Analysis and Evaluation for STEP-Based Electro-Mechanical Assemblies: An Integrated Fuzzy AHP Approach

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.

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.

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.

Most CAD tools currently do not have advanced capability built in for directly analyzing the feasibility of product assembly during the design stage. As a result, the feasibility of product assembly has to be analyzed using external assembly analysis tools. To integrate external assembly analysis tools with CAD tools, geometrical data from the CAD models must be extracted from CAD files and imported into the assembly analysis tools. To transfer geometrical data between CAD tools and assembly analysis tools, a neutral file format is needed. STEP (standard for the exchange of product model data) is a neutral file format for convenient and reliable data exchange between different design and manufacturing systems. Therefore, STEP is considered as one of the most popular formats for saving designs. As a result, to evaluate designs, extracting geometrical data from CAD-STEP file is important. Comparing with some other currently available methods, first translating STEP file into XML and then using Java DOM to get geometrical information from XML file is much better. This paper explores the process of extracting geometrical data from a CAD-STEP file for assembly sequence planning. A STEPXML translator, Java-XML parser and DTD (document type definition) generator are used on the JDK 1.4 platform. In this project, DOM (document object model) is applied as the API (Application Programming Interface) for XML.

Various studies have focused on developing an interface system that could integrate the machining process with CNC (Computer Numerical Control) machine tools by producing tool paths using STEP (Standard for the Exchange of Product model data) file as an input function. Studies to recognize features in STEP file by encoding the data of geometric entities of a CAD (Computer-Aided Design) design has been done by many researchers. However, they only focus on Cutter Location (CL) which eventually describes the machining profile in the x and y planes without considering the depth of the machining feature in the z-axis. Identifying and recognizing machining features in the STEP file is important since STEP is a platform for converting industry-standard CAD systems and software data models. The aim of this paper is to identify profiles of geometric machining features for rectangular fillet blind pockets using the Geometric Data Extraction (GDE) approach. Three cases have been carried out namely single rectangular fillet blind pocket, double rectangular fillet blind pocket and triple rectangular fillet blind pocket. The results were verified by manual graph plotting and automatic graph plotting using CPM 3D Plotter.

The additional requirement imposed on any dasiadasianeutral data formatpsilapsila such as STEP (standard for the exchange of product data), has been a Web-enabled data representation. STEP allows dynamic sharing of data between different systems with the standard data accessing interfaces. A method for STEP and XML to be combined in presenting product information was studied. EXPRESS language (i.e. SCHEMA) is used for defining the data structure and DTD is used for XML transactions and presentations. Technologies on integrating STEP with XML have been discussed. A prototype system has been developed making use of STEP and XML as the data modelling and presentation tools.

Implementing ISO standard 10303 application protocol 224 for automated process planning

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.

Automated tools which can understand and interface with CAD (computer-aided design) models are of significant research interest due to the potential for improving efficiency in manufacturing processes. At present, most research into the use of artificial intelligence to interpret three-dimensional data takes input in the form of multiple two-dimensional images of the object or in the form of three-dimensional grids of voxels. The transformation of the input data necessary for these approaches inevitably leads to some loss of information and limitations of resolution. Existing research into the direct analysis of model files in STEP (standard for the exchange of product data) format tends to follow a rules-based approach to analyse models of a certain type, resulting in algorithms without the benefits of flexibility and complex understanding which artificial intelligence can provide. In this paper, a novel recursive encoder network for the automatic analysis of STEP files is presented. The encoder network is a flexible model with the potential for adaptation to a wide range of tasks and finetuning for specific CAD model datasets. Performance is evaluated using a machining feature classification task, with results showing accuracy approaching 100% and training time comparable to that of existing multi-view and voxel-based solutions without the need for a GPU.

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.

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.

Standards are increasingly important for ECAD frameworks. The emerging international standard for the exchange of product model data (CAD data, CAM data,...) is ISO 10303 “Industrial automation systems and integration — Product data representation and exchange”, better known as STEP (STandard for Exchange of Product data). This paper addresses the STEP technology for ECAD databases.

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.

An approach to accessing product data across system and software revisions

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. >