Janet K. Allen

A Robust Concept Exploration Method for Enhancing Productivity in Concurrent Systems Design

Productivity is of major economic significance in the current competitive global market. Due to growing costs and globalization of the marketplace, improvements in productivity require the creation of a reliable design through concurrent systems analysis in the shortest possible time. This is particularly important for designing complex engineering systems such as aircraft, automobiles and ships. The Robust Concept Exploration Method (RCEM) embodies a systematic approach that can be used to enhance design productivity by both increasing design knowledge in the early stages of designs and maintaining design freedom throughout the design process. Given the overall design requirements and the systems analysis packages, the RCEM is used to evaluate quickly the design alternatives and to develop comprehen sive, robust, flexible, and modifiable top-level specifications. Central to the RCEM is the integration of robust design techniques, Suhs de sign axioms, and the Response Surface Methodology within the framework of a mathematical construct, called the compromise Decision Support Problem, for multi-objective design problems. The high speed civil transport (hsct) aircraft is used as an example to demonstrate our approach.

Selection Without Reflection is a Risky Buisness ...

In engineering, designers are often faced with decisions involving conflicting objectives. Although existing Multi Criteria Decision Making (MCDM) “methods” can aid decisionmakers in satisfying the required trade-offs, a basic understanding of the assumptions and limitations underlying the approaches is required. It is important to note that all of these so called MCDM “methods” have fundamental shortcomings, which render them inappropriate for carte blanche application. Making an educated decision, as to which method to choose for a particular problem, however, is confounded by the fact that over 70 MCDM methods have thus far been proposed within the literature. Although many approaches, aimed at facilitating the selection of the most suitable MCDM approaches for a particular task, have been proposed, these are misleading since they suggest the existence of a “best” method for a particular problem at hand. The very description of the MCDM techniques as methods is a misnomer, as the majority of them constitutes nothing more than attention directing tools and should be treated as such -with caution. Nevertheless, these attention directing tools, when used appropriately in a proper context, may have a significant amount of utility. It is for this reason that we advocate careful reflection (with regard to the problem at hand, the underlying assumptions/limitations of the attention directing tool considered, and interpretation of results) before selection.

ON A DECISION SUPPORT FRAMEWORK FOR DISTRIBUTED COLLABORATIVE DESIGN AND MANUFACTURE

Modern realities have dictated a paradigm shift in design and manufacture practices towards distributed collaborative efforts. Such efforts at globalized synergy, however, invariably result in information intensive knowledge transfers, requiring not only information management but also deliberate structuring of decisions. This is of special concern in product development, where the interfaces between distinct phases of a design process are not well defined and largely misunderstood. The complexity of related design decisions is substantial. Bandwidth of information in knowledge transfers, high fidelity analyses, and ambiguity associated with interactions among distributed stakeholders engaged in shared, concurrent design tasks further complicate the matter. The result is poor communication, problematic changeovers, and hard-to- manufacture designs. Resulting design processes tend to be iterative and not only increase product development costs and extend time-to-market, but also ultimately impede collaboration. The roles of designers as decision-makers have consequently been occluded and there is a need for consistent decision support throughout the design process. In this paper, we present the concept of a Decision Support Framework for Distributed Collaborative Design and Manufacture. The focus is on providing designers with the means to model, structure, negotiate solutions to, and interface multi-attribute decisions, considering tradeoff in the context of risk and uncertainty.

A Service Based Architecture for Information and Asset Utilization in Distributed Product Realization

