Showing papers on "Conceptual design published in 1997"

Computational Design of Hierarchically Structured Materials

Abstract: A systems approach that integrates processing, structure, property, and performance relations has been used in the conceptual design of multilevel-structured materials. For high-performance alloy steels, numerical implementation of materials science principles provides a hierarchy of computational models defining subsystem design parameters that are integrated, through computational thermodynamics, in the comprehensive design of materials as interactive systems. Designed properties combine strength, toughness, and resistance to impurity embrittlement. The methods have also been applied to nonferrous metals, ceramics, and polymers.

DESIRE: Modelling Multi-Agent Systems in a Compositional Formal Framework

Abstract: This paper discusses an example of the application of a high-level modelling framework which supports both the specification and implementation of a system's conceptual design. This framework, DESIRE (framework for DEsign and Specification of Interacting REasoning components), explicitly models the knowledge, interaction, and coordination of complex tasks and reasoning capabilities in agent systems. For the application domain addressed in this paper, an operational multi-agent system which manages an electricity transportation network for a Spanish electricity utility, a comprehensible specification is presented.

Design for multimedia learning

Abstract: Introduction. LEARNING THROUGH INTERACTIVE MEDIA. 1. The Multimedia Learning Revolution. 2. Resources and Tools for Learning. 3. Simulation and Vicarious Experience. 4. Structured Learning. CONCEPTUAL DESIGN: 5. Strategic Approaches to Educational Multimedia Design. 6. Context and Multimedia Design. 7. Design Action Potential. PRESENTATION DESIGN: 9. The Multimedia Toolset. 10. Text and Graphics. 11. Animation. 12. Sound.

Functional reasoning in design

Abstract: A product design process begins with functional or conceptual design, followed by basic design and detailed design. Among these, functional design plays the central role in ensuring design quality and product innovativeness. Because function is the most crucial concept in designing better and more innovative products, functional reasoning technology is indispensable to the development of future advanced CAD technology. This survey shows how functional reasoning has successfully established the representation of function on computers and outlines directions for further research.

Design for multimedia learning

Abstract: Introduction. LEARNING THROUGH INTERACTIVE MEDIA. 1. The Multimedia Learning Revolution. 2. Resources and Tools for Learning. 3. Simulation and Vicarious Experience. 4. Structured Learning. CONCEPTUAL DESIGN: 5. Strategic Approaches to Educational Multimedia Design. 6. Context and Multimedia Design. 7. Design Action Potential. PRESENTATION DESIGN: 9. The Multimedia Toolset. 10. Text and Graphics. 11. Animation. 12. Sound.

Creation of concept shape designs via a virtual reality interface

Abstract: This paper describes an approach for creating concept shape designs in a virtual reality environment— covirds (COnceptual VIRtual Design System). Concept design refers to the ab initio design of a product or part. In concept design, the product details such as shape features and exact dimensions are not rigidly defined and the designer has some freedom in determining the shape and dimensions of the product. Current cad require the designer to specify shape and dimensions to create cad models of products even though these are probably not necessary at the concept development stage. covirds overcomes these drawbacks by providing a bi-modal voice and hand-tracking based user interface to the VR-based cad modeling environment. This interface allows rapid concept design creation without requiring time consuming shape description and the tedious specifications of exact dimensions.

(International Journal of Production Research, 35(4):995-1010)A Fuzzy Outranking Method for Conceptual Design Evaluation

Abstract: The task of design evaluation in conceptual design is important, since a poor selection of design concept can rarely be compensated at later design stages. At that stage, it is difficult to determine the 'best' design alternatives, because information collected is too subjective or too incomplete to make a judgment. In this paper, the imprecise preference structure of various alternatives is modelled with the fuzzy preference relation. Depending on the degree of completeness of design information, three preference modes based on the outranking approach are developed to discriminate the nondominance set from a set of alternatives for further development. The alternatives are removed from further consideration only if there is sufficient evidence to believe that they are outranked by other alternatives. A valve selection problem is used to illustrate the concept. The developed approach is more applicable in the imprecise and uncertain design environment.

A fuzzy outranking method for conceptual design evaluation

Abstract: The task of design evaluation in conceptual design is important, since a poor selection of design concept can rarely be compensated at later design stages. At that stage, it is difficult to determine the 'best' design alternatives, because information collected is too subjective or too incomplete to make a judgment. In this paper, the imprecise preference structure of various alternatives is modelled with the fuzzy preference relation. Depending on the degree of completeness of design information, three preference modes based on the outranking approach are developed to discriminate the nondominance set from a set of alternatives for further development. The alternatives are removed from further consideration only if there is sufficient evidence to believe that they are outranked by other alternatives. A valve selection problem is used to illustrate the concept. The developed approach is more applicable in the imprecise and uncertain design environment.

