Showing papers on "Design tool published in 2004"

Reliability-based design optimization of aeroelastic structures

Abstract: Aeroelastic phenomena are most often either ignored or roughly approximated when uncertainties are considered in the design optimization process of structures subject to aerodynamic loading, affecting the quality of the optimization results. Therefore, a design methodology is proposed that combines reliability-based design optimization and high-fidelity aeroelastic simulations for the analysis and design of aeroelastic structures. To account for uncertainties in design and operating conditions, a first-order reliability method (FORM) is employed to approximate the system reliability. To limit model uncertainties while accounting for the effects of given uncertainties, a high-fidelity nonlinear aeroelastic simulation method is used. The structure is modelled by a finite element method, and the aerodynamic loads are predicted by a finite volume discretization of a nonlinear Euler flow. The usefulness of the employed reliability analysis in both describing the effects of uncertainties on a particular design and as a design tool in the optimization process is illustrated. Though computationally more expensive than a deterministic optimum, due to the necessity of solving additional optimization problems for reliability analysis within each step of the broader design optimization procedure, a reliability-based optimum is shown to be an improved design. Conventional deterministic aeroelastic tailoring, which exploits the aeroelastic nature of the structure to enhance performance, is shown to often produce designs that are sensitive to variations in system or operational parameters.

Fuzzy multiple objective decision making approach to prioritize design requirements in quality function deployment

Abstract: Quality function deployment (QFD) is a customer-oriented design tool for developing new or improved products to increase customer satisfaction by integrating marketing, design engineering, manufacturing, and other related functions of an organization. QFD focuses on delivering value by taking into account customer needs and then deploying this information throughout the development process. Although QFD aims to maximize customer satisfaction, technology and cost considerations limit the number and the extent of the possible design requirements that can be incorporated into a product. This paper presents a fuzzy multiple objective programming approach that incorporates imprecise and subjective information inherent in the QFD planning process to determine the level of fulfilment of design requirements. Linguistic variables are employed to represent the imprecise design information and the importance degree of each design objective. The fuzzy Delphi method is utilized to achieve the consensus of customers in...

A systematic procedure for the design of piezoelectric inchworm precision positioners

Abstract: Design equations are developed and integrated into a computerized design tool in order to facilitate the creation of inchworm piezoelectric based positioners. Fundamental to the development of the design tool is the piezoelectric actuator and motor frame stiffness interaction and its influence on positioner performance. A generalized motor frame configuration for each of the motor subsystems is presented and used to generate key initial positioner frame geometry. An inchworm precision positioner is implemented based on the generalized motor frame and the computerized design tool and it is shown experimentally and through finite-element analysis that the design approach is effective for precision positioner design. The prototype of the inchworm positioner developed is shown to have a stiffness in the direction of motion of 88 N//spl mu/m, a maximum thrust of 150 N and a traversing speed of up to 20 mm/s.

Product Design Support: Exploring a Design Repository System

Abstract: This paper reports on a knowledge rich design repository system. Current design tools and methodologies are reviewed and used to identify necessary design knowledge to populate a design repository. Building on previous research, an operational design repository is reviewed. The design repository system demonstrated includes a single point of entry application for product information, a relational database for archiving design knowledge and web-based tools. Web services are used to support design knowledge retrieval through search, browse and real-time design tool generation. From the repository interface, design tools such as bills of materials and design structure and function component matrices are generated. The output design tools are tested in real world design applications and validated. The result is a useful tool — applicable to several phases of product design.Copyright © 2004 by ASME

Optimal Synthesis of Compliant Mechanisms Using Subdivision and Commercial FEA

Abstract: The field of distributed-compliance mechanisms has seen significant work in developing suitable topology optimization tools for their design. These optimal design tools have grown out of the techniques of structural optimization. This paper will build on the previous work in topology optimization and compliant mechanism design by proposing an alternative design space parameterization through control points and adding another step to the process, that of subdivision. The control points assist a specific design to be represented as a solid model during the optimization process. The process of subdivision creates an additional number of control points that help smooth the surface (for example a C2 continuous surface depending on the method of subdivision chosen) creating a manufacturable design free of traditional numerical instabilities. Note that these additional control points do not add to the number of design parameters. This alternative parameterization and description as a solid model effectively and completely separates the design variables from the analysis variables during the optimization procedure. The motivation behind this work is to avoid several of the numerical instabilities that occur in topology optimization and to create an automated design tool from task definition to functional prototype created on a CNC or rapid-prototype machine. This paper will describe the complaint mechanism design process including subdivision and will demonstrate the procedure on several common examples.Copyright © 2004 by ASME