The rise of the internet and the increasingly symbiotic relationship between designers and computers have both made information increasingly easy to acquire and have changed the way design is carried out. At the same time, the ease with which information can be gathered has created demand for faster, more flexible design processes. Today, geographically distributed designers can take part in a design by breaking the design process down into smaller, independent tasks. In this situation, both computers and fellow designers become the assets that are necessary to carry out the process of product realization. Each asset provides the lead designer with a service that could be based solely on the experience of other designers or on the software tools available for use over the Internet. The heterogeneous nature of these available assets brings into light a need for a systematic means of exchanging design information and knowledge. The question that arises is: “How can these assets be integrated and used in the design process?” In this paper, we present a framework for integrating various activities along the design time line. The framework is based on XML based standards for communication between various software services and achieving interoperability between them. Simple Object Access Protocol (SOAP) is used as an underlying mechanism for transferring messages between different assets. We also discuss the model used to deploy, search for, and manage the available services on the Internet. Lastly, we discuss the management of the information that is generated as a natural byproduct of the process of product realization. We present an example in which the use of the web-based framework and information management model is demonstrated by using them to integrate the distributed services that make up the Technology Identification, Evaluation, and Selection (TIES) method, a conceptual design exploration method that has already been demonstrated in the literature. We close the paper with discussion of what has been shown and look towards the future of this ongoing work, paying particular attention to its use in a future strategic design framework. 1. FRAME OF REFERENCE Today, industrial enterprises are found spread out all over the world. Companies are expanding their base of operations in a search for cheaper labor, materials, or land, or as a way of bringing manufacturing closer to the targeted market. As this trend continues into the foreseeable future, engineers may increasingly find themselves working on the realization of products that could be designed in one location, built in another, marketed to consumers in a third region, and supported or serviced by a group elsewhere. Given this vision of the future, it is not too much of a stretch to also imagine that the design teams in such enterprises might themselves be split up, with members of the teams distributed amongst the company’s many worldwide locations. While some newer technologies such as broadband internet and cellular phones have eased the barrier that distance creates to verbal and written communication between individual co-workers, there is still a great deal of work to be done in facilitating the meaningful sharing of engineering information and in facilitating or approximating the same sort of collaborative environment that exists when designers are working in the same location. * Graduate Research Assistant, AIAA Student Member § Graduate Research Assistant, AIAA Student Member ¶ Associate Professor # Senior Research Scientist, AIAA Senior Member ** Professor and Corresponding Author, AIAA Associate Fellow. Email: farrokh.mistree@me.gatech.edu. Phone: (404) 894-8412

Critical Path Issues in Materials Design

The purpose of this chapter is to review the existing efforts related to materials design. Concurrent design of materials and products is a compelling, transformative technology for 21st-century competitiveness. It also serves as an interdisciplinary platform for instruction of new generations of materials scientists and engineers. Product design and materials development are not mutually exclusive and independent activities but synergistic components of an integrated product, process, and materials design endeavor. This challenge involves a philosophical and cultural shift toward inductive, goal-oriented synthesis of products and their constituent materials and processing paths, and for this, a systems-based strategy is essential. With an emphasis on the limitations of current capabilities and the associated research and development opportunities, the chapter outlines several critical path issues, such as adequate models and experimental data on different length and time scales for a diverse set of functions that material systems must deliver; techniques for characterizing and managing uncertainty in material models applied to processing paths and structure–property relations, as well as resulting design specifications; tools for linking diverse modeling and simulation tools and methods and related data across length and time scales, functional domains, and material classes; and systems design methods and tools that bridge or integrate the design of materials, manufacturing processes, and products/components.

Overview of the Framework for Integrated Design of Materials, Products, and Design Processes

This chapter provides an overview of the overall design framework and the essential constituents of the framework including robust design, complexity management, and a distributed design framework. It presents a discussion of systems-based design of materials as a design process starting from requirements and ending with the design specifications. Most materials design problems of practical interest involve solutions with property/response sets that conflict in terms of their demand upon material structure at various scales. The chapter describes how to manage complexity in multilevel product and material design. The concurrent design of materials and products provides designers with flexibility to achieve design objectives that were not previously accessible. However, the improved flexibility comes at a cost of increased complexity of the design process chains and the materials simulation models used for executing the design process. Efforts to reduce the complexity generally result in increased uncertainty. A systems-based approach is essential for managing both the complexity and the uncertainty in design process chains and simulation models in concurrent material and product design. The complexity of design process chains is reduced by selectively ignoring interactions between models and between decisions. The chapter also presents two material design examples to demonstrate some of the principles of systems-based robust materials design.

