Concurrent Engineering

The thesis of this paper is on the development of an integrated design system called Design Function Deployment (DFD), which pro vides a platform for the adoption of the concurrent engineering approach to product development The paper commences with discussions on the objectives and rationale for the development of the design system The contributing factors to its development are also elucidated DFD is then examined in terms of what it is, its design model, and how concurrent engineering is implemented within it The paper concludes with a con cise discussion of some of the key concurrent design methods constituted within it and work done to date toward the software Implementation of DFD

This paper concentrates on two types of material-related reasoning that occur in engineering design selection and substitution Selec tion is based on criteria set out by the designer and is often associated with the process of designing new artifacts from scratch Substitution, on the other hand, is done when new designs are created by adapting and reusing parts of previous designs This involves reevaluating the reasons for a particular material that was used in the base design, and determining whether the same, or new criteria are relevant in the target design Once the new criteria are established, appropriate materials are selected and substituted The substitution step, hence, subsumes the selection task. We present a material selection/substitution system that is used as part of a larger case-based design environment [9]. The material selection system helps the designer adapt previous designs by suggesting material substitutions that better suit the target application The system is in tended to provide support, from the conceptual to the detailed stages of design, and reason about material properties expressed in both numeri cal and qualitative terms The system relies on the material selection charts developed by Prof Ashby of Cambridge University. To enable qualita tive reasoning about the charts, we have developed an encoding based on fuzzy set theory This allows access of materials using specifications expressed in terms of fuzzy orders of magnitude.

Design and operation of process plants are now dominated by constraints imposed by safety, environmental impact, waste minimiza tion, cost effectiveness, controllability, and operability over the complete product and process life cycle including market analysis, conceptual and detailed design through to commissioning, operation, and disposal of products and decommissioning of the plant This means it inevitably in volves a large number of activities carried out by teams of engineers which draw on a variety of technologies that rely on diverse types of informa tion having complex data structures and relationships which must be shared by team members and integrated through computer based software packages Conflicting goals, uncertainty, and multiple solutions are crucial elements of these activities which are essentially about decision mak ing This paper describes the architectural and functional characteristics of a computer integrated concurrent engineering environment for life cy cle chemical manufacturing which allows project teams to work over a heterogeneous computer network Emphasis is placed on the key imple mentation issues with specific attention being paid to STEP-based chemical process data modelling, information sharing and communication, and distributed agent cooperation. The benefits this approach can bring are illustrated by considering the revamp design of a refinery fluid cata lytic cracking process, particularly in respect to the way the environment supports the project team

Engineering design is a highly integrated and integrating process. This two-part paper describes an integrated computer-based plat form for the development from first principles of design solutions to an appropriately defined need, and the choice and quantification of the best forms of embodiment

Engineering design is a highly integrated and integrating process This two-part paper describes an integrated computer-based plat form for the development from first principles of design solutions to appropriately defined need, and the choice and quantification of the best forms of embodiment

In this paper, a new methodology is presented to solve the tolerance allocation-process selection problem simultaneously The prob lem is modeled using discrete and continuous variables and is transformed into a model with only continuous variables by defining an efficient tolerance-cost curve for each component Since the efficient tolerance-cost curve is neither convex nor concave, nonlinear programming method ologies cannot be directly applied The tolerance-cost curve is piecewise linearly approximated and an efficient methodology is developed to solve the problem The method starts with a solution which minimizes the objective function value but is not feasible The infeasibility is iteratively reduced in a way that the increase in the objective function value is minimal Computational analysis indicates that the method is very robust and requires negligible CPU time

This paper presents a data management model to support collaborative design environments Specifically, the proposed model describes a multidisciplinary project in terms of the independent evolution of designs from the participating disciplines The model monitors inde pendent design activities by systematically tracking component descriptions in the individual disciplines Projects are coordinated through asyn chronous communication of design changes This paper discusses two salient features of the given model First, we specify a three-layered closely coupled framework of versions, assemblies, and configurations In this framework, versions maintain evolving descriptions of primitive en tities within a single discipline Assemblies integrate component instances to describe more complex entities, as well as designs within single dis ciplines Configurations provide a framework to describe an overall project design that is composed of designs from multiple disciplines Secondly, we introduce equivalent operations as single data operations that summarize the effect of a sequence of changes on an instance description, and apply this concept to detect, store, and manage changes among versions of a primitive entity The close coupling of the version, assembly, and configuration levels enables changes at various assembly and configuration levels to be characterized by recursively combining changes computed at the version level We use a simple example of a multidisciplinary facility design project to demonstrate the change manage ment capabilities of the model This example has been tested on a prototype implementation in the AUTOCAD environment using AUTOLISP as the programming interface