Kristin Wood | Singapore University of Technology and Design (SUTD) (original) (raw)

Papers by Kristin Wood

Design fixation is a phenomenon that can negatively impact design outcomes, especially when it oc... more Design fixation is a phenomenon that can negatively impact design outcomes, especially when it occurs during the ideation stage of a design process. This study expands our understanding of design fixation by presenting a review of approaches that report its reduction or elimination, as well as metrics employed to understand and account for design fixation. The study then explores the relevant ideation area of Design-by-Analogy (DbA), with a fixation experiment with 73 knowledge-domain experts to overcome design fixation. The study provides a design fixation framework and constitutes a genuine contribution to effectively identify design fixation mitigating approaches in a wide range of design problems, and provides concrete evidence of cognitive mechanisms to overcome fixation.

Design-by-Analogy (DbA) is recognized for its potential for fostering innovation. Previous work p... more Design-by-Analogy (DbA) is recognized for its potential for fostering innovation. Previous work provides insights into how analogies assist in solving problems in engineering design and architecture. However, services currently add more than 65% of global economic value. Designers now face design problems not only in physical systems but transactional as well. This study expands our understanding of design practitioners' cognitive processes by exploring the development of innovative solutions for transactional problems using a DbA approach, via a semantic-word-based ideation method, on a relatively large expert sample size (n ¼ 73) of transactional domain experts. The study shows correlations for semantic solution transfer, quantity of ideation, fixation, novelty and quality when developing solutions for transactional problems by means of DbA methods.

Many natural systems have inspired the design of engineering artifacts. Example systems include a... more Many natural systems have inspired the design of engineering artifacts. Example systems include a broad array of products inspired by pseudo-fractal structures found in nature, including bronchial tubes, watersheds, lightning, and leaf veins. Notably, these systems all resolve a volume-to-point flow problem, i.e., diffusive transportation of heat, energy or fluid into a single flow channel from an initial dispersal throughout a substrate volume (coalescence). Flow diffuses slowly throughout the bulk of the substrate medium towards channels. Once in the channels, flow proceeds rapidly towards the sink. These channels are branched and converge at a single point. Several engineering design problems require a volume-to-point flow solution, e.g., the internal conductive cooling of a microchip. This work introduces a novel geometry-based transport analysis, referred to as path length analysis, for evaluating the performance of systems designed for volume-to-point flow. The analysis is inspired by two principles. First, diffusive flow tends to follow the ''path of least resistance.'' Second, the effort required to diffuse material or energy along a path is proportional to the length of the path. Novel channel configurations may be developed using these two principles. These configurations have a pseudo-fractal type structure and are significantly more efficient than the state-of-the-art for cooling problems such as the conductive cooling of a microchip. An extensive finite element analysis confirms the performance for the example of microchip cooling. The primary results include (1) path length optimization leads to high performing structures with a 'natural' appearance, and (2) path length analysis facilitates a new understanding and design tool for analyzing volume-to-point flow problems.

In product architecture design, designers assign forms to functional elements of the product. Whi... more In product architecture design, designers assign forms to functional elements of the product. While many methods exist to define a product's architecture in terms of modules or platforms, few address the embodiment issues of module interfaces, i.e. the connections between modules. In this paper guidelines for redesign to reduce assembly costs are distilled from a study of existing product layouts. Module interface complexity and number are found to directly affect final costs and a representation scheme is developed to monitor the interface state of a product.

Journal of Mechanical Design, 2010

The bridge between engineering design and cognitive science research is critical to understand th... more The bridge between engineering design and cognitive science research is critical to understand the effectiveness of design methods as implemented by human designers. The study reported in this paper evaluates the effects of design fixation in a group of engineering design faculty, and also provides evidence for approaches to overcome design fixation. Three conditions are compared, a control, a fixation group whom were provided with an example solution, and a defixation group whom were also given materials to mitigate their design fixation. Measures include indicators of design fixation and participant perceptions. The study demonstrates that the engineering design faculty show statistically significant evidence of design fixation, but only partially perceive its effects. This study also indicates that design fixation can be mitigated. The group of participants in this study, due to their background in engineering design research and experience with student design teams, was expected to have more accurate perceptions or awareness of design fixation than the typical participant. Understanding the incongruities between participant perceptions and quantitative design outcomes are particularly of interest to researchers of design methods. For this study, clear evidence exists that designers, even those that study and teach design on a regular basis, do not know when they are being influenced or fixated by misleading or poor information.