gCSP: A Graphical Tool for Designing CSP systems

Abstract: For broad acceptance of an engineering paradigm, a graphical notation and a supporting design tool seem necessary. This paper discusses certain issues of developing a design environment for building systems based on CSP. Some of the issues discussed depend specifically on the underlying theory of CSP, while a number of them are common for any graphical notation and supporting tools, such as provisions for complexity management and design overview.

AUTOMATING A DESIGN REUSE FACILITY WITH CRITICAL PARAMETERS Lessons Learned in Developing the LINK-UP System

Abstract: We propose an interface design process compatible with scenario-based design methods, but specifically intended to facilitate three primary goals: design knowledge reuse, comparison of design products, and long-term research growth within HCI. This effort describes a computer-aided design tool suite, LINK-UP, which supports the design process for specific genre of systems that cross many domains—notification systems. We describe the vision for LINK-UP, contrasting underlying concepts with typical task-based modeling approaches. To achieve its stated goals, the design process is organized and guided by critical parameters, presenting several challenges that we reflect on through the results of a design simulation study. The possibilities envisioned through this approach have important implications for the integration of reusable design knowledge, HCI processes, and design support tools.

Automated PSpice simulation as an effective design tool in teaching power electronics

Abstract: In this paper, PSpice is used to deepen the student understanding of power electronics and to serve as a design tool for power converter circuits. A library that includes automated versions of dc/dc converters and rectifiers is built in PSpice using ideal switches. The automated version permits students to design converter circuits that meet a set of design criteria. The performance of various designs are tested by plotting the current and voltage waveforms using the graphics postprocessor Probe. The library was introduced to students in a power electronics course, and they have been asked to augment its contents through mini-design projects. The response was positive, which will encourage the extension of the approach to other subjects.

Rollabout: a wireless design tool

Abstract: Deployment of wireless LANs includes two main design issues: selection of access point locations and access point frequency assignments. Properly solving these issues normally involves a trial and error process, and can be very time consuming. The Rollabout design tool partially automates this process, making it quicker and more efficient. When pushed around on a rolling cart, the system collects data from access points and automatically creates a coverage map. With Rollabout, data collection is much faster, and a much larger set of data can be captured. Furthermore, the design tool predicts the coverage changes that result when access points are moved to different locations. It also can produce an optimal set of frequency assignments for any set of access point locations and corresponding coverage areas.

Virtual data representation through selective bidirectional translation

Abstract: A computer-aided circuit design application has a virtual node feature and a design tool. The virtual node feature is adapted to access design specification information in a first data format and to represent the accessed design specification information as a virtual data node object within a list of node objects in a second data format. The design tool is operable on the list of node objects and the virtual data node object.

Tools and patterns in designing multi-agent systems with PASSI

Abstract: In the last years the increasing attention on multi-agent systems (MAS) emphasized the need of a quality software engineering approach to their design and realization. In this paper we propose a comprehensive approach for the development of MAS oriented applications that uses a complete design methodology addressing important issues such as ontology representation, agent collaboration and patterns reuse. The PASSI (Process for Agent Societies Specification and Implementation) design methodology is supported by a specific design tool, granting a great number of automatisms during the design, and a pattern repository for the reuse practice; these are determinant in cutting down the time and cost for developing these systems. During the description of PASSI and its supporting tools, we refer to the most diffused standard for agents (FIPA Foundation for Intelligent Physical Agents) and modeling languages (UML and AUML). We will complete our discussion with some examples of the functionalities offered by these tools.

