STEP Technology for ECAD Databases

There is tremendous need in collaborative design today for the integration of heterogeneous CAx systems. This general practice has serious shortcomings like design discontinuity, limited parallelisation, loss of information, and conversion errors. To overcome these shortcomings, macro-parametric approach (MPA), which is a history-based method of parametric CAD model exchange, has been proposed. The macro-parametric approach is a way to achieve compatible CAD model exchange amongst a variety of mutually incompatible CAD systems. CAD models can be exchanged in the form of a macro file that comprises a sequence of modeling commands. A standard macro file that contains a set of event-driven commands can transfer the designer intent such as parameters, features and constraints. Currently, STEP (STandard for the Exchange of Product model data) as an international standard (ISO-10303, Industrial automation systems and integration - Product data representation and exchange) for the computer-interpretable representation and the exchange of product model data is widely used. STEP is becoming the 'lingua franca' in the area of modelling and exchanging product data. One remaining problem of the using STEP as a neutral format is that it does not retain parametric information such as the designer intent but only the pure boundary representation (B-rep) of the CAD model. The B-rep model without parametric information presents difficulties for engineering changes and it may also lead to an unexpected distortion of shape. This research aims to investigate an exchange method that uses STEP/XML (extensible mark-up) technology to express a set of standard modeling commands extracted from CAD models created by Autodesk InventorTM, to enable the same CAD models are readable and shareable with other CAD application systems.

Validation of an information model for inspection with CMM

The standard for the exchange of product model data (STEP) is an effort geared towards facilitating the computer-readable exchange of the total information used to define an industrial product. STEP is being released as a set of inter-related parts. Application protocols, the 200-series parts, describe the use of integrated resources satisfying the scope and information requirements for a specific application context. A proposal exists to develop an application protocol for the casting industry. This proposal is currently in abeyance and the effort required to complete it should be enormous. This paper attempts to make an analysis of the expected effort by studying a casting process. The steps required to develop a prototype information model that will capture all product data about one costing process are attempted. The problems related to product data representation and exchange are introduced with an overview of STEP. The casting industry is briefly addressed. The proposed approach in independent development of an application protocol is thoroughly analyzed, including development of a DBMS using NIAM methodology, an interface language to link DBMS to different computer systems via a neutral file exchange format, and EXPRESS. Problems and contributions of the approach are discussed. >

Insufficient technologies made good integration between the die components in design, process planning, and manufacturing impossible in the past few years. Nowadays, the advanced technologies based on Standard for the Exchange of Product model data are making it possible. This article discusses the three main steps for achieving the complete process planning for prismatic parts of the die components. These three steps are data extraction, feature recognition, and process planning. The proposed computer-aided process planning system works as part of an integrated system to cover the process planning of any prismatic part die component. The system is built using Visual Basic with EWDraw system for visualizing the Standard for the Exchange of Product model data file. The system works successfully and can cover any type of sheet metal die components. The case study discussed in this article is taken from a large design of progressive die.

Implementing ISO standard 10303 application protocol 224 for automated process planning

An approach to accessing product data across system and software revisions

In the current rapidly changing manufacturing environment, most manufacturing companies have realised that the ability to quickly develop a customised product at competitive prices is very crucial for them to survive in the keen competitive global market. Product modelling has been recognised as one of the key factors in determining the success of various product development strategies and for industrial competitiveness now and in the future. Standard for Exchange of Product model data (STEP) is an international standard designed to provide a complete, unambiguous, computer-readable definition of the physical and functional characteristic of a product through its lifecycle. This paper proposes a STEP-compliant product data model to fully support the complete product information representation and management for injection moulding product development. The data model is developed based on the structure of an injection moulding company. The entire data model consists of six data models which are defined to express information from various departments of the company. The data model is described in EXPRESS language, which can be integrated with other STEP-based product data models and databases. Consequently, the proposed system can be further extended for helping other injection moulding manufacturers to improve their product development process. An information sharing prototype system is implemented based on the proposed product data model to demonstrate the feasibility of the approach.