Part production requires constant monitoring to assure the effective manufacturing of high-qualit... more Part production requires constant monitoring to assure the effective manufacturing of high-quality components. The choice of monitoring methods can become a crucial factor in the deci- sions made during and prior to manufacturing. In an ideal world, designers and manufacturers will work together to interpre t man- ufacturing and part data to assure the elimination of faults in manufacturing. However,

As more design methodologies are researched and developed, the question arises as to whether thes... more As more design methodologies are researched and developed, the question arises as to whether these new methodologies are actually advancing the field of engineering design or instead cluttering the field with more theories. There is a critical need to test new methodologies for their contribution to the field of design engineering. This paper presents the results of research attempts to substantiate repeatability claims of the functional model derivation method. Three experiments are constructed and carried out with a participant pool that possesses a range of engineering design skill levels. The experiments test the utility of the functional model derivation method to produce repeatable functional models for a given product among different designers. Results indicate the method is largely successful and identify its key strengths as well as opportunities for improvement.

Journal of Manufacturing Science and Engineering-transactions of The Asme, 2000

The status of fault patterns on part surfaces can provide valuable information about the conditio... more The status of fault patterns on part surfaces can provide valuable information about the condition of a manufacturing system. Accurate detection of the part surface condition in manufacturing ensures the fault-free manufacturing of high-quality parts, as well as helping in the accurate design/redesign of machine components and manufacturing parameters. To address this problem, we introduce an alternative mathematical transform that has the potential to detect faults in manufacturing machines by decomposing signals into individual components. Speci cally, the paper focuses on the decomposition of numerically-generated data using the Karhunen-Lo eve transform to study a v ariety of signals from manufacturing. The potential utility of the proposed technique is then discussed in the context of understanding a manufacturing process under constant d e v elopment.

SFF has been instrumental in improving the design process by providing designers with prototypes ... more SFF has been instrumental in improving the design process by providing designers with prototypes that assist them in the communication of design information and design visualization prior to creating fully functional prototypes. Embedding sensors at key locations within an SFF part to extract further data and monitor parameters at critical locations not accessible to ordinary sensors can help immensely in building functional SFF parts. However, this approach requires data acquisition of information such as temperature and strain values from interiors of products. In this work, the authors propose new techniques for embedding thermal sensors and strain gauges into fully dense DuraForm™ during Selective Laser Sintering (SLS) process. The embedded sensors have been used to measure temperatures and strains. They provide higher sensitivity, good accuracy, and high temperature capacity.

Journal of Tribology-transactions of The Asme, 2000

A standard naming convention for mechanical parts is proposed in this paper. We refer to this nam... more A standard naming convention for mechanical parts is proposed in this paper. We refer to this naming convention as the component basis. The component basis is a first step at classifying an exhaustive list of human-made mechanical transmission artifacts as functional forms, geometric shapes, simple machines, and natural forms. The proposed component basis provides a framework for the development of a suite of computational conceptual design tools. This suite of design tools includes a function-based computational concept generator and a product evolution methodology.

Journal of Mechanisms Transmissions and Automation in Design, 1989

A technique to perform design calculations on imprecise representations of parameters has been de... more A technique to perform design calculations on imprecise representations of parameters has been developed and is presented. The level of imprecision in the description of design elements is typically high in the preliminary phase of engineering design. This imprecision is represented using the fuzzy calculus. Calculations can be performed using this method, to produce (imprecise) performance parameters from imprecise (input) design parameters. The Fuzzy Weighted Average technique is used to perform these calculations. A new metric, called the γ-level measure, is introduced to determine the relative coupling between imprecise inputs and outputs. The background and theory supporting this approach are presented, along with one example.