REDTOP-2: Rocket Engine Design Tool Featuring Engine Performance, Weight, Cost, and Reliability

Abstract: The Rocket Engine Design Tool for Optimal Performance-2 (REDTOP-2) is a newly created engineering design tool for use in the conc eptual and preliminary design of space transportation systems utilizing liquid propulsion rocket engines. REDTOP-2, one of many unique engineering tools commercially available from SpaceWorks Engineering, Inc. (SEI), represents a novel entry into the current suite of propulsion modeling tools. REDTOP-2 is capable of analyzing the flowpath characteristics of numerous engine configurations to perform a power balance of the turbomachinery hardware (pumps and turbines) to achieve a user specified main chamber combustion pressure. The engine performance, in terms of thrust and specific impulse (Isp), is then determin ed based on the results of this power balance and the flow conditions (pressure, temperat ure, flowrate, etc.) in the chamber(s) and nozzle(s). Engine weight is assessed at the main co mponent level using a combination of empirical and physics based analysis methods to provide vacuum, ambient, and sea-level thrust-to-weight (T/W) values. A cost model capable of predicting engine development, first unit, and production costs has been incorporated. Additionally, REDTOP-2 features a topdown modeling approach for computing engine safety and reliability metrics. REDTOP-2 is written in the modern, object-oriented C++ programming language and will execute on PC, Mac, and SGI platforms. Execution times are on the order of 30 seconds to 5 minutes, depending on the computing platform, engine configuration and design option selected by the user. User interface options currently include a command-line execution with ASCII file manipulation, filewrappers for use in Phoenix Integ ration’s ModelCenter© environment, and a PC-based graphical user interface (GUI). This paper will describe the REDTOP-2 tool and its capabilities. Sample results obtained from exercising the tool for a number of different existing engine designs will be presented . Results from a multi-variable sensitivity study on a LOX/LH2 fuel-rich, single preburner staged-combustion engine will be highlighted. Two sample applications involving vehi cle designs will be discussed. The first involves probabilistic/uncertainty analysis for an all-rocket vehicle design and the second the rocket main propulsion system analysis of an airbre athing, two-stage RLV concept with first stage tail-rockets and all-rocket second stage prop ulsion. Finally, future directions in the development of REDTOP-2 will be discussed.

Environmental impact analysis for typical office facades

Abstract: The design of a building facade influences internal thermal and lighting conditions and energy use associated with the provision of these conditions. Key decisions about the building facade are usually taken during the concept design stage of a building, while decisions about the method of providing the environmental conditions are often made later in the design process. This dilemma is addressed by the development of a concept design tool that allows the design team to investigate the effect of facade design on the resulting internal environmental conditions, energy use and environmental impact. The concept design tool was developed by performing detailed thermal, lighting and environmental modelling for a number of generic office building facade designs and a range of parameters that affect directly the environmental performance of an office building. The results are presented in a user-friendly interface requiring a minimum number of inputs. Key parameter outputs (such as temperature, lighting levels, ...

Correct-by-construction layout-centric retargeting of large analog designs

Abstract: Aggressive design cycles in the semiconductor industry demand a design-reuse principle for analog circuits. The strong impact of layout intricacies on analog circuit performance necessitates design reuse with special focus on layout aspects. This paper presents a computer-aided design tool and the methodology for a layout-centric reuse of large analog intellectual-property blocks. From an existing layout representation, an analog circuit is retargeted to different processes and performances; the corresponding correct-by-construction layouts are generated automatically and have performances comparable to manually crafted layouts. The tool and the methodology are validated on large analog intellectual-property blocks. While manual re-design and re-layout is known to take weeks to months, our reuse tool-suite achieves comparable performance in hours.

Design, simulation, and stability of a hexapedal running robot

Abstract: The ability of animals to navigate rough terrain is currently unmatched by their man-made counterparts. Recent studies by biologists have begun to demonstrate some of the principles behind their remarkable capabilities. In particular, studies of cockroaches have shown that they use a feed-forward motor actuation pattern and considerable structural compliance to run quickly over very rough terrain. Their sprawled posture and tuned impedance in their musculoskeletal system enable an instantaneous or ‘preflex’ response to disturbances. This allows for rapid response to the large perturbations experienced when interacting with irregular terrain. Consideration of these principles has led to the design of the Sprawl family of robots, which features one active thruster and one entirely passive rotary joint on each leg. Without these spring elements the robots would not be able to run. With them, they can easily overcome hip-height obstacles without any alteration of their open-loop controller. This thesis describes the development, calibration, and analysis of a three-dimensional dynamic simulation of the Sprawl robots. This simulation was developed as a design tool to investigate the effects of parameter variation, and to gain understanding about how to tune the leg configuration and hip impedance which constitute the self-stabilizing posture of the robot. The simulation is used to characterize the sensitivity of the system's performance to changes in the robots' physical parameters. The key parameters that influence speed and stability are identified, and their effects and the nature of their coupling are investigated. While speed is easy to measure, no universal metric for running stability exists. This thesis discusses four distinct steady-state measures of stability that are applicable to a simulated running robot. The effect of modifying the posture of the robot on stability is investigated for each of these measures. As a demonstration of its utility as a design tool, the simulation is used to tune the performance of one of the Sprawl robots. Changing the leg design according to the model's predictions resulted in a two-fold increase of the robot's speed.

