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Engineering design often involves representation in at least two levels of abstraction: the system-level, represented by lumped parameter models (LPMs), and the geometric-level, represented by distributed parameter models (DPMs). Functional design innovation commonly occurs at the system-level, followed by a geometric-level realization of functional LPM components. However, comparing these two levels in terms of behavioral outcomes can be challenging and time-consuming, leading to delays in design translations between system and mechanical engineers. In this paper, we propose a simulation-free scheme that compares LPMs and spatially discretized DPMs based on their model specifications and behaviors of interest, regardless of modeling languages and numerical methods. We adopt a model order reduction (MOR) technique that a priori guarantees accuracy, stability, and convergence to improve the computational efficiency of large-scale models. Our approach is demonstrated through the model consistency analysis of several mechanical designs, showing its validity, efficiency, and generality. Our method provides a systematic way to compare system-level and geometric-level designs, improving reliability and facilitating design translation. [ABSTRACT FROM AUTHOR]

As computer-aided design (CAD) tools have become an essential aspect of modern mechanical engineering design, the demand for CAD experts has increased significantly. The development from novice, to proficient, to expert user is of particular interest to the industrial and academic design communities. Yet little is known about the development of modeling choices, strategies, and patterns that characterize expert CAD skills; much of the past work that reports user action data is based on student or novice data. We compared the CAD modeling process across nine proficient and ten expert designers as they were tested to complete the same design task. Under identical conditions-the same time constraints in the same CAD platform and with the same task-the expert users were able to complete a larger proportion of the task with higher dimensional accuracy. While the experts were able to dissect and retrieve geometries from manufacturing drawings more efficiently than proficient users, they were also able to plan a modeling strategy that required less effort and revisions. With our experimental findings, we identify the demand for procedural knowledge-building for young engineers, with the ultimate goal of more effectively developing experts in engineering design with CAD. [ABSTRACT FROM AUTHOR]

As the most prestigious award in the field of machine design, the ASME Machine Design Award relishes its prestige and prominence. In the past 65 years since its inception in 1958, 60 eminent scholars have received this honor. This paper reviews the history of this prestigious award, including a summary of the contributions to the field of all 60 recipients, and acts as an archival document. Reviewing these awards in the past 65 years by following the tracks of its recipients elucidates developments in the field and significant contributions to the advancement of knowledge in machine design. In particular, novel contributions and remarkable achievements in the fields of mechanical engineering and machine design and development are recorded. This should be of interest to those interested in the study and in the historical development of mechanical engineering, particularly in machine design. [ABSTRACT FROM AUTHOR]

Prototyping is an important part of the design process, but researchers currently have a limited understanding of how the resources invested in a prototype or designer teams' intent for a prototype influence decision-making and perceptions of a prototype's value. Prior work has shown that significant investment of time or money in design tasks can lead to design fixation, but little work has explored how these factors might impact design teams' perceived value of prototypes with respect to the design process. Likewise, it is unclear how resource allocation and prototype intention effects the evolution of design team knowledge and subsequent design actions. To explore these relationships, an in situ study of prototyping tendencies was performed across two mechanical engineering design courses. Results suggest that effective design teams leveraged prototypes to uncover new design knowledge and limit uncertainty early in the design process. Importantly, this study did not find any significant relationships between the cost of a prototype in terms of money and time, and the perceived value of that prototype. Nor were any significant relationships found between costs and final design outcomes. Findings suggest that the true cost and value of a prototype with respect to design outcomes are challenging to explicitly quantify. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) processes offer unique capabilities (i.e., opportunities) yet inherent limitations (i.e., restrictions) due to the layer-by-layer fabrication of parts. Despite the newfound design freedom and increased use of AM, limited research has investigated how knowledge of the AM processes affects the creativity of students' ideas after being exposed to AM. This study investigates this gap through an experimental study with 343 participants recruited from a junior-level mechanical engineering design course. The participants were exposed to three variations in design for additive manufacturing (DfAM) education: (1) no DfAM, (2) restrictive DfAM, and (3) opportunistic and restrictive (dual) DfAM education. The effects of these three interventions were measured through differences in (1) participants' self-reported use of DfAM in a design challenge and (2) expert assessment of the creativity of the outcomes from the said design challenge. The results of the study indicated that variations in DfAM content did not result in differences in the participants' self-reported use of either opportunistic or restrictive DfAM, with all three groups reporting similar levels of emphasis. Further, participants from all three groups reported higher use of restrictive DfAM techniques, compared with opportunistic DfAM. Moreover, while variations in the content had no effect on the creativity (uniqueness and usefulness) of the participants' design outcomes, teaching both opportunistic and restrictive DfAM did result in the generation of designs with greater AM technical goodness--a novel and significant finding in our study. The results of this study highlight the need for DfAM educational interventions that encourage students to not only learn about but also integrate both opportunistic and restrictive concepts effectively into their creative design process. This would result in the generation of innovative products that leverage the design freedom enabled by AM, yet addressing the limitations inherent in the process. [ABSTRACT FROM AUTHOR]