The United States has historically excelled in the design of products, processes and new technolo... more The United States has historically excelled in the design of products, processes and new technologies. Capitalizing on this historical strength to teach applied mathematics and science has many positive implications on education. First, engineering design can be used as a vehicle for addressing deficiencies in mathematics and science education. Second, as achievement in mathematics and science is enhanced, a greater number of students at an earlier age will be exposed to technical career opportunities. Third, enhancing elementary and secondary curricula with engineering design can attract underrepresented populations, such as minorities and females, to engineering as a profession. This paper describes a new and innovative engineering design curriculum, under development in the Austin Independent School District (AISD) in Austin, TX. The philosophic goals upon which the curriculum is based include: integrating the design problem-solving process into elementary schools, demonstrating the relationship of technical concepts to daily life, availing teachers with instructional strategies for teaching applied (as opposed to purely theoretical) science and mathematics, and teaching teamwork skills that are so greatly needed in industry and everyday life. Based on these goals, kindergarten, first grade, and second grade engineering design lessons have been piloted in AISD, in conjunction with a University of Texas program for teacher enhancement and preparation.

The pendulum of engineering education is swinging from an emphasis of theoretical material to a b... more The pendulum of engineering education is swinging from an emphasis of theoretical material to a balance between theory and hands-on activities. This transformation is motivated, in part, by the changing students entering engineering programs. Instead of a tinkering background with the dissection of machines and use of tools, students are now entering with computer, video games, and other "virtual" experiences. This focus has left a void in the ability to relate engineering principles to real-world devices and applications. In this paper, we introduce a new approach for filling this void in a mechanical engineering curriculum. In particular, we describe modifications and extensions to machine design courses to include hands-on exercises. Through the application of "mechanical breadboards," clear relationships between machine design principles and the reality of machine components are established. These relationships reduce the number of topics covered in the courses, but greatly increase the interest of the students and their potential retention of the material.

Successful rehabilitation of transtibial amputees involves effective fitting of prosthetic compon... more Successful rehabilitation of transtibial amputees involves effective fitting of prosthetic components. However, conventional techniques used to produce sockets with suitable characteristics are labor intensive and expensive, and depend on the work of skilled prosthetists that are relatively scarce compared to the number of transtibial amputees. Selective Laser Sintering (SLS) is a very promising technique for producing subject-specific sockets for transtibial amputee prostheses due to its inherent ability to create complex three-dimensional objects directly from digital shape information without the need for specific tooling, molds or human labor. This dissertation presents a framework for the design, analysis, manufacture and testing of SLS sockets for transtibial prostheses, including the development of a computer-aided design model of the socket with compliant features to enhance comfort, structural analysis using a Finite Element Method (FEM) model, fabrication of a functional prototype using SLS, and experimental validation of the FEM analysis. The validation involved quantifying the failing conditions of sockets manufactured using the vii framework during destructive tests. The experimental failure loads for the sockets were within a 3% range of the FEM results and were considered satisfactory. The specific design of orthogonally compliant features for socket was also analyzed. This process included the preliminary evaluation of design alternatives using FEM with validation through experimental measurements, definition of specific design methodology for the best alternatives, incorporation of solution within the socket and refinement of design using auxiliary features obtained through topology optimization. Finally, to investigate the structural response of the SLS socket during gait, a FEM model (acquired from Computed Tomography data of a transtibial amputee) composed of a socket, liner and residual limb under quasi-static loading derived from typical ground reaction forces was employed. Three different compliant designs were evaluated to assess their ability to locally relieve local pressure during the stance phase of gait, as well as their structural integrity to ensure safety. The design with a compliant feature consisting of spiral slots within the socket wall was determined to produce a local average relief of 65.8% in the interface pressure, reducing the peak pressure from 172 kPa to 66.4 kPa.

Design-by-analogy is well-recognized for its power in innovation processes. Understanding the cog... more Design-by-analogy is well-recognized for its power in innovation processes. Understanding the cognitive processes involved in the formation of analogies is important for understanding the concept generation process. This paper takes a distinctive interdisciplinary route to combine research in cognitive psychology and design to develop a more complete understanding design-by-analogy and to provide the basis for formal method development.