Aircraft Optimization for Minimal Environmental Impact

Abstract: The feasibility of integrating environmental considerations into aircraft conceptual design is explored. The approach involves designing aircraft to meet specific noise and emission constraints while minimizing cost. A detailed noise prediction code (NASA Langley Research Center's ANOPP) is coupled with an engine simulator (NASA John H. Glenn Research Center's NEPP) and in-house aircraft design, analysis, and optimization modules. The design tool and a case study involving a 280-passenger airliner are discussed. The study includes operational aspects, such as steeper approaches and takeoff thrust cutback for noise reduction. Low-emissions (CO 2 and NO x ) designs are also evaluated

LPRAM: a novel low-power high-performance RAM design with testability and scalability

Abstract: To date, all of the proposals for low-power designs of RAMs essentially focus on circuit-level solutions. What we propose here is a novel architecture (high) level solution. Our methodology provides a systematic tradeoff between power and area. Also, it allows tradeoff between test time and power consumed in test mode. Significantly, too, the proposed design has the potential to achieve performance improvements while simultaneously reducing power. In this respect, it stands apart from other approaches where power reduction results in speed reduction. The basic approach here divides the RAM into modules, interconnecting these modules in a binary tree where the tree can be reconfigured dynamically during normal operation and during test mode. Furthermore, during test mode, most of the RAM can be switched off, which provides major power reduction, while test-application time is reduced. The aspect ratio of the modules is allowed to vary as a design parameter. The chosen aspect ratio for module impacts power/access time/area tradeoffs. Such novel features make the proposed methodology of potential practical significance. Also, a design tool is developed which inputs various parameters, such as desired power/performance, giving outputs basic design parameters, such as the needed number of modules, area overhead, and resulting test speed-up.

Morphogenic Evolutionary Design: Cellular Automata Representations in Topological Structural Design

Abstract: This paper provides the initial results of a study on the applications of cellular automata representations in evolutionary design of topologies of steel structural systems in tall buildings. In the paper, a brief overview of the state of the art in cellular automata and evolutionary design representations is presented. Next, morphogenic evolutionary design is introduced and illustrated by several types of cellular automata representations. Further, Emergent Designer, a unique evolutionary design tool developed at George Mason University, is briefly described. It is an integrated research and design support tool which applies models of complex adaptive systems to represent engineering systems and analyze design processes. The paper also reports the initial results of several structural design experiments conducted with Emergent Designer. The objective of the experiments was to determine feasibility of various types of cellular automata representations in topological structural optimization. Finally, initial research conclusions and recommendations for the further research are provided.

A Full Parametric Model for Turbomachinery Blade Design and Optimisation

Abstract: This paper presents a full parametric model of a turbomachinery blade. The model forms the geometric backbone of a new aerodynamic design suite, which aims at speeding up the coupled 2D/3D aerodynamic design process. The approach employed here follows the basic design concepts of turbomachinery blades, which are typically defined by a series of cross-sectional aerofoils stacked at their radial location to a three-dimensional blade. Unlike the geometry management in current design systems, the paradigm of a CAD based Master Model has been incorporated in the geometry definition and the corresponding software architecture. Therefore all blade features have been modelled as computational components in the flexible object-oriented software environment. The blade parameterisation enables the 2D aerofoil construction either from the common superposition of the camber line and thickness distribution or the direct control of the suction and pressure side. The sensitivity of the aerofoil aerodynamic performance with respect to a design parameter can be quickly assessed with a fast 2D flow solver. The parameters of the radial stacking line define the axial and tangential shift of each section. The parametric concept facilitates the inclusion of specific shape control techniques such as curvature manipulation and surface smoothing. Furthermore the use of optimisation methods is greatly simplified by the modular program structure, which allows to access single modules of the blade design tool in a batch job. Since the blade design process involves different coordinate systems, unique mapping functions are essential for a consistent update of the blade geometry during a design cycle. The interface to the CAD system is based on the standard data exchange format STEP. The CFD interface makes use of the NetCDF data format for automatic grid generation.© 2004 ASME