On Robust Design in the Conceptual Design Phase: A Qualitative Approach

Abstract: SUMMARY One of the most tangible contributions to quality engineering over the last 15 years is the concept of robust design and its concrete realization by means of designed experiments. However, robust design as promoted by the Taguchi method clashes with design theory as it puts emphasis on parameter design as the most important means of robustifying technical systems. It is argued in this article that the design phases that precede parameter design ∥i.e. system design) actually determine the attainable level of product robustness in the parameter design stage. It is shown how qualitative methods in the form of design principles can be utilized in early design phases to support the process of robust design.

Integrating design into the sophomore and junior level mechanics courses

Abstract: Engineering schools across the country are developing ways of integrating design into their curriculum, and a question that often arises is how to best integrate design into the sophomore and junior level courses. Freshman design projects or mechanical dissection courses are designed to give the students hands-on experience in conceptual design and construction, with little if any of the mathematical modeling normally used in engineering design. The capstone senior design project is a true engineering design experience, where students draw from their background to conceptualize, analyze, model, refine, and optimize a product to meet design, manufacturing, and life cycle cost requirements. The sophomore and junior level courses should assist students in making the transition from the “seat-of-the-pants” freshman design approach to the engineering design approach required for the capstone experience and engineering practice. This paper summarizes a three year effort at integrating design into the Mechanics of Materials course, but the principal conclusions drawn would apply to most sophomore and junior engineering science courses.

Integration of Cost Modeling and Business Simulation into Conceptual Launch Vehicle Design

Abstract: NOMENCLATURE This paper reports on research that integrates cost modeling and business simulation into conceptual design environments for advanced launch vehicle programs. A new design-oriented computer tool has been developed and used that is capable of using priceelastic market estimates, price optimization, vehicle characteristics, and historical operations data to predict key business indicators such as return on investment (ROI), internal rate of return (IRR), maximum exposure, and break-even point (BEP). This paper includes a brief introduction to this tool called Cost And Business Analysis Module (CABAM). In addition, this paper reports on the results of work to integrate the cost analyst, via CABAM, into the advanced conceptual design process (i.e. performance, propulsion, aerodynamics, weights, internal layout, aeroheating, etc.). Using industry standard tools and design practices within a controlled university environment, three sample launch vehicle concepts were designed with varying levels of participation from the cost analyst. Successes and difficulties in integration of CABAM are documented. Then, the resulting economic indicators are presented and interpreted for each of the three example conceptual designs to illustrate the type and range of data available. These example results illustrate the potential cost savings and increased profit generation possible when a 'design-for-business' philosophy is used.

Conceptual design, manufacturability evaluation and preliminary process planning using function-form relationships in stamped metal parts

Abstract: A large number of design decisions are made during the conceptual design of a part. However, there are few representation and reasoning tools for decision support during conceptual design. The conceptual design stage is characterized by a lack of complete geometric information. Existing geometric modelers require complete geometric information, while a functional reasoning methodology using a verb, noun > representation is typically too terse. In this paper, we present a new representation called sketching abstraction for conceptual design, using the function-form relations in a design. The functionally critical part of the geometry is presented using a set of functional features, while the rest of the geometry is abstracted as a set of linkages. Part functionality is correlated with the sketching abstraction using data structures called function-form matrices. The sketching abstraction is annotated using a set of primitives, and a set of grammar rules are used to extract canonical relationships between the functional features. The sketching abstraction can be used for extracting designs that are geometrically dissimilar but functionally similar, thus providing the designer with ideas for design alternatives. The sketching abstraction can also be used to carry out domain-dependent manufacturability evaluation checks. A further use of sketching abstractions is to initiate the development of a process plan for manufacturing. Sketching abstractions are related to the solid model of a part. Thus, this representation provides a link between pure functional and pure geometric representations. The domain of application is stamped metal parts. We present the part functionality and the features used in this domain. We also illustrate the use of sketching abstractions for conceptual design, manufacturability evaluation and preliminary process planning.