Fuzzy Sets and Systems, 1992

Uncertainty in engineering analysis usually pertains to stochastic uncertainty, i.e., variance in... more Uncertainty in engineering analysis usually pertains to stochastic uncertainty, i.e., variance in product or process parameters characterized by probability (uncertainty in truth). Methods for calculating under stochastic uncertainty are well documented. It has been proposed by the authors that other forms of uncertainty exist in engineering design. Imprecision, or the concept of uncertainty in choice, is one such form. This paper considers real-time techniques for calculating with imprecise parameters. These techniques utilize interval mathematics and the notion of α-cuts from the fuzzy calculus. The extremes or anomalies of the techniques are also investigated, particularly the evaluation of singular or multi-valued functions. It will be shown that realistic engineering functions can be used in imprecision calculations, with reasonable computational performance. etc., are not specified or known. Conventional computer-aided design methods require highly precise descriptions in order to operate, making them difficult or impossible to use during the early design process. This research focuses on the development of methods for representing and manipulating imprecise descriptions of designs to provide the designer with more information to compare alternatives during the preliminary design phase.

New products drive business. To remain competitive, industry is continually searching for new met... more New products drive business. To remain competitive, industry is continually searching for new methods to evolve their products. To address this need, we introduce a new reverse engineering and redesign methodology. Motivation is provided by the S-curve product improvement history. We start by formulating the customer needs, followed by reverse engineering, creating a functional model through teardowns. The functional model leads to specifications that match the customer needs. Depending upon required redesign scope, new features are possibly conceived, or not. Next models of the specifications are developed and optimized. The new product form is then built and further optimized using designed experiments. An electric wok redesign provides an illustration. The methodology has had a positive impact in results and systematic approach, both on design education and application.

Journal of Mechanical Design, 1995

The submacrogeometric (tolerance) variations of mechanical components have an important impact on... more The submacrogeometric (tolerance) variations of mechanical components have an important impact on product function. The problem of combining tolerance assignment in engineering design with tolerance control in manufacturing and quality assurance presents a continuing challenge to researchers. This paper illustrates the feasibility of using fractal-based methods for the problem of tolerance specification in engineering design. Error data are generated as a function of the fractal dimension using the fractional Brownian motion model and are superposed on an ideal profile of a slider bearing. The consequent changes in performance parameters are studied and the detrimental effect of large variations perceived. This simple case study indicates the potential of the method to be extended for more complex problems. YH(X), let the mean square increment in YH(X) for points a distance Ax = 1 from one another be a 2, where a is the standard

Design fixation is a phenomenon that can negatively impact design outcomes, especially when it oc... more Design fixation is a phenomenon that can negatively impact design outcomes, especially when it occurs during the ideation stage of a design process. This study expands our understanding of design fixation by presenting a review of approaches that report its reduction or elimination, as well as metrics employed to understand and account for design fixation. The study then explores the relevant ideation area of Design-by-Analogy (DbA), with a fixation experiment with 73 knowledge-domain experts to overcome design fixation. The study provides a design fixation framework and constitutes a genuine contribution to effectively identify design fixation mitigating approaches in a wide range of design problems, and provides concrete evidence of cognitive mechanisms to overcome fixation.

Design-by-Analogy (DbA) is recognized for its potential for fostering innovation. Previous work p... more Design-by-Analogy (DbA) is recognized for its potential for fostering innovation. Previous work provides insights into how analogies assist in solving problems in engineering design and architecture. However, services currently add more than 65% of global economic value. Designers now face design problems not only in physical systems but transactional as well. This study expands our understanding of design practitioners' cognitive processes by exploring the development of innovative solutions for transactional problems using a DbA approach, via a semantic-word-based ideation method, on a relatively large expert sample size (n ¼ 73) of transactional domain experts. The study shows correlations for semantic solution transfer, quantity of ideation, fixation, novelty and quality when developing solutions for transactional problems by means of DbA methods.

