A. de Pennington

Product data models

Product data models can be viewed as a class of semantic data models which take into account the needs of engineering data. In this paper the characteristics for semantic data models defined by Peckham and Maryanski [8] are taken as a starting point. The relevance of these characteristics to product data is shown. The capabilities of a prototype product description system are described in relation to the same characteristics. Additional data modeling characteristics such as parametrization and data sharing, which have been introduced to support engineering design, are then described. These can be viewed as extending beyond the accepted capabilities of semantic data models.

A framework for product data

IT support for engineering involves the integration of existing, evolving and future product data, and software that processes that data. Thus, there is increasing interest in the representation of product data in the computer to support CAE applications. To avoid duplication and inconsistency, and to support the use of new implementation technology as it emerges, conceptual models of product data are required. Such models are independent of the software and hardware environments in which they are implemented. System architectures to support the integration of applications at implementation time are becoming an accepted part of engineering information systems. To use these software support environments effectively, integrated product data is required. It must also be possible to extend the integrated product data in a controlled fashion if it is to evolve to support future engineering applications effectively. A framework that is a part of the product data at the conceptual modeling stage helps to satisfy these requirements. The framework presented is a structure for the information content of product data rather than for the implementation of such data. Product data based on the framework can be successfully implemented in a number of different database forms. This paper describes a framework for electromechanical product data that has been implemented in a structure editor and is being used to support a range of engineering applications. The process of product data integration can be improved by using existing integration strategies together with a framework that provides an overall organization for the data.

Reasoning about machining operations using feature-based models

SUMMARY The success of future automated planning systems greatly depend on further advances in two areas: (a) enhanced product modelling systems capable of answering questions posed during the planning phase; and (b) techniques for representing and manipulating planning knowledge The work reported in this paper, investigates the use of a feature-based approach for modelling engineering parts to support the product data requirements of an intelligent planning system, employing the frame-based and rule-based knowledge representation techniques from artificial intelligence research. The approach has been applied to the domain of rotational parts.

A graph grammar approach to feature representation and transformation

Abstract Feature-based modelling is an approach being studied for the next generation of intelligent CAD environments. In particular, feature mapping, i.e. how to support automatically the different ways specialists view the same object, has been identified as an important element in feature-based design systems. Consequently, feature representation and reasoning tools based on the representation are crucial issues. This paper addresses the problems of representing features in a form more suitable for feature transformation and the related feature reasoning mechanism. Our approach combines methodologies from both design and features and feature recognition. Geometric constraints are used within symbolic definitions of features and also to define their relative positions and orientations. A graph grammar parsing is combined with knowledge-based techniques to derive feature information and propagate constraints. The proposed approach can be used for the transformation of feature information and to facilitat...

A Web-based tool and a heuristic method for cooperation of manufacturing supply chain decisions

Supply chain issues have been given much attention. Various technologies and concepts have been applied to improving and optimizing supply chain performance. However, few methods to explore supply chain inter-relationships, detect process key problems and co-ordinate planning processes in different supply chain partners are available. A Web-based co-ordinated planning process supported by quality function deployment (QFD) approach is proposed in this research. The planning method is focused on integrating planning processes in supply chains by optimizing each planning process and interactively adjusting key parameters in different business processes. The QFD approach is employed to inter-relate different business processes and detect key problems through Internet technique application, so that the global solution can be heuristically improved. The planning method imitates the real-world supply chain planning environment and provides a mechanism for decision-makers to communicate with quantitative information in planning processes through the Web system. An illustrative case study in packaging industry is conducted to describe the planning procedure. The result of the example shows prospect of the method in improving supply chain cooperation. The approach is expected to facilitate supply chain planning and support managers to solve targeted problems more efficiently.

Early alignment of design requirements with stakeholder needs

Abstract Informality of design requirements is a problem, especially in distributed design teams, because it impacts upon the ability of a team to communicate. Since design requirements drive the design process, their miscommunication results in serious problems; for example, new products that do not align with the needs of the range of stakeholders to whom they are targeted. This, in turn, has a detrimental impact on traditional business performance indicators, such as market share, volume of sales, and profit. The research reported in this paper explored the applicability of requirements engineering and management techniques, traditionally used in the development of software-intensive systems, to the development of electromechanical consumer products. The motivational rationale traceability matrix (MoRal™) is introduced as a means to support the initial analysis of stakeholder needs and attributes, and the derivation of corresponding design requirements. The applicability of MoRalTM is demonstrated through application to a power solution case study. In this instance, the MoRalTM proved to be a powerful means of supporting the derivation of design requirements that are aligned with customer and other stakeholder needs, and are traceable to stakeholder intents.

Constructive solid geometry with sculptured primitives using inner and outer sets

A new method for incorporating sculptured surfaces into a Constructive Solid Geometry (CSG) environment is described. As a preliminary, an overview of a general scheme for computations on CSG represented solids is given. The system, known as Inner Set Outer Set (ISOS), involves inner and outer bounding polyhedral approximations to the primitive solids and is detailed in [Beac89]. A method for simultaneous creation of both sculptured primitives and approximating geometry, by sweeping B-spline curves, appears in [Saia88]. This paper is concerned with expanding and adapting these methods to shapes of a less constrained nature, bounded by B-spline surfaces. The task encompasses theoretical groundwork in finding inner-bounding polyhedra and a reformulation of the underlying method.

The Selection of Surfaces in Inspection Planning for Coordinate Measuring Machines

If probe paths for coordinate measuring machines are to be generated automatically then methods must be developed that can determine which surfaces need to be inspected. Evolving computer based systems supporting engineering design and manufacture are adopting the concept of a Product Model as the central source for the data required by the various activities in the design and production cycle. This paper outlines a product model capable of representing data relating to a component’s geometry, dimensions, specification and manufacturing processes. An inspection planning application then uses the product model to determine which surfaces need to be inspected to ensure that the product conforms to the product specification.

Towards the Integration of CAD, CAE and Fast Free Form Fabrication

Engineering and business complexity varies from manufacturing sector to sector to drive a range of integrating technologies. This paper addresses three of these: information exchange standardisation, new developments in the description of geometry related to product functionality, and layer manufacturing for rapid prototyping.

Interactive Design and Manufacture of Sculptured Surfaces Using the B-Spline Approach

A prototype system for design and manufacture using B-spline curves and patches is described. A number of examples illustrate the capabilities of the system. An assessment of the technique is given.