Research in additive manufacturing (AM) has increased the use of AM in many industries, resulting in a commensurate need for a workforce skilled in AM. In order to meet this need, educational institutions have undertaken different initiatives to integrate design for additive manufacturing (DfAM) into the engineering curriculum. However, limited research has explored the impact of these educational interventions in bringing about changes in the technical goodness of students' design outcomes, particularly through the integration of DfAM concepts in an engineering classroom environment. This study explores this gap using an experimental study with 193 participants recruited from a junior-level course on mechanical engineering design. The participants were split into three educational intervention groups: (1) no DfAM, (2) restrictive DfAM, and (3) restrictive and opportunistic (dual) DfAM. The effects of the educational intervention on the participants' use of DfAM were measured through changes in (1) participants' DfAM self-efficacy, (2) technical goodness of their AM design outcomes, and (3) participants' use of DfAM-related concepts when describing and evaluating their AM designs. The results showed that while all three educational interventions result in similar changes in the participants' opportunistic DfAM self-efficacy, participants who receive only restrictive DfAM inputs show the greatest increase in their restrictive DfAM self-efficacy. Further, we see that despite these differences, all three groups show a similar decrease in the technical goodness of their AM designs, after attending the lectures. A content analysis of the participants' design descriptions and evaluations revealed a simplification of their design geometries, which provides a possible explanation for the decrease in their technical goodness, despite the encouragement to utilize the design freedom of AM to improve functionality or optimize the weight of the structure. These results emphasize the need for more in-depth DfAM education to encourage the use of both opportunistic and restrictive DfAM during student design challenges. The results also highlight the possible influence of how the design problem is stated on the use of DfAM in solving it. [ABSTRACT FROM AUTHOR]

Although morphological charts are widely taught used tools in engineering design, little formal guidance is provided regarding their representation and exploration. Thus, an experiment was conducted to elucidate the influence of functional ordering on the exploration of morphological charts. Two design prompts were used, each with five different functional arrangements: (1) most-to-least important function, (2) least-to-most important function, (3) input-to-output function, (4) output-to-input function, and (5) Random. Sixty-seven junior mechanical engineering students were asked to generate integrated design concepts from prepopulated morphological charts for each design prompt. The concepts were analyzed to determine the frequency with which a given means was selected, how much of the chart was explored, the sequence of exploration, and the influence of function ordering. Results indicated a tendency to focus upon the initial columns of the chart irrespective of functional order. The most-to-least-important functional order resulted in higher chances and a uniformity of design space exploration. [ABSTRACT FROM AUTHOR]

A significant gap exists between engineering students' perceptions of prototypes and prototyping abilities and professionals' perceptions and abilities. Structured prototyping frameworks have recently been developed and proposed as a means to help students close this gap, but the effects of these frameworks on students' behavior have not been assessed. The purpose of this work is to investigate if and how a structured prototyping framework affects the self-reported prototyping behaviors of engineering students. Understanding how structured prototyping frameworks affect students can provide educators with a deeper understanding of the way their students adopt and understand design methods. A mixed method study is presented. A 15-item survey and two open-ended questions were distributed to 235 students in a junior-level mechanical engineering design class in order to capture self-reported prototyping behavior. Quantitative results indicate that significant differences in engineering students' prototyping behaviors exist across time and between groups. Results from qualitative analysis indicate that students in the control group focused solely on improving technical quality, while students in both experimental groups focused on a wider range of design qualities. This study is the first to demonstrate that a structured prototyping framework can affect engineering students' self-reported prototyping behaviors during design activities. [ABSTRACT FROM AUTHOR]

