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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]

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 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]

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]

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]

A fast coeff_token decoding method based on new memory architecture is proposed to implement an efficient context-based adaptive variable length-coding (CAVLC) decoder. The heavy memory access needed in CAVLC decoding is a significant issue in designing a real system, such as digital multimedia broadcasting players, portable media players, and mobile phones with video, because it results in high power consumption and delay in operations. Recently, a new coeff_token variable-length decoding method has been suggested to achieve memory access reduction. However, it still requires a large portion of the total memory access in CAVLC decoding. In this work, an effective memory architecture is designed through careful examination of codewords in variable-length code tables. In addition, a novel fast decoding method is proposed to further reduce the memory accesses required for reconstructing the coeff_token element. Only one memory access is used for reconstructing each coeff_token element in the proposed 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]

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]

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]

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]

The article features the Berkely Lower Extremity Exoskeleton, the first functional load-carrying exoskeleton. It can walk at the average speed of 1.3 mls while lifting a 34 kg load. The 4 basic technologies related with the exoskeleton: the architecture design, control schemes, the body local area network, and the series of on-board power units were tackled. An overview of one of the control schemes is also given with the analysis that extends the definition of a system's sensitivity function.

The article presents works to investigate alternative designs for machines for biomimetic locomotion in liquid environments. Two models are proposed to describe the compliant mechanisms' dynamics that can be used to acquire biomimetic locomotion. Analytical solutions for mechanism design were also described.