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BRIDGING DESIGN, MATERIALS, AND PRODUCTION
Copyright © 2004 National Academy of Sciences
All right reserved.
The difficulty of bringing a complex product to market, or a complex weapon system to the warfighter, in a short time and at reasonable cost has long been a concern that will become more acute in the future. The production process has been aided by the introduction, beginning in the mid-1990s, of increasingly sophisticated information technology tools in the United States. The creation and widespread use of new information technology promise to enhance the process of communication between customers, engineers, and manufacturers.
One of the ultimate goals of these improved tools and strengthened communication is to provide methods and processes for collaboration that will link groups involved in the various stages of design and manufacturing. In many cases today, designers are not equipped to take advantage of new materials or modern manufacturing processes. Many manufacturing processes are not structured to handle iterative, or spiral, design improvements, and there are limited avenues for the transmission of information from manufacturing processes to designers and engineers. In short, bridging the gaps across the entire process for product realization could mean reduced cost, shortertime to delivery, and better products.
Over the years, what is called "bridging" in this report has been called concurrent engineering, concurrent design, design for manufacturing and assembly, and many other terms with a similar spirit if not necessarily exactly the same meaning or vision for implementation. "Virtual manufacturing," "spiral development," "simulation-based acquisition," and "modeling and simulation" are terms currently used to describe the potential for various technologies to create these bridges. A well-defined framework of data management, modeling, and simulation tools can help to identify gaps in development or implementation, and can also guide investment decisions in basic research and engineering education. Input from several disciplines-systems engineering, engineering design, materials science, manufacturing science, and life-cycle assessment-is needed for success. Finally, changes to the way customer requirements are specified, especially within defense acquisition processes, are also needed to fully bridge design and manufacturing.
FRAMEWORK FOR VIRTUAL MANUFACTURING
The design and manufacturing enterprise can be interpreted using the flow diagram presented in Figure ES-1. This diagram seeks to capture series and parallel activities at several levels of detail over time during the development of a product. At the lowest level (the bottom of the "V"), individual components are designed and manufactured for integration into subsystems. In an automotive context, components might include brake rotors, suspension parts, or engine control computers. At the next level (the middle of the V), these components are assembled into subsystems-the brake subsystem, the suspension subsystem, or the engine. The subsystems are then integrated into a platform, in this example, an automobile. Finally, at the enterprise level (the tips of the V), such matters as marketing, distribution, and life-cycle management are considered.
Bridging design and manufacturing requires the ability to conceptualize, analyze, and make decisions at all levels of the V in Figure ES-1. Using this framework, knowledge and information from several disciplines can be integrated to make intelligent decisions at all levels. New tools can enable the effective application of this process. As depicted by the color scheme in Figure ES-1, software tools are not available (red) for many of the required product development activities. For other activities, software tools may be emerging (yellow) or common (green) but are not interoperable and so are not used together, or are used inefficiently. When tools are fully interoperable, designers and engineers can use and link various data and models for a given activity as well as across different activities required for product realization. For example, tools that allow data to be easily shared instead of being regenerated or re-entered are more efficient, as are tools that allow information at all levels to be viewed with an appropriate amount of abstraction.
TOOLS FOR VIRTUAL MANUFACTURING
Recommendation 1. Systems Engineering: The Department of Defense should develop tools to facilitate the definition of high-level mission requirements and systems-level decision making. Tools to create, visualize, and analyze design and manufacturing alternatives can facilitate systems-level decision making. A specific opportunity is to develop tools for converting customer needs into engineering specifications, and for decomposing and distributing those specifications to subsystems and components.
The design and manufacturing process leading to product realization is essentially a system of systems. Performance requirements set at the highest level flow down to the other levels in the form of system and interoperability specifications. Conceptual designs are broken down into subsystem and component designs. Decisions are then made about materials, assembly, and manufacturing processes. Information may also flow back up this chain to modify the design.
Such a sequential approach, however, can lead to inefficiencies. Decisions may be made at one level without full consideration of the implications for other levels. For example, parts may be designed that cannot be manufactured or parts can be manufactured that are difficult to assemble. Simple manufacturing processes may be impossible to use because of an arbitrary design specification. A systems engineering approach can avoid these consequences by requiring collaboration at different levels and collective decision making.
Moving from a linear approach to an integrated systems-level approach may require substantial cultural and organizational changes. In order for such an approach to work, all of the participants require access to sufficient and timely information.