We have observed that many designers use spreadsheet programs for preliminary parametric design calculations. The primary reason for this appears to be the flexibility and ease of use of spreadsheets as compared to more advanced analysis tools. However, current commercially available spreadsheets were originally designed for finance and accounting and do not naturally support the analytical techniques used in design and engineering. In this paper, we propose a fundamentally different kind of spreadsheet for use in preliminary parametric design. We describe the features of this spreadsheet that make it especially suitable for preliminary parametric design, discuss the theoretical basis for implementing it and present the results of preliminary user tests.

Design and other fundamental topics in engineering are often isolated to dedicated courses. An opportunity exists to foster a culture of engineering design and multidisciplinary problem solving throughout the curriculum. Designettes, charettelike design challenges, are rapid and creative learning tools that enable educators to integrate design learning in a single class, across courses, across terms, and across disciplines. When two or more courses join together in a designette, a multidisciplinary learning activity occurs; multiple subjects are integrated and applied to open-ended problems and grand challenges. This practice helps foster a culture of design, and enables the introduction of multidisciplinary design challenges. Studies at the Singapore University of Technology and Design (SUTD) demonstrate learning of engineering subject matter in a bio-inspired robotics designette (MechAnimal), an interactive musical circuit designette, and an automated milk delivery (AutoMilk) designette. Each challenge combines problem clarification, concept generation, and prototyping with subject content such as circuits, biology, thermodynamics, differential equations, or software with controls. From pre- and postsurveys of students, designettes are found to increase students' understanding of engineering concepts. From 321 third-semester students, designettes were found to increase students' perceptions of their ability to solve multidisciplinary problems. [ABSTRACT FROM AUTHOR]

In this research, the interpretability of function structures is evaluated through a user study in which participants are given function structures and asked to identify the product that is modeled. Two abstraction factors are controlled in the experiment: the type of functions and the specificity of the terms, thus resulting in functional models are four level of abstraction. The user study shows that free language significantly improves the accuracy and speed of human interpretability over the functional basis vocabulary. Further, pruned function structures significantly improve the speed of interpretability over reverse-engineered function structures without a loss of accuracy. It is concluded that the levels of each factor are useful for different activities and stages of design. Recommendations are made for the appropriate combinations of factor levels for various design activities. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach, referred to as the WordTree design-by-analogy method, for identifying distant-domain analogies as part of the ideation process. The WordTree method derives its effectiveness through a design team’s knowledge and readily available information sources (e.g., patent databases, Google) and does not require specialized computational knowledge bases. A controlled cognitive experiment and an evaluation of the method with redesign projects illustrate the method’s influence in assisting engineers in design-by-analogy. Individuals using the WordTree method identified significantly more analogies and searched outside the problem domain as compared to the control group. The team redesign projects demonstrate the WordTree method’s effectiveness in longer-term, more realistic, higher validity team projects and with a variety of different design problems. Teams successfully identified effective analogies, analogous domains, and analogous patents. Unexpected and unique solutions are identified using the method. For example, one of the teams identified a dump truck and panning for gold as effective analogies for the design of a self-cleaning cat litter box. In the controlled experiment, a cherry pitter was identified and implemented as a solution for designing a machine to shell peanuts. The experimental results also highlight potential improvements for the method and areas for future research in engineering design theory. [ABSTRACT FROM AUTHOR]