STEP meets PREMO: Product modelling and new presentation techniques

A crucial issue in concurrent engineering (CE) is the information communication between the heterogeneous computer based systems. STEP is an evolving international standard for the representation and exchange of product data in all phases of the product's life- cycle, that offers an efficient mechanism of information communication for CE. Application Protocols (APs) of STEP support the exchange of product data among different application domains such as CAD, CAE, CAPP, CAM. Therefore, in CE, there is a strong demand for in teroperability between different APs through standardized exchange and shanng of data. This article introduces a systematic approach to implementing the interoperation between APs, which addresses the issue at three levels: Application Interpreted Constructs (AICs), Unit of Functionality (UoFs) and Concept. This paper describes the methodology and illustrates an example of interoperation between AP 203 and AP209 of STEP to demonstrate how to implement the interoperation at the above three levels.

For rapid modelling of ship structure and sharing of product data for a computer-integrated manufacturing system in shipbuilding, this research proposes a data exchange method between two-dimensional drawings and three-dimensional finite element models. The report of the research is followed by appropriately planning the structure of the extracted data based on the Standard for the Exchange of Product Model Data. A set of rules for two-dimensional feature recognition is established, and then the method for the extraction of graphic and non-graphic design information from two-dimensional drawings of transverse sections is presented. An algorithm for rapid modelling of the longitudinal hull structure is proposed, based on data extracted from the transverse sections. This algorithm bypasses the geometric modelling stage required in traditional manual modelling, exclusively making use of the extracted information. The proposal also enriches data exchange, greatly reduces human error in modelling and consequently improves the accuracy of the finite element modelling for the shipbuilding industry.

Enriching standards-based digital thread by fusing as-designed and as-inspected data using knowledge graphs

Draft STEP (Standard for the Exchange of Product Model Data) application protocols, developed by the Navy Industry Digital Data Exchange Standards Committee (NIDDESC), have been issued to define the information content of a product model for a ship. The work reported in this paper combines the existing CAD models of the DDG51 Class design with a newly developed non-graphic database so that the overall information content complies with the STEP protocols. This work represents the first-time implementation of the application protocols and is a significant step in the Navy's plan to do the design of variants of the DDG51 Class totally in computer-aided design (CAD). The combined graphic/non-graphic database is referred to as the DDG51 engineering product model. Emphasis has been placed on populating the non-graphic database with the information necessary to perform all required engineering analyses. The basic schema described in this paper may be extended to support other areas of interest, such as logistics support.

Concurrent engineering involves the integration of people, systems and information into a responsive, efficient system. Integration of computerized systems allows additional benefits: automatic knowledge capture during development and lifetime management of a product, and automatic exchange of that knowledge among different computer systems. Critical enablers are product data standards and enterprise integration frameworks. A pioneering assault on the complex technical challenges is associated with the emerging international Standard for the Exchange of Product Model Data (STEP). Surpassing in scope previous standards efforts, the goal is a complete, unambiguous, computer-readable definition of the physical and functional characteristics of a product throughout its life cycle. The use of STEP will lead to higher, integrated levels of automation based upon information standards and frameworks. Concurrent engineering, through information technology and standards, represents the power of a new industrial revolution.

ISO10303 STEP (STandard for the Exchange of Product model data) released a suite of application protocols covering the most important product life-cycle activities. The maturity in the development and usage of these standard models was conducted to the redesign of the classical architecture of STEP application protocols to a more agile architecture in order to better fit the emergent technologies and facilitate the understanding, development, reuse, and implementation of normalized reference product data models. This paper introduces the new modular architecture of ISO10303, comparing it with the classic architecture of STEP. Then, it describes the structure of the new modular AP236, concluding with a proposal for a graphical framework for the design and development of normalized modules and new modular application protocols.

Recently, advanced information technologies have opened new possibilities for collaborative designs. In this paper, a web-enabled collaborative design environment is proposed, where the product data based on STandard for the Exchange of Product model data (STEP) is managed in a hierarchical database and the product metadata is used to efficiently search and utilize information scattered over the network. Several integrity constraints are depicted using EXPRESS to validate the combination of data from different sources. The knowledge represented as metadata and constraints on the interacting features differentiate this environment from previous ones. The collaborative conferencing system is also introduced to communicate and collaborate simultaneously among the related designers. As a result, the proposed environment allows the distributed designers to more efficiently obtain, exchange and communicate the design information throughout the design process.