Recommendation 2. Engineering Design: The Department of Defense should develop interoperable and composable tools that span multiple technical domains to evaluate and prioritize design alternatives early in the design process.
Improving interoperability, composability, and integration of design and manufacturing software is a complex problem that can be addressed with near-, mid-, and long-term objectives. In the near term, developing translators between existing engineering design environments and simulation tools can solve problems with minimum effort. In the mid term, a common data architecture can improve interoperability among engineering design environments and simulation tools. Key long-term research goals include (1) the development of interoperable modeling and simulation of product performance, manufacturability, and cost; (2) the creation of tools for automated analysis of design alternatives; and (3) the application of iterative optimization using both new and legacy codes.
Almost 70 percent of the cost of a product is set by decisions made early in the engineering design process. If system integrators have the ability to see and work with a large design space, they can better analyze trade-offs between alternatives. Designers need to be able to work within a multidimensional space where design alternatives can be effectively compared. While adequate design tools exist for making decisions within a narrow framework, mature tools do not exist for making decisions over the broad range of design and manufacturing shown in Figure ES-1.
The ability to integrate modeling and simulations across multiple domains is yet to be demonstrated. Domains may include geometric modeling, performance analysis, life-cycle analysis, cost analysis, and manufacturing. If such simulations were able to integrate system behavior and performance in multiple domains, performance, manufacturability, and cost information could be considered and optimized early in the design process. Such integration will require giant leaps in interoperability among various software packages and databases.
Recommendation 3. Materials Science: The Department of Defense should create, manage, and maintain open-source, accessible, and peer-reviewed tools and databases of material properties to be used in product and process design simulations.
Integrated tools and databases for materials design, materials selection, process simulation, and process optimization are key to virtual manufacturing. Data gathered from manufacturing and materials processing using a variety of sensors can validate and improve design, modeling, simulation, and process control.
Effective use of today's materials can be greatly enhanced by using software tools. In particular, databases of accurate and well-characterized material properties would have a significant impact on the quality and speed of product design and manufacturing. Validation by peer review of such databases is essential for their acceptance.
Materials that are currently used in defense systems will continue to be the most important ones used in production in the near term. However, the relationships between structure and properties in even the most common materials are yet to be completely understood, and their potential has not been fully realized. Thus, continued funding of fundamental research aimed at characterizing the relationships between processing, structure, properties, and performance in these materials is warranted. Both experimental investigations and fundamental simulations are necessary to understand these relationships.
The variety of forming processes by which materials are converted into products-casting, forging, stamping, cutting, molding, and welding, for example-can all be simulated by modeling and analysis. However, the fidelity of these analyses depends strongly on the properties of the material in a variety of states and under different external conditions. This dependence makes a strong case for an extended database of materials properties. In addition, even when databases exist, many analysis codes suffer from a lack of interoperability with each other and with specific databases.
Any simulated process is only valid within prescribed boundary conditions. Often, the boundary conditions are not well characterized or are unnecessarily limited, and this limits use of the generated data. Sensors can be deployed in both research and manufacturing environments to improve the fidelity of the simulations of various manufacturing processes. As an example, solidification processing is an area where sensors are used effectively. Because the interfacial heat transfer characteristics cannot be completely predicted, temperature sensors embedded in the mold are used to adjust the simulation parameters. The use of such sensor data in conjunction with modeling can provide control for many other manufacturing processes as well.
Validated data can also be used to develop methods to predict material properties from fundamental physics and to develop constitutive models that predict behavior for a wide range of materials and conditions that are outside measured boundary conditions. Success in this area will greatly enhance the next generation of virtual manufacturing.
Recommendation 4. Manufacturing: The Department of Defense should assess the role and impact of outsourcing on the integration of manufacturing and design functions.
Assessing the impact of outsourcing key activities can help determine how to minimize complexity and maximize coordination in various organizational structures between manufacturing systems. Tools that include efficient algorithms for production scheduling and procedures for flexible factory design can ease the difficulties of outsourcing.
Improvement in the coordination of design and manufacturing involves both technical and organizational actions. Within a single company, coordination between design, materials supply, production scheduling, and process control, for example, can be difficult; outsourcing of tightly coupled design and manufacturing activities adds complexity to an already complex communication process. For example, software tools in use across many organizational boundaries may not communicate without substantial effort.