Many natural systems have inspired the design of engineering artifacts. Example systems include a... more Many natural systems have inspired the design of engineering artifacts. Example systems include a broad array of products inspired by pseudo-fractal structures found in nature, including bronchial tubes, watersheds, lightning, and leaf veins. Notably, these systems all resolve a volume-to-point flow problem, i.e., diffusive transportation of heat, energy or fluid into a single flow channel from an initial dispersal throughout a substrate volume (coalescence). Flow diffuses slowly throughout the bulk of the substrate medium towards channels. Once in the channels, flow proceeds rapidly towards the sink. These channels are branched and converge at a single point. Several engineering design problems require a volume-to-point flow solution, e.g., the internal conductive cooling of a microchip. This work introduces a novel geometry-based transport analysis, referred to as path length analysis, for evaluating the performance of systems designed for volume-to-point flow. The analysis is inspired by two principles. First, diffusive flow tends to follow the ''path of least resistance.'' Second, the effort required to diffuse material or energy along a path is proportional to the length of the path. Novel channel configurations may be developed using these two principles. These configurations have a pseudo-fractal type structure and are significantly more efficient than the state-of-the-art for cooling problems such as the conductive cooling of a microchip. An extensive finite element analysis confirms the performance for the example of microchip cooling. The primary results include (1) path length optimization leads to high performing structures with a 'natural' appearance, and (2) path length analysis facilitates a new understanding and design tool for analyzing volume-to-point flow problems.

In product architecture design, designers assign forms to functional elements of the product. Whi... more In product architecture design, designers assign forms to functional elements of the product. While many methods exist to define a product's architecture in terms of modules or platforms, few address the embodiment issues of module interfaces, i.e. the connections between modules. In this paper guidelines for redesign to reduce assembly costs are distilled from a study of existing product layouts. Module interface complexity and number are found to directly affect final costs and a representation scheme is developed to monitor the interface state of a product.

Journal of Mechanical Design, 2010

The bridge between engineering design and cognitive science research is critical to understand th... more The bridge between engineering design and cognitive science research is critical to understand the effectiveness of design methods as implemented by human designers. The study reported in this paper evaluates the effects of design fixation in a group of engineering design faculty, and also provides evidence for approaches to overcome design fixation. Three conditions are compared, a control, a fixation group whom were provided with an example solution, and a defixation group whom were also given materials to mitigate their design fixation. Measures include indicators of design fixation and participant perceptions. The study demonstrates that the engineering design faculty show statistically significant evidence of design fixation, but only partially perceive its effects. This study also indicates that design fixation can be mitigated. The group of participants in this study, due to their background in engineering design research and experience with student design teams, was expected to have more accurate perceptions or awareness of design fixation than the typical participant. Understanding the incongruities between participant perceptions and quantitative design outcomes are particularly of interest to researchers of design methods. For this study, clear evidence exists that designers, even those that study and teach design on a regular basis, do not know when they are being influenced or fixated by misleading or poor information.

Part production requires constant monitoring to assure the effective manufacturing of high-qualit... more Part production requires constant monitoring to assure the effective manufacturing of high-quality components. The choice of monitoring methods can become a crucial factor in the deci- sions made during and prior to manufacturing. In an ideal world, designers and manufacturers will work together to interpre t man- ufacturing and part data to assure the elimination of faults in manufacturing. However,

As more design methodologies are researched and developed, the question arises as to whether thes... more As more design methodologies are researched and developed, the question arises as to whether these new methodologies are actually advancing the field of engineering design or instead cluttering the field with more theories. There is a critical need to test new methodologies for their contribution to the field of design engineering. This paper presents the results of research attempts to substantiate repeatability claims of the functional model derivation method. Three experiments are constructed and carried out with a participant pool that possesses a range of engineering design skill levels. The experiments test the utility of the functional model derivation method to produce repeatable functional models for a given product among different designers. Results indicate the method is largely successful and identify its key strengths as well as opportunities for improvement.

Journal of Manufacturing Science and Engineering-transactions of The Asme, 2000

The status of fault patterns on part surfaces can provide valuable information about the conditio... more The status of fault patterns on part surfaces can provide valuable information about the condition of a manufacturing system. Accurate detection of the part surface condition in manufacturing ensures the fault-free manufacturing of high-quality parts, as well as helping in the accurate design/redesign of machine components and manufacturing parameters. To address this problem, we introduce an alternative mathematical transform that has the potential to detect faults in manufacturing machines by decomposing signals into individual components. Speci cally, the paper focuses on the decomposition of numerically-generated data using the Karhunen-Lo eve transform to study a v ariety of signals from manufacturing. The potential utility of the proposed technique is then discussed in the context of understanding a manufacturing process under constant d e v elopment.