The essential function of a mechanical assembly is the removal of degrees of freedom (DOF) to enable the transfer of load between two bodies. Assembly constraint features serve to provide this DOF removal, so their locations and orientations greatly affect the quality of an assembly as measured by its ability to resist relative motion between the parts. This paper addresses attachment-level design in which design decisions are made to establish the types, locations, and orientations of assembly features. The analysis methodology in this paper models assembly features such as point, pin, line, and plane constraints with equivalent first, second, and third order wrench systems. The set of relative motions to be evaluated is generated by composing from among these constraints a five-system pivot wrench combination to which a freedom screw motion is reciprocal. The effectiveness of each constraint to resist these motions is calculated as the ratio of the reaction forces at each resisting constraint to the input wrench magnitude. Based on these resistance values, multiple rating metrics are calculated to rate the overall assembly’s performance in resisting the motion. This work represents the first tool available to analyze a constraint configuration’s effectiveness to resist motion with a quantitative metric. Case studies are presented to demonstrate the utility of the analysis tool. [ABSTRACT FROM AUTHOR]

This paper presents proposed designs of parallel hybrid transmissions with only one electric motor/generator (MG) and without any rotating clutches. The proposed motor/generator integrated hybrid transmission serves to regulate the engine’s effective gear ratio (engine rotational velocity versus vehicle velocity) by mixing the engine and electric motor powers through a power controlling device. The proposed design provides some of the benefits and flexibility of a power-split design but using conventional available components in a simpler mechanical layout that makes the design compact, mechanically simple, and operationally flexible. Three commonly used transmission gear sets are used for this purpose; Simpson, Ravigneaux, and Type-6206 gear sets. With an electronic control unit, eight major modes of operation including a regenerative braking capability are shown to be feasible in the proposed hybrid transmission; one electric motor mode, two engine modes, two engine/charge modes, and two power modes. Continuously variable transmission (CVT) capability is provided with the second engine/charge mode and with the second power mode. The second power mode can be further subdivided into three hybrid submodes that correspond to the direct drive, underdrive, and overdrive of a conventional automatic transmission. The feasibility of the proposed hybrid transmission is demonstrated with a numerical example employing conventional Ravigneaux gear train. The kinematics, static torque, and power flow relations for all operation modes are analyzed in detail. [ABSTRACT FROM AUTHOR]

The mechanism for the planetary motions contained in the lost subsystem of Antikythera mechanism is a strict challenge of the reconstruction design. This work presents a systematic procedure of the reconstruction design to synthesize all feasible designs which agree with the science and technology standards of the subject’s time period. Based on the kinematic analysis of ancient planetary theories, the anomaly planetary motions could be formulated. By the mechanism analysis, two types of feasible topological structures with the minimum numbers of members are obtained, and the relationships of teeth for the inferior and superior planets are derived. Through the study of the historical literature, the astronomical theories and the existing designs, the required design constraints are concluded. For the two reconstruction designs, one, the design by Edmunds and Morgan, and three feasible design concepts are, respectively, synthesized in accordance with the concepts of generalization and specialization. Focusing on each feasible design concepts, this work derives the relationships of teeth. Furthermore, one feasible combination of these feasible designs for different planets is adopted for detail design. And, it could be the original structure for the planetary motions of the lost subsystem of Antikythera mechanism. [ABSTRACT FROM AUTHOR]

Wikis, freely editable collections of web pages, exhibit potential for a flexible documentation and communication tool for collaborative design tasks as well as support for team design thinking early in the design process. The purpose of this work is to analyze dimensions of wiki technologies from a communication perspective as applicable to design. A wiki was introduced in a globally distributed product development course, and the experiences and performance of colocated and distributed teams in the course were assessed through observations, surveys, and site usage analytics. With a focus on communication in design, we explore the advantages and disadvantages of using wikis in student engineering design teams. Our goal is to use wiki technologies to enhance support for design processes while exploiting the potential for increasing shared understanding among teams. Distributed teams used the wiki more as a design tool and were more supportive of its use in the course whereas colocated teams used it for documentation. The usage patterns, the number and type of files uploaded, and the wiki structure provided indicators of better performing teams. The findings also suggest ways to improve and inform students about best practices using the wiki for design and to transform the wiki as a support tool for communication during early design collaboration. [ABSTRACT FROM AUTHOR]