Creation of new technical knowledge in manufacturing will not be sufficient without accompanying improvements in management methods and organizational arrangements used for outsourcing. These include how to structure cross-functional teams, how to transfer information in a timely manner between team members, and how to identify and resolve conflicts and discrepancies. Implementing the results of research in this area from both business and engineering schools will help improve design-manufacturing coordination. Organizational and managerial structures that facilitate teamwork can make manufacturing efficient and can overcome the tendency toward decentralization that is magnified by outsourcing.
Economic models can estimate the private and public rate of return for investments in virtual design and manufacturing tools and help characterize how incentives and organizational structures affect the adoption of these tools. Economic models of outsourcing choices can also help to assess the strategic impacts on companies, industries, and national defense. The loss of national capability due to outsourcing to offshore companies may become clearer with more appropriate models. Outsourcing of software development, in particular to offshore companies, may represent a substantial barrier to interoperability.
Recommendation 5. Life-Cycle Assessment: The Department of Defense should develop tools and databases that enable life-cycle costs and environmental impact to be quantified and integrated into design and manufacturing processes.
Establishing and maintaining peer-reviewed databases for environmental emissions and impacts of various materials and manufacturing processes will be critical for the government to integrate these factors into acquisition processes. Environmental performance metrics that combine multiple impacts are most useful for design decisions. The development of high-level optimization methods can allow analysis of the trade-offs between cost, performance, schedule, and environmental impact.
In a systems approach to design and manufacturing, the cost of a product over its entire life is considered. Cost can be viewed from several dimensions. First, there is the acquisition cost of a product that includes design, development, and manufacturing. After acquisition, operating, or ownership cost is incurred by operators of the product, which is particularly relevant for defense systems that may last generations. In this case, design decisions can have a profound impact on the adaptability of defense systems to modification or retrofits. Third, there is the environmental impact of manufacturing processes and end-of-life recycling or disposal.
The metrics for quantifying all of these assessments are challenging. Accurate assessment is difficult because gathering the necessary data is expensive and also may be subjective or arbitrary. One reason is that recycling is often done by widely distributed small businesses that operate with a variety of business models, making the economics of the industry opaque.
Different disciplinary areas are directly involved in the design and manufacturing process-systems engineering, engineering design, materials science, manufacturing, and lifecycle assessment. Other supporting infrastructures are involved indirectly and affect all of these specific fields in an overarching way.
Recommendation 6. Engineering Education: The Department of Defense should invest in the education and training of future generations of engineers who will have a thorough understanding of the concepts and tools necessary to bridge design and manufacturing.
Excerpted from RETOOLING MANUFACTURING Copyright © 2004 by National Academy of Sciences. Excerpted by permission.
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1 THE NEED TO BRIDGE DESIGN, MATERIALS, AND PRODUCTION....................8
History and Status....................8
2 FRAMEWORK FOR VIRTUAL DESIGN AND MANUFACTURING....................11
Processes and Tools Common to Many Industries....................12
Product Development, Manufacture, and Life-Cycle Support Activities....................16
Specific Activities in Mechanical Parts Industries....................19
Specific Activities in Electronics Parts Industries....................20
Modeling and Sensing....................21
3 TOOLS FOR VIRTUAL DESIGN AND MANUFACTURING....................23
Tool Evolution and Compatibility....................23
Systems Engineering Tools....................29
Engineering Design Tools....................39
Materials Science Tools....................45
Life-Cycle Assessment Tools....................61
4 ECONOMIC DIMENSION OF BRIDGING DESIGN AND MANUFACTURING....................70
The Cost of Bridging....................71
Identifying the Expected Benefits....................71
Impacts on Productivity Growth....................72
Understanding the Role of Government....................72
5 BARRIERS TO VIRTUAL DESIGN AND MANUFACTURING IN DOD ACQUISITION....................74
Need for Definition and Management of Requirements....................74
Need for Building Linkages Across All Phases ofDoD Acquisition....................77
6 SUMMARY, RECOMMENDATIONS, AND RESEARCH NEEDS....................81
Leveraging Design and Manufacturing in the DoD Acquisition Process....................89
APPENDIXES A Biographical Sketches of Committee Members....................93
B Meeting Agendas....................97
C Current Engineering Design Tools....................99
D Selected Computer-Based Tools Vendors....................104