SFF has been instrumental in improving the design process by providing designers with prototypes ... more SFF has been instrumental in improving the design process by providing designers with prototypes that assist them in the communication of design information and design visualization prior to creating fully functional prototypes. Embedding sensors at key locations within an SFF part to extract further data and monitor parameters at critical locations not accessible to ordinary sensors can help immensely in building functional SFF parts. However, this approach requires data acquisition of information such as temperature and strain values from interiors of products. In this work, the authors propose new techniques for embedding thermal sensors and strain gauges into fully dense DuraForm™ during Selective Laser Sintering (SLS) process. The embedded sensors have been used to measure temperatures and strains. They provide higher sensitivity, good accuracy, and high temperature capacity.

Journal of Tribology-transactions of The Asme, 2000

A standard naming convention for mechanical parts is proposed in this paper. We refer to this nam... more A standard naming convention for mechanical parts is proposed in this paper. We refer to this naming convention as the component basis. The component basis is a first step at classifying an exhaustive list of human-made mechanical transmission artifacts as functional forms, geometric shapes, simple machines, and natural forms. The proposed component basis provides a framework for the development of a suite of computational conceptual design tools. This suite of design tools includes a function-based computational concept generator and a product evolution methodology.

Journal of Mechanisms Transmissions and Automation in Design, 1989

A technique to perform design calculations on imprecise representations of parameters has been de... more A technique to perform design calculations on imprecise representations of parameters has been developed and is presented. The level of imprecision in the description of design elements is typically high in the preliminary phase of engineering design. This imprecision is represented using the fuzzy calculus. Calculations can be performed using this method, to produce (imprecise) performance parameters from imprecise (input) design parameters. The Fuzzy Weighted Average technique is used to perform these calculations. A new metric, called the γ-level measure, is introduced to determine the relative coupling between imprecise inputs and outputs. The background and theory supporting this approach are presented, along with one example.

The United States has historically excelled in the design of products, processes and new technolo... more The United States has historically excelled in the design of products, processes and new technologies. Capitalizing on this historical strength to teach applied mathematics and science has many positive implications on education. First, engineering design can be used as a vehicle for addressing deficiencies in mathematics and science education. Second, as achievement in mathematics and science is enhanced, a greater number of students at an earlier age will be exposed to technical career opportunities. Third, enhancing elementary and secondary curricula with engineering design can attract underrepresented populations, such as minorities and females, to engineering as a profession. This paper describes a new and innovative engineering design curriculum, under development in the Austin Independent School District (AISD) in Austin, TX. The philosophic goals upon which the curriculum is based include: integrating the design problem-solving process into elementary schools, demonstrating the relationship of technical concepts to daily life, availing teachers with instructional strategies for teaching applied (as opposed to purely theoretical) science and mathematics, and teaching teamwork skills that are so greatly needed in industry and everyday life. Based on these goals, kindergarten, first grade, and second grade engineering design lessons have been piloted in AISD, in conjunction with a University of Texas program for teacher enhancement and preparation.

The pendulum of engineering education is swinging from an emphasis of theoretical material to a b... more The pendulum of engineering education is swinging from an emphasis of theoretical material to a balance between theory and hands-on activities. This transformation is motivated, in part, by the changing students entering engineering programs. Instead of a tinkering background with the dissection of machines and use of tools, students are now entering with computer, video games, and other "virtual" experiences. This focus has left a void in the ability to relate engineering principles to real-world devices and applications. In this paper, we introduce a new approach for filling this void in a mechanical engineering curriculum. In particular, we describe modifications and extensions to machine design courses to include hands-on exercises. Through the application of "mechanical breadboards," clear relationships between machine design principles and the reality of machine components are established. These relationships reduce the number of topics covered in the courses, but greatly increase the interest of the students and their potential retention of the material.