Mechanical engineers and those in related fields require effective written communication skills. These include the appropriate presentation of mechanical design information in visual format. A study of 48 Capstone Design Reports submitted over a period of five semesters gives insight into the visual representations used to describe designs. This study presents observations on the use of visuals in a set of Capstone Design Reports with particular emphasis on sketches. The findings are that students will include hand drawn sketches of design alternatives during the conceptual design process when specifically required to do so. The sketches tend not to be of high quality artistically but they do include details relevant to engineering analysis as determined by a coding scheme focused on the content level of sketches. The authors believe that the positive benefits of sketching should be encouraged by requiring students to produce hand drawn sketches and accepting sketches as visuals in concept generation design sections of design reports. [ABSTRACT FROM AUTHOR]

Emerging applications of ball screw drives such as semiconductor inspection, fiber optic alignment, medical equipment, and miniature robotic actuators typically make use of ball screws that are compact, stiff, and precise. Existing models for the screw–nut interface stiffness of ball screw drives are however unable to accurately describe the dynamics of compact and stiff ball screws because they are derived based on the assumption that the portion of the screw within the nut is rigid. This paper proposes a new screw–nut interface stiffness model, which incorporates the elastic deformation of the screw within the nut using Timoshenko beam shape functions. The new model is shown, via simulation and experiments, to provide more accurate predictions of the natural frequencies of compact and stiff ball screwnut assemblies compared to the existing models. It is therefore more suitable for use in the design simulationevaluation of high-performance ball screw drives where compactness and rigidity are required. [ABSTRACT FROM AUTHOR]

Advances in innovation processes are critically important as economic and business landscapes evolve. There are many concept generation techniques that can assist a designer in the initial phases of design. Unfortunately, few studies have examined these techniques that can provide evidence to suggest which techniques should be preferred or how to implement them in an optimal way. This study systematically investigates the underlying factors of four common and well-documented techniques: brainsketching, gallery, 6-3-5, and C-sketch. These techniques are resolved into their key parameters, and a rigorous factorial experiment is performed to understand how the key parameters affect the outcomes of the techniques. The factors chosen for this study with undergraduate mechanical engineers include how concepts are displayed to participants (all are viewed at once or subsets are exchanged between participants, i.e., “rotational viewing”) and the mode used to communicate ideas (written words only, sketches only, or a combination of written words and sketches). Four metrics are used to evaluate the data: quantity, quality, novelty, and variety. The data suggest that rotational viewing of sets of concepts described using sketches combined with words produces more ideas than having all concepts displayed in a “gallery view” form, but a gallery view results in more high quality concepts. These results suggest that a hybrid of methods should be used to maximize the quality and number of ideas. The study also shows that individuals gain a significant number of ideas from their teammates. Ideas, when shared, can foster new idea tracks, more complete layouts, and a diverse synthesis. Finally, as teams develop more concepts, the quality of the concepts improves. This result is a consequence of the team-sharing environment and, in conjunction with the quantity of ideas, validates the effectiveness of group idea generation. This finding suggests a way to go beyond the observation that some forms of brainstorming can actually hurt productivity. [ABSTRACT FROM AUTHOR]

This paper develops new design criteria for lamina emergent mechanism (LEM) flexures with particular application to sheet-metal-formed metal flexures. The LEM flexure design criteria are based on the relative performance between the LEM flexure and a section of lamina that is of the same overall length, width, and thickness as the LEM flexure. Novel metal revolute and torsional LEM flexures are presented and evaluated against the LEM flexure design criteria. Both flexures meet the proposed criteria, and their performance is evaluated in the design of a basic crank-slider mechanism. When compared with unformed flexures of the same dimensions, the revolute and torsional metal LEM flexures are found to improve the crank-slider performance. [ABSTRACT FROM AUTHOR]