SCCREAM (Simulated Combined-Cycle Rocket Engine Analysis Module): A Conceptual RBCC Engine Design Tool

Abstract: Rocket-based combined-cycle engines are currently under consideration for use on future, reusable launch vehicles. By combining traditional rocket and airbreathing operating modes into a single engine, multi-mode RBCC engines offer a number of advantages for launch vehicle designers including higher trajectory averaged L^, than pure rockets and higher installed thrust-to-weight ratios than pure airbreathers. This paper presents a new computer tool capable of predicting RBCC engine performance (thrust and 1^) over a wide range of flight conditions and engine operating modes. The tool is called SCCREAM — Simulated Combined-Cycle Rocket Engine Analysis Module. SCCREAM is an object-oriented workstation-level code written in C++. It uses quasi1D flow analysis, component and combustion efficiencies, and an inlet pressure recovery schedule as simplifying assumptions. SCCREAM was created for the conceptual launch vehicle design environment and is capable of quickly generating large tables of engine performance data for use in trajectory optimization. An overview of SCCREAM and the program logic is presented. Results from SCCREAM are favorably compared to historical RBCC engine performance data and to data generated by other engine design tools.

Decision support for conceptual bridge design

Abstract: A knowledge based, decision support tool for the conceptual design of bridges is described. The system incorporates a restructured version of a knowledge base (KB) for conceptual bridge design. The restructuring results in a KB which can be readily altered and extended by system users who are not expert knowledge engineers. This is achieved by using a novel form of KB in which the knowledge is fragmented into separate concepts associated with design solutions. The system also includes a new style of user interface which provides a critiquing style of interaction with the KB only interacting with the user when it detects a possible error or a more suitable design solution. The new system has been developed using object oriented programming techniques which result in a structured and robust style of KB.

Design of experiments for fitting subsystem metamodels

Abstract: For complex systems, traditional methods of experiencebased design are ineffective: the design task must be supported by simulations. Conceptual design and system-level detailed design based on numerical simulation models is limited because of the difficulty in integrating disparate subsystem models to predict overall system behavior. A metamodel-based integration strategy allows simulation results from multiple submodels to be combined into a system-level simulation. The development of a metamodel-based integration strategy for system-level design depends on effective experiment design strategies for fitting and updating subsystem metamodels.

Intelligent reasoning assistant for incorporating manufacturability issues into the design process

Abstract: This paper describes an integrated Intelligent Reasoning Assistant (IRA) as an approach to incorporate manufacturability issues into the design process. By using a series of pre-established geometric features available from a CAD system and manufacturing knowledge captured from experienced design and manufacturing personnel, the proposed model is used to recommend feasible manufacturing process sequences and design changes that enhance design manufacturability early in the conceptual design stage. The used Design For Manufacturing (DFM) approach assumes that incorporating manufacturing issues into the design process is not a serial decision method, rather, it is a process with multiple parallel interactions from origination of a conceptual design to direct linkage with manufacturing parameters. Although the emphasis of this research has been focused on part designs which are metal machining intensive, it is believed that the described approach can be generalized to other manufacturing environments.

Propellant management device conceptual design and analysis - Galleries

Abstract: While surface tension devices have been used in liquid propellant tanks for over thirty years, the conceptual design process and the analytical methods used to verify performance have been closely held by propellant management device (PMD) designers. This paper is the fourth in a series which will address the process and the techniques developed and used by PMD Technology to design and verify a PMD component - the gallery. 1,2,3 All areas of concern inherent in gallery design and implementation will be addressed - starting from the dictating requirements, proceeding into the design configuration choice, and ending with required performance analysis. The result is a cohesive process by which one may design and verify the performance of the gallery PMD component.

Estimating Resource Requirements at Conceptual Design Stage Using Neural Networks

Abstract: Construction conceptual estimating models provide frameworks for evaluating different alternatives at the conceptual design stage. Estimations are prepared in practice primarily based on analogy with previous similar cases. A back-propagation neural-network model was developed in this study to estimate the construction resource requirements at the conceptual design stage. The developed model was applied on the construction of concrete silo walls built by using the slipform system. A set of 23 input attributes that mostly pertain to the determination of the resource requirements were identified. These input attributes include the bulk density of the stored materials, the wall-to-floor area of the silo complex, the number of lifting jacks of the slipform, and the number of stages through which the silo complex is constructed. The developed model was used to calculate the requirements from nine construction resource types. Outputs of the developed neural-network model were compared with estimations obtained from using multiple regression models. The results indicated that back-propagation neural-network models can be used satisfactorily to estimate the construction resource requirements at the conceptual design stage.