Successful rehabilitation of transtibial amputees involves effective fitting of prosthetic compon... more Successful rehabilitation of transtibial amputees involves effective fitting of prosthetic components. However, conventional techniques used to produce sockets with suitable characteristics are labor intensive and expensive, and depend on the work of skilled prosthetists that are relatively scarce compared to the number of transtibial amputees. Selective Laser Sintering (SLS) is a very promising technique for producing subject-specific sockets for transtibial amputee prostheses due to its inherent ability to create complex three-dimensional objects directly from digital shape information without the need for specific tooling, molds or human labor. This dissertation presents a framework for the design, analysis, manufacture and testing of SLS sockets for transtibial prostheses, including the development of a computer-aided design model of the socket with compliant features to enhance comfort, structural analysis using a Finite Element Method (FEM) model, fabrication of a functional prototype using SLS, and experimental validation of the FEM analysis. The validation involved quantifying the failing conditions of sockets manufactured using the vii framework during destructive tests. The experimental failure loads for the sockets were within a 3% range of the FEM results and were considered satisfactory. The specific design of orthogonally compliant features for socket was also analyzed. This process included the preliminary evaluation of design alternatives using FEM with validation through experimental measurements, definition of specific design methodology for the best alternatives, incorporation of solution within the socket and refinement of design using auxiliary features obtained through topology optimization. Finally, to investigate the structural response of the SLS socket during gait, a FEM model (acquired from Computed Tomography data of a transtibial amputee) composed of a socket, liner and residual limb under quasi-static loading derived from typical ground reaction forces was employed. Three different compliant designs were evaluated to assess their ability to locally relieve local pressure during the stance phase of gait, as well as their structural integrity to ensure safety. The design with a compliant feature consisting of spiral slots within the socket wall was determined to produce a local average relief of 65.8% in the interface pressure, reducing the peak pressure from 172 kPa to 66.4 kPa.

Design-by-analogy is well-recognized for its power in innovation processes. Understanding the cog... more Design-by-analogy is well-recognized for its power in innovation processes. Understanding the cognitive processes involved in the formation of analogies is important for understanding the concept generation process. This paper takes a distinctive interdisciplinary route to combine research in cognitive psychology and design to develop a more complete understanding design-by-analogy and to provide the basis for formal method development.

Fuzzy Sets and Systems, 1992

Uncertainty in engineering analysis usually pertains to stochastic uncertainty, i.e., variance in... more Uncertainty in engineering analysis usually pertains to stochastic uncertainty, i.e., variance in product or process parameters characterized by probability (uncertainty in truth). Methods for calculating under stochastic uncertainty are well documented. It has been proposed by the authors that other forms of uncertainty exist in engineering design. Imprecision, or the concept of uncertainty in choice, is one such form. This paper considers real-time techniques for calculating with imprecise parameters. These techniques utilize interval mathematics and the notion of α-cuts from the fuzzy calculus. The extremes or anomalies of the techniques are also investigated, particularly the evaluation of singular or multi-valued functions. It will be shown that realistic engineering functions can be used in imprecision calculations, with reasonable computational performance. etc., are not specified or known. Conventional computer-aided design methods require highly precise descriptions in order to operate, making them difficult or impossible to use during the early design process. This research focuses on the development of methods for representing and manipulating imprecise descriptions of designs to provide the designer with more information to compare alternatives during the preliminary design phase.

New products drive business. To remain competitive, industry is continually searching for new met... more New products drive business. To remain competitive, industry is continually searching for new methods to evolve their products. To address this need, we introduce a new reverse engineering and redesign methodology. Motivation is provided by the S-curve product improvement history. We start by formulating the customer needs, followed by reverse engineering, creating a functional model through teardowns. The functional model leads to specifications that match the customer needs. Depending upon required redesign scope, new features are possibly conceived, or not. Next models of the specifications are developed and optimized. The new product form is then built and further optimized using designed experiments. An electric wok redesign provides an illustration. The methodology has had a positive impact in results and systematic approach, both on design education and application.

Journal of Mechanical Design, 1995

The submacrogeometric (tolerance) variations of mechanical components have an important impact on... more The submacrogeometric (tolerance) variations of mechanical components have an important impact on product function. The problem of combining tolerance assignment in engineering design with tolerance control in manufacturing and quality assurance presents a continuing challenge to researchers. This paper illustrates the feasibility of using fractal-based methods for the problem of tolerance specification in engineering design. Error data are generated as a function of the fractal dimension using the fractional Brownian motion model and are superposed on an ideal profile of a slider bearing. The consequent changes in performance parameters are studied and the detrimental effect of large variations perceived. This simple case study indicates the potential of the method to be extended for more complex problems. YH(X), let the mean square increment in YH(X) for points a distance Ax = 1 from one another be a 2, where a is the standard