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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]

A new energy-based life prediction framework for calculation of axial and bending fatigue results at various stress ratios has been developed. The purpose of the life prediction framework is to assess the behavior of materials used in gas turbine engines, such as Titanium 6Al-4V (Ti 6A1-4V) and Aluminum 6061-T6 (Al 6061-T6). The work conducted to develop this energy-based framework consists of the following entities. (1) a new life prediction criterion for axial and bending fatigue at various stress ratios for Al 6061-T6, (2) the use of the previously developed improved uniaxial energy-based method to acquire fatigue life prior to endurance limit region (Scott-Emuakpor et a!., 2007, "Development of an Improved High Cycle Fatigue Criterion," ASME J. Eng. Gas Turbines Power, 129, pp. 162-169), (3) and the incorporation of a probabilistic energy-based fatigue life calculation scheme to the general uniaxial life criterion (the first entity of the frame- work), which is capable of constructing prediction intervals based on a specified percent confidence level. The precision of this work was verified by comparison between theoretical approximations and experimental results from recently acquired Al 606-T6 and Ti 6A1-4V data. The comparison shows very good agreement, thus validating the capability of the framework to produce accurate uniaxial fatigue life predictions for commonly used gas turbine engine materials. [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]