is computed by use of the principle of computer graphics. The method can rapidly and accurately obtain parts information, and can provide basis for assembly process and processing technology.

Development of CAD System Based on Function Features

Three-dimensional CAD systems contribute considerably to the detailed design processes of products. They are applied to the construction of 3D design models which are also utilized for design evaluation using a CAE system and for NC data generation using a CAM system. Since the functions of 3D CAD systems for constructing 3D models are increasingly being enhanced, they enable designers to easily construct 3D product models without design expertise. In detailed design work, designers are required not only to exactly define product shapes but also to assign attribute information such as dimensional tolerance, geometrical tolerance, roughness, machining process to be performed etc., which are essential for the manufacturing process. However, inexperienced designers often find it extremely hard to determine optimum attribute values and design values. In addition, it is more difficult to construct the required die/mold from the desired product shape taking into account forming errors caused by shrinkage during plastic injection and springback during press forming. This paper proposes a method to automatically assign required attribute information to each part of a designed product, to assist the model construction of a die/mold from a product shape, and to provide design support information on each part of a designed product to a designer. The proposed method is realized by assigning a Function Feature to each part; all the function features proposed in this paper are original. A CAD system based on the proposed method for injection molding and press forming was developed, and results of simple design experiments confirmed the usefulness of the CAD system and function features

Knowledge-based approach to flexible part design

Virtual prototyping (VP) of complex machines requires the realistic representation of components to perform robust analyses and simulations. In many cases, machines are an assembly of rigid and flexible components. Although modern three-dimensional CAD systems can be considered powerful tools for modelling solids or surfaces representing rigid bodies, they are not adequate to model soft material components, especially a realistic visualisation of physical behaviour. This drawback motivated the present research work. In particular, this paper describes an approach and the related knowledge-based software system (FlexSim) developed to create virtual prototypes facilitating product development in cases of flexible parts like cables, pipes and wires. The resulting VP tool integrates the CAD technology and the dedicated structural simulation methods to automatically model and validate three-dimensional functional sub-groups having flexible parts. The system application is shown on metallic reinforced elastomer hoses used for hydraulic power transmissions. For this purpose, a finite-element approach has been implemented to find hose configurations for given boundary conditions determined by mounting positions. Pipe fittings are selected and automatically assembled and the optimal hose length and its ideal spatial disposition are calculated. Simulations of behaviour allow the rapid optimisation of a solution. The system has been tested on agricultural harvest machines and mining equipment, which widely employ hydraulic transmissions for moving groups of components. As a result, the number of physical prototypes, the lead-time due to the trial-and-error activities and the product development costs can be significantly reduced.

Feature-based multiresolution modeling of solids

Recently, three-dimensional CAD systems based on feature-based solid modeling techniques have been widely used for product design. However, when part models associated with features are used in various downstream applications, simplified models at various levels of detail (LODs) are frequently more desirable than the full details of the parts. One challenge is to generate valid models at various LODs after an arbitrary rearrangement of features using a certain LOD criterion, because composite Boolean operations consisting of union and subtraction are not commutative. This article proposes an algorithm for feature-based multiresolution solid modeling based on the effective volumes of features. This algorithm guarantees the same resulting shape and the reasonable intermediate LOD models for an arbitrary rearrangement of the features, regardless of whether feature types are additive or subtractive. This characteristic enables various LOD criteria to be used for a wide range of applications including computer-aided design and analysis.

533 動作計測を利用した3DCADシステムの開発(S05-2 次世代CAD/CAE (2),S05 次世代CAD/CAE)

In this study, a three-dimensional CAD system for free-formed modeling was developed. Operation postures were recognized using digital motion-caputuring system and were reflected the modeling manupulation under the virtual environments. FE modeling for a couple of femural and tibial bone was tried for the application of biomechanical simulation. Some human interfaces and the graphical routines were utilized effectively to emulate the medical operations and to enhance intuitive ones. The alignement of the femur, tibial, and artifial protheses of FE model were possible easily compared with the traditional CAD/CAE systems.

Multi-Resolution Modelling for Feature-Based Solid Models Using the Effective Volumes of Features

AbstractRecently, three-dimensional CAD systems based on feature-based solid modelling techniques have been widely used for product design. However, when part models associated with features are used in various downstream applications, simplified models at various levels of detail (LODs) are frequently more desirable than the full details of the parts. One challenge is to generate valid models at various LODs after an arbitrary rearrangement of features using to a certain LOD criterion, because composite Boolean operations consisting of union and subtraction are not commutative. This paper proposes an algorithm for feature-based multi-resolution modelling based on the effective volumes of features. This algorithm guarantees the same resulting shape and the reasonable intermediate LOD models for an arbitrary rearrangement of the features, regardless of whether feature types are additive or subtractive. This characteristic enables various LOD criteria to be used for a wide range of applications.

人工関節置換に対応した三次元CADシステムの研究(J03 CAD/CAE,J03 次世代のCAD/CAE)

In this study, a three-dimensional CAD system for biomechanical simulations was developed. Some human interfaces and the graphical routines were utilized effectively to emulate the medical operations and to enhance intuitive ones. A pair of the knee joint finite element model was used to evaluate the performance of this system. The replacement of the artifial joint and the control of the insertion direction of the prothesis were possible easily compared with the traditional CAD systems.

Development of a Support System for Mechanical Parts Standardization. 1st Report. Standardization of Mechanical Parts by Using Macro Function.

