Charters of Freedom Encasements in a Design Repository: a Case Study

We report on a case study representing, in an evolving design repository, the design essence of new encasements for the United States Charters of Freedom (CoF)—namely the Constitution, the Declaration of Independence and the Bill of Rights. Specifically redesigned for the purpose of housing and preserving our national documents, the nine encasements each consist of three principal systems—a sealing system, a placement system and a safeguarding system. The encasements were needed to replace the ones manufactured in the early 1950s, because of glass deterioration; these newer encasements are designed to last 100 years. To populate the design repository, we represent engineering geometry, function and associated behavior. We model geometry with digital photographs and Virtual Reality Markup Language (VRML) models of actual Computer-Aided Design (CAD) drawings, and represent function with linked textual descriptions. Design rationale is represented explicitly. Through an evolving user interface, this representation serves to capture the more than 50 parts and systems of the encasements in such a way that the information relating to form, function, behavior and rationale is accessible and browsable to interested parties via the Internet. We conclude that such a representation, or ones similar to it, can provide the basis for a generic design repository, in which specific information—including design rationale—can be readily accessed by interested parties. INTRODUCTION Within the last decade, collaborative engineering (CoE) has become an established methodology for developing products and prototypes [1,2]. In general, design and manufacturing personnel have increased their CoE activities as technology has allowed them to do so. A prime example of this is the recent proliferation of Internet-Aided Design (IAD), where design and manufacturing personnel use the World Wide Web (WWW) for providing information services on the Internet [3-5]. In addition to sharing information, there is a need for, and an increased focus on, representing product knowledge in a way that facilitates storage, retrieval and reuse. This is a formidable engineering problem with over 20 billion CAD models in use [6]. In addition to providing an extensive database to improve the design process, it is also important to provide one in an easily accessible way. The Internet provides a widely accessible and usable platform for conveying information over long distances and to many people at the same time. Internet-related technologies that are beginning to address the accessibility issue include digital libraries [7,8], active catalogues [9], extended databases [10] and design repositories [11,12]. The most recent of these technologies is design repositories (DRs). DRs have extended the capabilities of traditional databases by being more robust in capturing function, behavior and models. In addition, DRs generally accept more heterogeneous information and incorporate more explicit representations than databases [12]. The National Institute of Standards and Technology (NIST) design repository, started in 1996, is a database that supports representing, capturing, sharing and reusing design knowledge. The NIST DR can be used to store much of the data created from a generic design and its associated processes so that the information can be shared with future designers and planners. This paper describes a case study using the NIST design repository to capture the design and reasoning behind the development of the Charters of Freedom Re-encasements (CoFR). The subject of the paper is a case study in product knowledge modeling and representation, as opposed to a paper about the design repository project that uses the encasements as an example. Thus, the focus is in the information modeled, and not the implementation of the Design Repository system. Szykman et al [12, 13] provide more information about the implementation and technical detail about the design repository. After briefly describing the need for a new encasement design, and the associated design and manufacture of them, we present how we populated the NIST DR with knowledge about the CoF encasements. We conclude with our assessment of the benefits of, and the bottlenecks to, the representation of CoFR in the DR.