Heterogeneous CAD Research Articles

Research on method of constraint conversion in feature-based data exchange between heterogeneous CAD systems

Data exchange between heterogeneous CAD systems is the key problem in the field of CAD, and the popular solution to this problem is a feature-based method. Aiming at keeping the consistency of design intent in data exchange between heterogeneous CAD systems, this research focuses on the method of constraint conversion. First, two kinds of basic feature transformation ways are summarized, and this is the foundation of constraint conversion. Second, a novel identification of geometric elements based on the improved geometric certificate is proposed, and the identifier of geometric element is used to recognize the acting object of constraint. Third, the principles of constraint conversion are put forward, and the method of constraint conversion for a single feature is proposed according to the principles. Fourth, an algorithm of constraint conversion for the whole process of CAD data exchange is designed. Finally, the contrast experiment of CAD data exchange is completed, and the result of the experiment shows that the approach mentioned above is effective.

Synthesis of the digital mock-up system for heterogeneous CAD assembly

Many collaborators are involved in design processes of cars, ships, aircrafts, machine tools, etc. Instead of a single CAD source, several CAD systems are used to design such complex products in the distributed design environment. There are many mismatches and interferences due to designers’ faults as well as several kinds of CAD systems. Digital mock-up (DMU) system, a tool to build a virtual mock-up in the design stage, has been used to prevent the interferences and mismatches during precision design processes. In this paper, a heterogeneous CAD assembly method to construct the DMU system is proposed through an XML and the lightweight CAD file. The XML data contain hierarchy of heterogeneous CAD assemblies. STEP PDM schema is applied to construct the XML data. The lightweight CAD file produced from a CAD file through ACIS kernel and InterOp includes not only mesh and B-Rep data, but also topological data. They are used to visualize CAD data and to verify dimensions of the parts. Developed system is executable on a desktop computer. It does not require commercial CAD systems to visualize 3D assembly data. Assembly of heterogeneous CAD models has been conducted to verify the effectiveness of the developed DMU system on the Internet.

Constraint Conversion Method in Feature-Based Heterogeneous CAD Model Exchange

Constraint Conversion Method in Feature-Based Heterogeneous CAD Model Exchange

Integration of product data management and CAD systems by Java-COM bridge

An object-oriented product information model is established for extraction of product data from a CAD system so that an integrated interface can be built to achieve integration between heterogeneous product data management and CAD systems. An interface program is developed by combining Java-Com bridge and COM to achieve real-time data exchange without using neutral files. An automatic product structure tree building algorithm is proposed to store data in an organised way in a product data management system, and a dead-cycle detection algorithm is proposed to keep the input defect-free. The trial operations of the newly developed system indicate that the approach is effective for integrating of product data management and CAD systems for real-time data exchange.

Synchronised collaborative design between heterogeneous CAD systems based on web service

An approach to construct a synchronised collaborative design platform upon heterogeneous CAD systems based on client-server architecture is presented in this paper. In the approach, the Neuter Feature Set (NFS), which is defined by object oriented representation, is utilised as an intermediate to achieve synchronised exchange of feature-based CAD models between heterogeneous CAD systems. Before achieving this goal, persistent naming of topological entity must have proper solution. A hybrid topological entity naming mechanism is proposed in this paper. Furthermore, in order to extend the system to web services and application integrating environments, central transfer functionality and components are identified. XML is chosen as the most suitable technology and physical transfer format, and a corresponding functional concept is developed for model processing, transcription and CAD interfacing.

Data Transfer from Heterogeneous CAD to Division Mockup Virtual Prototype

Virtual prototype technology could integrate different CAD formats parts into an digital model. In this way the design process will be more efficient. This issue reviewed three methods to transfer data from CAD parts to virtual reality element. And find an efficient way to transfer different CAD model data to virtual prototype software Division MockUp.

A method and tool for human–human interaction and instant collaboration in CSCW-based CAD

From human–computer interaction to human–human interaction and from information sharing to instant collaboration are major advances from traditional standalone and distributed CAD to collaborative CAD. This paper explores model, method and tool to achieve this goal. A human-centered collaborative design model to support human–human interaction is presented. A method to transparently add aware capabilities to single-user CAD applications is outlined. Based on the method, an instant collaboration tool is implemented to support human–human interaction in collaborative design process. The collaboration tool involved some core collaborative issues such as agent structure, communication, group awareness, consistency maintenance and collaborative tasks. We also test the method in a 3D collaborative tool for heterogeneous CAD applications.