Quantification of subjective attributes expressed as functions of design variables is a significant challenge in creating product design optimization models. For example, the objective assessment of a vehicle’s environmental friendliness is typically based on fuel economy and emissions. But some design variables such as a vehicle’s silhouette (two-dimensional body shape) may create a subjective perception of environmental friendliness, which may impact consumer preference along with objective metrics. In this paper, we show a method for assessing subjective attributes in the context of design attributes. We focus on perceived environmental friendliness (PEF) and we develop a model of PEF as a function of vehicle silhouette shape variables. The modeling process consists of stimuli development using design of experiments, survey design including direct assessment of the key subjective attribute PEF, elicitation of consumer preference, measurement of purported subjective mechanisms (for the PEF case, whether the design is “inspired by nature”), measurement of respondent characteristics (for the PEF case, environmental attitudes and demographics), statistical analysis of data, and validation. Results for the PEF example indicate that silhouettes perceived as environmentally friendly are the most preferred. Design variables that correlated with PEF were identified and used to generate new designs, which were validated in a follow-up study. Implications of using the general methodology in engineering design are discussed. [ABSTRACT FROM AUTHOR]

The transmission error of gears is an important factor for power transmissions, particularly automotive. Consequently, a lot of research has been conducted on the gear transmission. However, in contrast, there remains relatively little research clarifying the characteristics of gear transmission error and its relationship to the tooth flank form. The authors have proposed a general model for tooth meshing between gears. This expresses the transmission error theoretically from a quasi-infinite elastic model, which is composed of springs with stiffness specific to the gears. In this report, the influence of tooth flank form deviation on transmission error is further investigated by using this model. It is shown that the form of the ridge curve of the tooth flank form deviation greatly influences the actual contact ratio at the minimum point of peak-to-peak value of transmission error. The peak-to-peak value of transmission error is affected by the amplitude and the form of the ridge curve. [ABSTRACT FROM AUTHOR]

The proper orthogonal decomposition method has been employed to extract the important field signatures of random field observed in an engineering product or process. Our preliminary study found that the coefficients of the signatures are statistically uncorrelated but may be dependent. To this point, the statistical dependence of the coefficients has been ignored in the random field characterization for probability analysis and design. This paper thus proposes an effective random field characterization method that can account for the statistical dependence among the coefficients for probability analysis and design. The proposed approach has two technical contributions. The first contribution is the development of a natural approximation scheme of random field while preserving prescribed approximation accuracy. The coefficients of the signatures can be modeled as random field variables, and their statistical properties are identified using the chi-square goodness-of-fit test. Then, as the paper’s second technical contribution, the Rosenblatt transformation is employed to transform the statistically dependent random field variables into statistically independent random field variables. The number of the transformation sequences exponentially increases as the number of random field variables becomes large. It was found that improper selection of a transformation sequence among many may introduce high nonlinearity into system responses, which may result in inaccuracy in probability analysis and design. Hence, this paper proposes a novel procedure of determining an optimal sequence of the Rosenblatt transformation that introduces the least degree of nonlinearity into the system response. The proposed random field characterization can be integrated with any advanced probability analysis method, such as the eigenvector dimension reduction method or polynomial chaos expansion method. Three structural examples, including a microelectromechanical system bistable mechanism, are used to demonstrate the effectiveness of the proposed approach. The results show that the statistical dependence in the random field characterization cannot be neglected during probability analysis and design. Moreover, it is shown that the proposed random field approach is very accurate and efficient. [ABSTRACT FROM AUTHOR]

This paper presents a new method in designing the core layer of adaptive sandwich structures. The proposed design formulation treats the core layer as a compliant unit cell network while the unit cell network is synthesized by repeatedly linked identical compliant unit cells. Each unit cell is designed to possess shape adaptive functions independently and through the accumulation of the number of cells within the network, the global adaptive functions are accumulated also. Therefore, the network is capable of achieving large scale shape adaptations of complex profile with high fidelity. Topology optimization is used to design the compliant unit cell. Depending on the problem formulation, topology optimization can perform the simultaneous design of both the host material and the actuation material in the defined environment. This research includes a numerical case study to illustrate the technical aspects of this design philosophy. This is followed by the rapid prototyping of two scaled models and experimental validation. [ABSTRACT FROM AUTHOR]