Integrated Material, Product, and Process Design—A New Frontier in Engineering Systems Design

This chapter focuses on various aspects of systems-based concurrent design of materials and products. Design has been defined by the US National Science Foundation (NSF) as a process by which products, processes, and systems are created to perform desired functions through specification. The fundamental objective in a design process is to transform requirements—generally termed “functions,” which embody the expectations of the purposes of the resulting artifact, into design descriptions. The chapter describes the systems-based multilevel design that involves accounting for all aspects of systems from lower length and time scales to higher scales, addressing the multiscale nature of physical structure and behavior. The design process is multilevel in the sense that decisions must be made with respect to structure at each level of material and product hierarchies. Multiple levels of models must be integrated with design decisions in concurrent materials/product design. The design process is multiscale in the sense that multiple length and time scales of material structure and responses are addressed by different models. Multilevel design seeks to make risk-informed design decisions at all scales. Design has traditionally involved selecting a suitable material for a given application. The key element in tailoring these materials is a quantitative understanding of the relation of process route to microstructure, structure to properties, and properties to performance.

Extending Reusable Decision -Centric Templates to Facilitate Collaboration Using Game Theory

Modular, executable, decision -centric templates have been used as a means to model design processes computationally. The use of decision templates has been limited so far to decision making by a single stakeholder . Templ ates for multiple stakeholders, making concurrent decisions regarding the design of a product have not been developed . In this paper, we extend the current template -based approach using Game -Based Design , which is a method incorporating game theoretic prot ocols in engineering design and has been proposed as a means to solve design decision problems for multiple stakeholders. The interaction s bet ween multiple decision makers are modeled using cooperative, non -cooperative, and leader follower protocols . The p roposed approach facilitates collaboration between two stakeholders by organizing design process information u sing decision -centric templates . The proposed approach facilitates computational modeling of designer interactions in a distributed environment by capturing the dynamics of collaborative decision making. It is demonstrated with respect to facilitating the design and prototype manufacture of a separation channel for a microscale gas chromatography system.

Distributed Collaborative Design Frameworks

This chapter provides an overview of the requirements for a distributed design framework for integrated materials and product design. These requirements are addressed in an eXtensible Distributed Product Realization (X-DPR) framework. The X-DPR framework is designed with peer-to-peer communication between agents, where each agent is an independent entity communicating with other agents. It is an open system in which different modules can be easily integrated into the system for enhancing the functionality of the overall system. The elements of the X-DPR framework include data repository, process diagram tool, dynamic UI generation, interface mapping tool, messaging and agent description, publishing a service, asset search service. The chapter reviews the capabilities of existing distributed design frameworks. The approaches for distributed collaborative design discussed are—web-based systems, agent-based systems, distributed object-based modeling and evaluation (DOME) framework, NetBuilder, Web-DPR, and federated intelligent product environment (Fiper). The chapter also provides an illustrative design scenario of linear cellular alloy (LCA) design. Seven distributed software applications are involved in this LCA example; these applications are deployed as agents in the overall robust design process.

Robust Design of Materials—Design Under Uncertainty

This chapter discusses the fundamentals of robust design and uncertainty management in simulation-based design. In engineering design, the concept of robustness is used to mitigate loss of functionality or performance due to reliance on information that is uncertain or difficult to model or compute. Management of uncertainty is crucial in materials design. The degree of uncertainty is often quite substantial in experiments, processing methods, material structure, and model parameters that support concurrent design of materials and products/systems. The chapter defines different characteristic types of uncertainty associated with material design. Several examples of sources of uncertainty are also illustrated. Further, the requirements for new approaches for the management of uncertainty in materials design are addressed. The chapter discusses the Taguchis robust design approach and also describes the robust concept exploration method (RCEM), which is an extension to Taguchis approach. These existing robust design approaches are evaluated against the challenges in materials design to identify the requirements for robust design methods in multilevel design.