Conceptual Design Reconsidered: The Case of the Internet Session Directory Tool

Abstract: We report a case study in which conceptual design was applied to create a user interface of an innovative software tool. The Session Directory Tool (sdr) allows users to set up and participate in real-time interactive multimedia events on the Internet. To make this functionality available to users who are not familiar with the underlying network technology and videoconferencing, we identified a metaphor which could be extended into a design model (Electronic TV Listings Guide), and communicated this model through linguistic and structural features of the user interface. Evaluation results indicate that this effort was largely successful: new users handled sdr competently after a short training session and 5 days’ practise, and articulated their knowledge of the tool in terms related to the design model. The case study demonstrates the potential of conceptual design, integrated with tangible HCI design techniques, for developing user interfaces to innovative technology.

Mechanism concept retrieval using configuration space

Abstract: When designing mechanisms, making use of examples in past designs and handbooks should lead to cost reduction by promoting the sharing of parts and subassemblies among the products as well as reduction of time and effort. At present, however, the process of surveying design examples is left almost entirely to human designers and little computerised aid has been developed. We propose a computerised method of retrieving mechanism concepts from a library by specifying a required behaviour using qualitative configuration space as a retrieval index. First, mechanism concepts and their kinematics characteristics are described and stored in a computerised library using qualitative configuration spaces accompanined by additional information such as motion type and motion transmission direction. To retrieve mechanism concepts which realise specific kinematic behaviour, designers specify the required behaviour as timing charts of given input and intended output motions. Motion types, motion transmission direction, and motion speed dependence of the input and output motions can also be specified. Computer programs translate the required timing charts into required locus patterns in motion parameter space, and then available mechanism concepts to realise the behaviour are retrieved based on pattern matching between the qualitative configuration spaces and the locus patterns. The method is implemented as an experimental computer program written in Prolog and applied to simple mechanism design problems as examples to confirm the effectiveness of the approach.

Assembly oriented design: a new approach to designing assemblies

Abstract: This paper presents a new approach to conceptualizing the design of complex assemblies. In the past designing individual parts and assembly planning have been treated as two separate activities. This paper presents an integrated design approach where assembly planning becomes an essential part of the conceptual design activity. A concept called datum flow chain (DFC) is introduced to represent the underlying logic of an assembly at an abstract level. The paper introduces an approach that integrates a way to relate the DFC to the key characteristics (KCs) of a product, identify the most promising assembly sequences, and the use of DFC and three-dimensional tolerance analysis to assess the most promising sequences and part features. A case study performed on assembly of a family of aircraft skin panels is used to illustrate the method.

Conceptual design of isolation systems for bridge structures

Abstract: In the first part of this paper the objectives of an isolation system for a bridge structure are discussed, in relation to modelling options and modification of the traditional capacity design prin...

Evaluation of Failure Diagnosis in Conceptual Design of Mechanical Systems

Abstract: This paper discuses a methodology for improving quality and reducing life cycle costs of mechanical systems. The principal concept is that a system can be designed, in the conceptual stages, to be easier to diagnose for failures. To perform this, functional decomposition and form-to-function mapping are utilized to demonstrate the relation of design to diagnosis and for diagnosis itself. Four diagnosability metrics are developed and four hypothetical conceptual designs are evaluated for diagnosability and compared. An example is presented wherein three conceptual designs for a toolhead positioning system are evaluated for diagnosability at two levels of abstraction and the results compared. The area of design for diagnosis offers promise in improving system quality and reducing life cycle cost; research is continuing to refine and integrate the procedures with other aspects of the concurrent engineering design process.

Reducing Design Cycle Time and Cost Through Process Resequencing

Abstract: In today''s competitive environment, companies are under enormous pressure to reduce the time and cost of their design cycle. A software tool, the Design Manager''s Aid for Intelligent Decomposition (DeMAID), has been developed to aid the design manager in reducing the cost and time of the design cycle through understanding the sequence of design processes and the effects of iterative subcycles often found in complex design projects. Once these are understood, the design manager can make decisions that take advantage of decomposition, concurrent engineering, and parallel processing techniques. DeMAID is a knowledge-based software tool for minimizing the feedback couplings; sequencing the design processes; grouping processes into iterative subcycles; decomposing these subcycles into a hierarchical, multilevel structure for a design cycle; and displaying the sequence of processes in a design structure matrix format. Once the iterative subcycles have been determined, the real benefits of producing the best design in the least time and at a minimum cost are obtained from sequencing the processes within these subcycles. A genetic algorithm has been added to rapidly examine many possible sequence combinations. A sample conceptual design project shows how DeMAID can be applied to reduce the time and cost of the design cycle.