All areas of engineering have a need to find appropriate aggregated outcomes for systems. Issues range from decision problems, “divide-and-conquer” approaches that include aspects of multidisciplinary design optimization and the effects of a division of labor for, perhaps, a design project, the inefficiencies that can accompany multidisciplinary projects involving, say, design, manufacturing, and sales, to the complexities of multiscale design, analysis, and even nanotechnology. But as shown, if the adopted approach (e.g., management choices, divide-and-conquer methodology, modeling of the biology/physics, decision rule, etc.) satisfies particular accepted practices, then certain complexities and inefficiencies must be anticipated. A disturbing corollary is that even should “success” appear to have been achieved with an approach that satisfies these conditions, it need not be as firm as expected. Ways to improve methodologies must avoid the specified conditions. [ABSTRACT FROM AUTHOR]

Uncertainty in the input parameters to an engineering system may not only degrade the system’s performance but may also cause failure or infeasibility. This paper presents a new sensitivity analysis based approach called design improvement by sensitivity analysis (DISA). DISA analyzes the interval uncertainty of input parameters and using multi-objective optimization, determines an optimal combination of design improvements that will ensure a minimal variation in the objective functions of the system, while also ensuring the feasibility. The approach provides a designer with options for both uncertainty reduction and, more importantly, slight design adjustments. A two-stage sequential framework is used that can employ either the original analysis functions or their metamodels to greatly increase the computational efficiency of the approach. This new approach has been applied to two engineering examples of varying difficulty to demonstrate its applicability and effectiveness. The results produced by these examples show the ability of the approach to ensure the feasibility of a preexisting design under interval uncertainty by effectively adjusting available degrees of freedom in the system without the need to completely redesign the system. [ABSTRACT FROM AUTHOR]

The issue of environmental sustainability, which is unprecedented in both magnitude and complexity, presents one of the biggest challenges faced by modern society. Design engineers can make significant contributions by incorporating environmental awareness into product and process development. It is critical that engineers make a paradigm shift in product design from centering on cost and performance to balancing economic, environmental, and societal considerations. Although there have been quite a few designs for environment (or ecodesign) tools developed, so far, these tools have only achieved limited industrial penetration. The present-day methods are either too qualitative to offer concrete solutions and not effective for designers with limited experience or too quantitative, costly, and time consuming. Thus, current ecodesign tools cannot be implemented during the early design phases. This paper develops a novel, semiquantitative ecodesign methodology that is targeted specifically toward the early stages of the design process. The new methodology is a combination of environmental life cycle assessment and visual tools such as quality function deployment, functional-component matrix, and Pugh chart. Since the early design process is function-oriented, a new visual tool called the function impact matrix has been developed to correlate environmental impacts with product function. Redesign of office staplers for reduced carbon footprint has been selected as a case study to demonstrate the use of the proposed approach. Life cycle assessment results confirm that the new stapler design generated using this methodology promotes improved environmental performance. [ABSTRACT FROM AUTHOR]

This paper describes a study to understand the use of analogies by design engineers with different levels of experience in an adaptive design domain. Protocol analyses of 12 design engineers have been analyzed to understand the functions and reasoning of the analogies. The protocols are real-world data from the aerospace industry. The findings indicate a significant difference in both the use of analogies by novices and experienced designers and the reasoning from the analogies. Novices were found to predominantly transfer information related to the geometric properties without explicit reference to relevant design issues or to the appropriateness of applying the analogy, whereas experienced designers tended to use analogies for problem solving and problem identification. Experienced designers were found to use the analogy to reason about the function of a component and the predicted behavior of the component, whereas the novices seem to lack such reasoning processes. [ABSTRACT FROM AUTHOR]

In real-world applications, a nominal model is usually used to approximate the practical system for design and control. This approximation may make the traditional robust design less effective because the model uncertainty still affects the system performance. In this paper, a novel robust design approach is proposed to improve the system robustness to the variations in design variables as well as the model uncertainty. The proposed robust design consists of two separate optimizations. One is to minimize the variation effects of the design variables to the performance based on the nominal model just as what the traditional deterministic robust design methods do. The other is to minimize the effect of the model uncertainty using the matrix perturbation theory. Through solving a multi-objective optimization problem, the proposed design can improve the system robustness to the uncertainty. Simulation examples have demonstrated the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]