Method for the design of laminated composite materials

Abstract: The fundamental premise of designing structures with laminated composite materials is that the materials can be tailored to meet requirements by choosing the materials, thicknesses or thickness fractions, and orientation angles of constituent materials. Minimum weight, dimensional stability, natural frequency, and thermal conductivity are typical goals. This invention is NOT about the analysis of laminated materials and composites, of which there is no short supply. This invention is about the design of laminated materials, which has traditionally been an iterative event between the designer and the analysis tool. These iterations, if they occur at all, are often the most time consuming aspect of design. The fundamental premise of this invention is that tensor invariants of constituent material properties coupled with a tensor description of the specified material requirements can be used together to design laminated materials. The results of this invention can be used as a stand-alone design tool or as a value-added module in finite element codes. Specifically, by specifying material requirements, designers will use the method to select from a catalog of available materials a set that will satisfy their requirements. The designer is aided in the choice of materials, how much of each material to use, the layup angle orientation of the materials, and the sequencing of those materials in the composite laminate.

Sustainable Chemical Processes and Products: New Design Methodology and Design Tools

Abstract: The current chemical industry is not sustainable, which leads to the fact that innovation of chemical processes and products is too often hazardous for society in general and the environment in particular. It really is a challenge to implement sustainability considerations in the design activities of chemical engineers. Therefore, the main question of this thesis is: how can a trained chemical engineer develop a conceptual design of a chemical process or a chemical product in such a way that the final result clearly contributes to sustainable development? This question is answered after a profound discussion about the current chemical engineering practice and its relation to the sustainability debate. This dissertation claims that sustainable development of chemical engineering practices requires a general design methodology accompanied by a set of design tools. Such a combination of methodology and tools does not exist in the chemical engineering field. The author developed a new design methodology and seven new design tools that enable the incorporation of sustainability issues into the design practice of the chemical engineering field. The application and validity of the methodology and its tools are shown in seven, mainly industrial, case studies.

Conflict-based Method for Conceptual Process Synthesis

Abstract: Xiaoning Li Conflict-based Method for Conceptual Process Synthesis Lappeenranta 2004 79 p. Acta Universitatis Lappeenrantaensis 187 Diss. Lappeenranta University of Technology ISBN 951-764-941-X ISSN 1456-4491 The changing business environment demands that chemical industrial processes be designed such that they enable the attainment of multi-objective requirements and the enhancement of innovative design activities. The requirements and key issues for conceptual process synthesis have changed and are no longer those of conventional process design; there is an increased emphasis on innovative research to develop new concepts, novel techniques and processes. A central issue, how to enhance the creativity of the design process, requires further research into methodologies. The thesis presents a conflict-based methodology for conceptual process synthesis. The motivation of the work is to support decision-making in design and synthesis and to enhance the creativity of design activities. It deals with the multi-objective requirements and combinatorially complex nature of process synthesis. The work is carried out based on a new concept and design paradigm adapted from Theory of Inventive Problem Solving methodology (TRIZ). TRIZ is claimed to be a ‘systematic creativity’ framework thanks to its knowledge based and evolutionary-directed nature. The conflict concept, when applied to process synthesis, throws new lights on design problems and activities. The conflict model is proposed as a way of describing design problems and handling design information. The design tasks are represented as groups of conflicts and conflict table is built as the design tool. The general design paradigm is formulated to handle conflicts in both the early and detailed design stages. The methodology developed reflects the conflict nature of process design and synthesis. The method is implemented and verified through case studies of distillation system design, reactor/separator network design and waste minimization. Handling the various levels of conflicts evolve possible design alternatives in a systematic procedure which consists of establishing an efficient and compact solution space for the detailed design stage. The approach also provides the information to bridge the gap between the application of qualitative knowledge in the early stage and quantitative techniques in the detailed design stage. Enhancement of creativity is realized through the better understanding of the design problems gained from the conflict concept and in the improvement in engineering design practice via the systematic nature of the approach.