Digital exchange of design models between marine equipment libraries using hybrid neutral formats

The selection of marine equipment is a time-consuming process for a ship outfitting designer. The inefficiency originates from the paper-based exchange of design information between shipyards and equipment manufacturers. We propose a method to exchange equipment models for electronic commerce. Shipyard practices were investigated to find out how the outfitting CAD library is being used. We also surveyed international standards for the exchange of digital equipment models, and analyzed the macroparametric methodology. We propose a hybrid method to represent the geometric information using STEP AP203 or the macroparametric method. The nongeometric information is defined according to the Parts Library (PLIB) standard. We implement a pilot system and test it with a ship design data set. The equipment model proposed can be used in the design process with heterogeneous shipbuilding CAD systems. The equipment model can improve the design and purchase process in shipyards.

A processing algorithm for freeform fabrication of heterogeneous structures

A processing algorithm for freeform fabrication of heterogeneous structures is presented. The algorithm was developed based on the heterogeneous fabrication structural model, which was constructed from the STL based multi‐material volume regions and with material identifications. The reasoning Boolean operation based modelling approach was used to construct the heterogeneous CAD assembly and to output the needed STL format. Procedures for generating the database hierarchy and the storage of the heterogeneous structural model, and derivation for developing the processing algorithm for layered fabrication of heterogeneous structure are presented. The developed algorithm was applied to a heterogeneous structure consisting of two discrete material volumes, and the detailed processing path is described.

Manipulating Geometry in a STEP DB from Commercial CAD Systems

It is difficult to access and share design data among heterogeneous CAD systems. Usually different CAD systems exchange design data using a neutral format such as IGES or STEP. A prototype STEP database has been implemented. The prototype system uses the OpenCascade geometric kernel and the commercial object-oriented database ObjectStore. STEP provides the database schema. The STEP database has been accessed and manipulated from commercial CAD systems of SolidWorks and Unigraphics. The data access module of the commercial CAD system has been developed by using the CAD system’s native API, ObjectStore API, and ActiveX.

Representation and Visualization for Heterogeneous CAD models

Computer-Aided Design and Applications is an international journal on the applications of CAD and CAM. It publishes papers in the general domain of CAD plus in emerging fields like bio-CAD, nano-CAD, soft-CAD, garment-CAD, PLM, PDM, CAD data mining, CAD and the internet, CAD education, genetic algorithms and CAD engines. The journal is aimed at all developers and users of CAD technology to ptovide CAD solutions for various stages of design and manufacturing. The journal publishes all about Computer-Aided Design and Computer-Aided technologies.

Mapping product structures between CAD and PDM systems using UML

The product data exchange between heterogeneous CAD and PDM systems is a crucial issue for the integration of product development systems. STEP offers an efficient mechanism of product data exchange between heterogeneous systems. This paper introduces a UML-based mapping methodology for the product data models. The suggested mapping method has been applied to exchange the product structure data between a CAD system and a PDM system. Based on the STEP methods, we developed an interface module.

Data enhancement for sharing of ship design models

Within a shipyard, many designers each having their own design objective cooperate in a complex design situation where a variety of software tools run on different hardware platforms. The exchange of design data models among these heterogeneous CAD systems is a difficult task because the systems involved have different data structures optimized for their own functions. CAD geometric models are represented by different schemes such as 2D graphic entities, 3D wireframe, 3D surface model, and solid B-Rep/CSG model. A data exchange usually requires topological modifications of CAD data. This paper presents a strategy of CAD data enhancement for the purpose of data exchange that includes topological changes of geometric models. As a practical example, a shipbuilding product model with shipbuilding features is implemented according to the STEP methodology. Its geometric data is enhanced through a non-manifold modeler to a data set valuable to downstream applications such as a FEM solver or a detail design system. The ACIS modeler that supports a non-manifold data structure is used for low-level geometric operations.

A new methodology for recognizing features in rotational parts using STEP data exchange standard

Automated feature recognition is considered a critical node for integration of CAD/CAPP/CAM. The CAPP module requires the implementation of a feature recognition procedure, so that decisions relating to steps of process planning activities can be made automatic. STEP is an international standard for geometric and non geometric data transfer between heterogeneous CAD, CAE and CAM systems and it replaces IGES and DXF files. Extracting the necessary information from an exchange file to generate manufacturing parameters becomes an important task. In this paper we present the model of our research effort which is intended to extract the geometric information of rotational parts from STEP file, and utilize this information to recognize the turning features. A generalized Java code has been written to extract the data from STEP file and to recognize the features. The novel approach proposed to extract feature information from STEP files and further integration with STEP-NC file provides as a seamless integration technique of CAD/CAPP/CAM. The approach was tested by several examples for rotational parts.