Design recovery is defined as determining the relevant form and functions and their relationships for a component in order to generate a complete engineering representation. To lead to a more complete model, an integrated approach that assesses the component from different perspectives is presented here, as no one perspective or set of tools can provide a comprehensive engineering representation. There is always the potential for error; hence, the necessity to assess latent design and/or design recovery issues in rigorous manner. A modified failure modes and effects analysis (FMEA) was developed to provide a foundation for the reconstructed model’s design validation. The modified FMEA is designed to interface directly with the design recovery framework. A matrix based procedure, which considers feature functions and relationships, is developed to assist the designer to quickly assess the feature design using a consistent structured approach. The results are plotted, and subsequent testing strategies are suggested based on the characteristics of the features being assessed. Examples illustrate the proposed methodologies and highlight their merits. [ABSTRACT FROM AUTHOR]

Cylindrical milling of a screw rotor groove in a single screw compressor has higher machining efficiency than turning. However, the screw groove bottom produced by the flat end of the milling cutter fails to mesh hermetically with the flat tooth tip due to the oversized clearance between them. The clearance forms two leakage paths leading to a compressed gas leakage. The shape of the path is roughly the same as that of two parallel oblate divergent nozzles in an inverse orientation. A mathematical simulation is presented for the surface profile of the screw groove bottom for a single screw compressor generated using several cylindrical milling cutters. The results contribute to improving the design of the meshing pairs in the single screw compressor. [ABSTRACT FROM AUTHOR]

Design project management involves sophisticated task planning that needs to streamline a number of design activities while properly allocating resources associated with these activities. In the field of product family design, there is a lack of comprehensive modeling and analysis formalisms for design project management. In this respect, this paper proposes a modular design project approach to support design project modeling and planning for product families. Design activities are identified as project modules according to the activity sequences, along with the players and resources involved in each activity. A generic variety structure is introduced to characterize the differentiation of design activities among various project variants of the family. Based on the identified modules of activities, design project planning is formulated as a project reconfiguration problem, for which genetic algorithms are employed for configuration evaluation. A case study of truck cab family design in an automobile company demonstrates that design project modularization enhances the coordination of multiple design projects of product families and contributes to the achievement of economy of scale through reusing proven elements. [ABSTRACT FROM AUTHOR]

It has been widely observed that the mass (or weight) and cost of geared transmission systems is a relatively simple function of the maximum continuous torques to be transmitted. This fact may be used to derive simple design tools, which allow rapid comparison of the size and mass of a wide range of designs. Particularly influential is the effect of the configuration: the ratio, number, and disposition of the stages of gearing. In the present paper, a “configuration factor” is developed for the design of multistage, multiple layshaft gearboxes, based on a simplified mass comparison of gearsets designed for the same duty. The results are used to explore the effects of ratio-split, thin-rim designs, and layshaft numbers. [ABSTRACT FROM AUTHOR]

A novel spherical gripper mechanism with one degree of freedom was designed. This gripper consists of a network of spherical parallelogram mechanisms. Design limits, work space formulas, and required grasping forces were derived. Parallelogram mechanisms with unequal circular and spiral linkages were also investigated. It was shown that the spherical parallelogram mechanisms with spiral linkages may be used for grasping objects. [ABSTRACT FROM AUTHOR]

Noncircular bevel gear can achieve variable transmission between intersecting axes. Based on polar coordinates, a design method for noncircular bevel gears is presented. The geometric characteristic of tooth profiles of the gears can be obtained by means of geometry principles for spherical engagement and a pair of conjugated crown racks, which can engage with the driver noncircular bevel gear and driven one, respectively. A series of new conception such as tangent azimuth angle, concavity of conical surfaces, and module angle are proposed to describe spherical geometry relationship in meshing. Meanwhile, geometrical characters of the crown rack cutter are derived. Based on this cutter, the accurate mathematical model of noncircular bevel gear tooth profile is deduced, and the determinant criterion for undercutting is presented. As an example, the three-dimensional models of noncircular bevel gear pair are established to demonstrate the feasibility of the proposed method. A noncircular bevel gear set can be designed by this method if the special included angle for intersecting axes and transmission function ratio are given. [ABSTRACT FROM AUTHOR]