It is very important to standardize mechanical parts as productivity increases. But, this is a very difficult subject, because there are a lot of kinds of different mechanical parts, and the mechanical parts are very complicated. Therefore, we have developed a support system, which standardizes the mechanical parts. The mechanical parts can divide into several components, and it is relatively easy to standardize these components. We built an individual standardization data base for each component, and link these data bases into a system. The system used a macro function, which records a series of operations of three-dimensional CAD system. This paper describes the methods for standardizing the mechanical parts by the macro function, with an emphasis on the method for building the standardization data base automatically, the method for generating a frame of input and output formats, and so on.

CAD for free-form surfaces

Recently, consumer products with complex idiosyncratic curved surfaces are becoming increasingly common in the market. It is now usual for designers of products such as cars and consumer electronic goods to use free-form surfaces that cannot be adequately represented in two-dimensional drawings. As a result, computers, especially three-dimensional CAD systems, have become essential design tools. Unfortunately, 3D CAD systems are still regarded as impossibly complicated by many designers. To address this problem, we have developed a 3D CAD system that makes it easy for designers to interactively create and modify the shapes that they have in mind. This system features high-quality modelling functions, can also produce rendered views of the models it generates, and incorporates a user-friendly interface that allows the designer to operate the system unaided. Compared to conventional design processes based on 2D drawings and fabrication of the mock-up products, this system provides an environment that can make great contributions to design work. This paper describes the functions and features of the system.

Development of Sketching System of Porcelain Using Slit-Light Method.

We have developed a system for automatically sketching patterns on the surface of porcelain using a Slit-light method which is one type of three-dimensional image measurement. This system has two parts. One is a measurement system of the three-dimensional shape of porcelain piece, and the other is an automatical sketching system of patterns by using the result of three-dimensional measurement. Since we classified porcelain pieces into two types according to their shape, two three-dimensional measurement systems were developed. In these measurement systems, we proposed a calibration method using bilinear interpolation in order to calculate values of three-dimensional coordinates simply and speedily. This calibration could absorb errors such as lens distortion and mechanical errors. The automatical sketching system was realized by linking three-dimensional measurement systems and a three-dimensional CAD system.

Automatic Large-Scale Mesh Genearation Based on Fuzzy Knowledge Processing and Computational Geometry. Its Application to Two-Dimensional Plane, Three-Dimensional Solid and Three-Dimensional Shell.

This paper describes a novel automatic finite-element mesh generation method for large-scale complex structures based on fuzzy knowledge processing and computational geometry. Its mesh generation process consists of three main subprocesses: ( a ) : definition of an analysis domain, ( b )generation of nodes, and ( c ) generation of elements. Practical three-dimensional CAD systems for three-dimensional solids and shells are employed for subprocess ( a ) . In subprocess ( b ), nodal densities of locally optimum nodal patterns are first chosen from the nodal pattern database of the system, and secondly these nodal densities are superposed on one another by using fuzzy knowledge processing. Thirdly, nodes are generated by the bucket method, whose processing speed is almost proportional to the number of total nodes. In subprocess ( c ), either triangular or tetrahedral elements are generated in a two-or three-dimensional domain, respectively, using the Delaunay triangulation whose speed is also proportional to the number of total nodes. In the cases of two-dimensional plane and three-dimensional shell, triangles can be converted into quadrilaterals. To demonstrate the practical performance of the present method, it is applied to mesh generation of a nozzle corner of a nuclear pressure vessel, and that of a portion of an automobile body.

Automatic paper pattern making using mechanical development method of a curved surface on a plane surface.

We developed a three-dimensional apparel CAD system which simulated draping and sample making processes. In this paper, we explain the draping system. Usually draping means a technique of making paper patterns by draping a cloth around a dummy. It is difficult to simulate the process directly. So, we separate the process into two sub-processes. The first process is to generate three-dimensional shapes of garments or to measure the shape of a human body. The second process is to develop the three-dimensional surface on a plane surface. Here we focus on the technique of the second process. The technique is based on a mechanical calculation using a finite element method. The system consists of the following sub-programs. 1) Input a three-dimensional curved surface. 2) Input the mechanical properties of material fabrics. 3) Input the indication of the area to flatten. 4) Input the boundary conditions. 5) Divide the area into the triangular elements. 6) Make an initial plane surface. 7) Calculate the plane surface which is best fitted to the three-dimensional surface. 8) Output the best fitted plane paper pattern. 9) Output the strain and stress distributions where the plane surface coincides with the threedimensional surface. Using this system, we can obtain the best fitted paper pattern. The stress and strain distributions are used to evaluate the paper patterns. When a three-dimensional curved surface is fixed, we can obtain many paper patterns according to the mechanical properties of material fabrics and locations of darts. Finally we give an example to show that this system is applicable to a real problem.

Computer-aided design applications on microcomputers

A microcomputer-based, two-dimensional CAD system has been developed and implemented for a specific manufacturing environment, namely, the small manufacturer. This work began with a system for the design of multiple-spindle drill heads. A subset of Lockheed's CADAM system was emulated on a microcomputer to demonstrate the feasibility of this approach. Facilities were provided for drawing and erasing points, lines, and circles; relimiting and cornering; offsetting; windowing; and filing. CADAM's user interface was provided with a vertical menu, function keys, prompts, and color highlighting. A brief overview is also presented of system specifications and capabilities of a full-function three-dimensional CAD system for IBM PC microcomputers.